-\input texinfo
+_dnl__ -*-Texinfo-*-
+_dnl__ Copyright (c) 1988 1989 1990 1991 1992 Free Software Foundation, Inc.
+_dnl__ $Id$
+\input texinfo @c -*-texinfo-*-
+@c Copyright (c) 1988 1989 1990 1991 1992 Free Software Foundation, Inc.
+@c %**start of header
@setfilename _GDBP__.info
-@c
-@c NOTE: this manual is marked up for preprocessing with a collection
-@c of m4 macros called "pretex.m4". If you see <_if__> and <_fi__>
-@c scattered around the source, you have the full source before
-@c preprocessing; if you don't, you have the source configured for
-@c _HOST__ architectures (and you can of course get the full source,
-@c with all configurations, from wherever you got this).
+_if__(_GENERIC__)
+@settitle _GDBN__, The GNU Debugger
+_fi__(_GENERIC__)
+_if__(!_GENERIC__)
+@settitle _GDB__, The GNU Debugger (_HOST__)
+_fi__(!_GENERIC__)
+@setchapternewpage odd
+@c @smallbook
+@c @cropmarks
+@c %**end of header
+
+@finalout
+@syncodeindex ky cp
+
+_0__@c ===> NOTE! <==_1__
+@c Determine the edition number in *three* places by hand:
+@c 1. First ifinfo section 2. title page 3. top node
+@c To find the locations, search for !!set
+
+@c The following is for Pesch for his RCS system.
+@c This revision number *not* the same as the Edition number.
+@tex
+\def\$#1${{#1}} % Kluge: collect RCS revision info without $...$
+\xdef\manvers{\$Revision$} % For use in headers, footers too
+@end tex
+
+@c GDB CHANGELOG CONSULTED BETWEEN:
+@c Fri Oct 11 23:27:06 1991 John Gilmore (gnu at cygnus.com)
+@c Sat Dec 22 02:51:40 1990 John Gilmore (gnu at cygint)
+
+@c THIS MANUAL REQUIRES TEXINFO-2 macros and info-makers to format properly.
+
+@ifinfo
+@format
+START-INFO-DIR-ENTRY
+* Gdb: (gdb). The GNU debugger.
+END-INFO-DIR-ENTRY
+@end format
+@end ifinfo
_if__(0)
-THIS IS THE FULL SOURCE. The full source needs to be run through m4
-before either tex- or info- formatting: for example,
- m4 pretex.m4 none.m4 m680x0.m4 as.texinfo >as-680x0.texinfo
-will produce (assuming your path finds either GNU or SysV m4; Berkeley
-won't do) a file suitable for formatting. See the text in "pretex.m4"
-for a fuller explanation (and the macro definitions).
+NOTE: this manual is marked up for preprocessing with a collection
+of m4 macros called "pretex.m4".
+
+THIS IS THE SOURCE PRIOR TO PREPROCESSING. The full source needs to
+be run through m4 before either tex- or info- formatting: for example,
+_0__
+ m4 pretex.m4 none.m4 all.m4 gdb.texinfo >gdb-all.texinfo
+will produce (assuming your path finds either GNU m4 >= 0.84, or SysV
+m4; Berkeley will not do) a file suitable for formatting. See the text in
+"pretex.m4" for a fuller explanation (and the macro definitions).
+_1__
_fi__(0)
@c
-@synindex ky cp
-@c FOR UPDATES LEADING TO THIS DRAFT, GDB CHANGELOG CONSULTED BETWEEN:
-@c Tue Feb 26 01:47:07 1991 Cygnus John Gilmore (cygnus at yuba)
-@c Sat Dec 22 02:51:40 1990 John Gilmore (gnu at cygint)
@ifinfo
This file documents the GNU debugger _GDBN__.
-Copyright (C) 1988, 1989, 1990, 1991 Free Software Foundation, Inc.
+@c !!set edition, date, version
+This is Edition 4.05, June 1992,
+of @cite{Using GDB: A Guide to the GNU Source-Level Debugger}
+for GDB Version _GDB_VN__.
+
+Copyright (C) 1988, 1989, 1990, 1991, 1992 Free Software Foundation, Inc.
Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
are preserved on all copies.
@ignore
-Permission is granted to process this file through Tex and print the
+Permission is granted to process this file through TeX and print the
results, provided the printed document carries copying permission
notice identical to this one except for the removal of this paragraph
(this paragraph not being relevant to the printed manual).
Permission is granted to copy and distribute translations of this manual
into another language, under the above conditions for modified versions,
except that the section entitled ``GNU General Public License'' may be
-included in a translation approved by the author instead of in the
-original English.
+included in a translation approved by the Free Software Foundation
+instead of in the original English.
@end ifinfo
-@smallbook
-@setchapternewpage odd
-_if__(_GENERIC__)
-@settitle Using _GDBN__ (v4.0)
-_fi__(_GENERIC__)
-_if__(!_GENERIC__)
-@settitle Using _GDBN__ v4.0 (_HOST__)
-_fi__(!_GENERIC__)
-@iftex
-@c @finalout
-@end iftex
+
@titlepage
-@title{Using _GDBN__}
-@subtitle{A Guide to the GNU Source-Level Debugger}
+@title Using _GDBN__
+@subtitle The GNU Source-Level Debugger
_if__(!_GENERIC__)
-@subtitle{On _HOST__ Systems}
+@subtitle on _HOST__ Systems
_fi__(!_GENERIC__)
@sp 1
-@c Maybe crank this up to "Fourth Edition" when released at FSF
-@c @subtitle Third Edition---_GDBN__ version 4.0
-@subtitle _GDBN__ version 4.0
-@subtitle January 1991
-@author{Richard M. Stallman}
-@author{Roland H. Pesch (Cygnus Support)}
+@c !!set edition, date, version
+@subtitle Edition 4.05, for _GDBN__ version _GDB_VN__
+@subtitle June 1992
+@author by Richard M. Stallman and Roland H. Pesch
@page
-
@tex
-\def\$#1${{#1}} % Kluge: collect RCS revision info without $...$
-\xdef\manvers{\$Revision$} % For use in headers, footers too
{\parskip=0pt
-\hfill Cygnus Support\par
-\hfill \manvers\par
+\hfill pesch\@cygnus.com\par
+\hfill {\it Using _GDBN__}, \manvers\par
\hfill \TeX{}info \texinfoversion\par
}
@end tex
@vskip 0pt plus 1filll
-Copyright @copyright{} 1988, 1989, 1990, 1991 Free Software Foundation, Inc.
+Copyright @copyright{} 1988, 1989, 1990, 1991, 1992 Free Software Foundation, Inc.
Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
Permission is granted to copy and distribute translations of this manual
into another language, under the above conditions for modified versions,
except that the section entitled ``GNU General Public License'' may be
-included in a translation approved by the author instead of in the
-original English.
+included in a translation approved by the Free Software Foundation
+instead of in the original English.
@end titlepage
@page
-@node Top, New Features, (dir), (dir)
+@ifinfo
+@node Top, Summary, (dir), (dir)
+@top _GDBN__, the GNU symbolic debugger
+
+This file describes _GDBN__, the GNU symbolic debugger.
+
+@c !!set edition, date, version
+This is Edition 4.05, June 1992, for GDB Version _GDB_VN__.
+@end ifinfo
+
+@menu
+* Summary:: Summary of _GDBN__
+* New Features:: New features since GDB version 3.5
+* Sample Session:: A sample _GDBN__ session
+* Invocation:: Getting in and out of _GDBN__
+* Commands:: _GDBN__ commands
+* Running:: Running programs under _GDBN__
+* Stopping:: Stopping and continuing
+* Stack:: Examining the stack
+* Source:: Examining source files
+* Data:: Examining data
+* Languages:: Using _GDBN__ with different languages
+* Symbols:: Examining the symbol table
+* Altering:: Altering execution
+* _GDBN__ Files:: _GDBN__'s files
+* Targets:: Specifying a debugging target
+* Controlling _GDBN__:: Controlling _GDBN__
+* Sequences:: Canned sequences of commands
+* Emacs:: Using _GDBN__ under GNU Emacs
+* _GDBN__ Bugs:: Reporting bugs in _GDBN__
+* Renamed Commands::
+* Formatting Documentation:: How to format and print GDB documentation
+* Installing GDB:: Installing GDB
+* Copying:: GNU GENERAL PUBLIC LICENSE
+* Index:: Index
+
+ --- The Detailed Node Listing ---
+
+Summary of _GDBN__
+
+* Free Software:: Freely redistributable software
+* Contributors:: Contributors to _GDBN__
+
+Getting In and Out of _GDBN__
+
+* Invoking _GDBN__:: How to start _GDBN__
+* Leaving _GDBN__:: How to quit _GDBN__
+* Shell Commands:: How to use shell commands inside _GDBN__
+
+Starting _GDBN__
+
+* File Options:: Choosing Files
+* Mode Options:: Choosing Modes
+
+_GDBN__ Commands
+
+* Command Syntax:: Command Syntax
+* Completion:: Command Completion
+* Help:: Getting Help
+
+Running Programs Under _GDBN__
+
+* Compilation:: Compiling for Debugging
+* Starting:: Starting your Program
+* Arguments:: Your Program's Arguments
+* Environment:: Your Program's Environment
+* Working Directory:: Your Program's Working Directory
+* Input/Output:: Your Program's Input and Output
+* Attach:: Debugging an Already-Running Process
+* Kill Process:: Killing the Child Process
+* Process Information:: Additional Process Information
+
+Stopping and Continuing
+
+* Breakpoints:: Breakpoints, Watchpoints, and Exceptions
+* Continuing and Stepping:: Resuming Execution
+* Signals:: Signals
+
+Breakpoints, Watchpoints, and Exceptions
+
+* Set Breaks:: Setting Breakpoints
+* Set Watchpoints:: Setting Watchpoints
+* Exception Handling:: Breakpoints and Exceptions
+* Delete Breaks:: Deleting Breakpoints
+* Disabling:: Disabling Breakpoints
+* Conditions:: Break Conditions
+* Break Commands:: Breakpoint Command Lists
+* Breakpoint Menus:: Breakpoint Menus
+* Error in Breakpoints:: ``Cannot insert breakpoints''
+
+Examining the Stack
+
+* Frames:: Stack Frames
+* Backtrace:: Backtraces
+* Selection:: Selecting a Frame
+* Frame Info:: Information on a Frame
+
+Examining Source Files
+
+* List:: Printing Source Lines
+* Search:: Searching Source Files
+* Source Path:: Specifying Source Directories
+* Machine Code:: Source and Machine Code
+
+Examining Data
+
+* Expressions:: Expressions
+* Variables:: Program Variables
+* Arrays:: Artificial Arrays
+* Output formats:: Output formats
+* Memory:: Examining Memory
+* Auto Display:: Automatic Display
+* Print Settings:: Print Settings
+* Value History:: Value History
+* Convenience Vars:: Convenience Variables
+* Registers:: Registers
+* Floating Point Hardware:: Floating Point Hardware
+
+Using GDB with Different Languages
+
+* Setting:: Switching between source languages
+* Show:: Displaying the language
+* Checks:: Type and Range checks
+* Support:: Supported languages
+
+Switching between source languages
+
+* Manually:: Setting the working language manually
+* Automatically:: Having GDB infer the source language
+
+Type and range Checking
+
+* Type Checking:: An overview of type checking
+* Range Checking:: An overview of range checking
+
+Supported Languages
+
+* C:: C and C++
+* Modula-2:: Modula-2
+
+C and C++
+
+* C Operators:: C and C++ Operators
+* C Constants:: C and C++ Constants
+* Cplusplus expressions:: C++ Expressions
+* C Defaults:: Default settings for C and C++
+* C Checks:: C and C++ Type and Range Checks
+* Debugging C:: _GDBN__ and C
+* Debugging C plus plus:: Special features for C++
+
+Modula-2
+
+* M2 Operators:: Built-in operators
+* Built-In Func/Proc:: Built-in Functions and Procedures
+* M2 Constants:: Modula-2 Constants
+* M2 Defaults:: Default settings for Modula-2
+* Deviations:: Deviations from standard Modula-2
+* M2 Checks:: Modula-2 Type and Range Checks
+* M2 Scope:: The scope operators @code{::} and @code{.}
+* GDB/M2:: GDB and Modula-2
+
+Altering Execution
+
+* Assignment:: Assignment to Variables
+* Jumping:: Continuing at a Different Address
+* Signaling:: Giving your program a Signal
+* Returning:: Returning from a Function
+* Calling:: Calling your Program's Functions
+* Patching:: Patching your Program
+
+_GDBN__'s Files
+
+* Files:: Commands to Specify Files
+* Symbol Errors:: Errors Reading Symbol Files
+
+Specifying a Debugging Target
+
+* Active Targets:: Active Targets
+* Target Commands:: Commands for Managing Targets
+* Remote:: Remote Debugging
+
+Remote Debugging
+
+* i960-Nindy Remote:: _GDBN__ with a Remote i960 (Nindy)
+* EB29K Remote:: _GDBN__ with a Remote EB29K
+* VxWorks Remote:: _GDBN__ and VxWorks
+
+_GDBN__ with a Remote i960 (Nindy)
+
+* Nindy Startup:: Startup with Nindy
+* Nindy Options:: Options for Nindy
+* Nindy reset:: Nindy Reset Command
+
+_GDBN__ with a Remote EB29K
+
+* Comms (EB29K):: Communications Setup
+* gdb-EB29K:: EB29K cross-debugging
+* Remote Log:: Remote Log
+
+_GDBN__ and VxWorks
+
+* VxWorks connection:: Connecting to VxWorks
+* VxWorks download:: VxWorks Download
+* VxWorks attach:: Running Tasks
+
+Controlling _GDBN__
+
+* Prompt:: Prompt
+* Editing:: Command Editing
+* History:: Command History
+* Screen Size:: Screen Size
+* Numbers:: Numbers
+* Messages/Warnings:: Optional Warnings and Messages
+
+Canned Sequences of Commands
+
+* Define:: User-Defined Commands
+* Command Files:: Command Files
+* Output:: Commands for Controlled Output
+
+Reporting Bugs in _GDBN__
+
+* Bug Criteria:: Have You Found a Bug?
+* Bug Reporting:: How to Report Bugs
+
+Installing GDB
+
+* Separate Objdir:: Compiling _GDBN__ in another directory
+* Config Names:: Specifying names for hosts and targets
+* configure Options:: Summary of options for configure
+@end menu
+
+@node Summary, New Features, Top, Top
@unnumbered Summary of _GDBN__
The purpose of a debugger such as _GDBN__ is to allow you to see what is
going on ``inside'' another program while it executes---or what another
-program was doing at the moment it crashed.
+program was doing at the moment it crashed.
_GDBN__ can do four main kinds of things (plus other things in support of
these) to help you catch bugs in the act:
-@enumerate
+@itemize @bullet
@item
Start your program, specifying anything that might affect its behavior.
@item
Change things in your program, so you can experiment with correcting the
effects of one bug and go on to learn about another.
-@end enumerate
+@end itemize
-_GDBN__ can be used to debug programs written in C and C++. Pascal support
-is being implemented, and Fortran support will be added when a GNU
-Fortran compiler is ready.
+You can use _GDBN__ to debug programs written in C, C++, and Modula-2.
+Fortran support will be added when a GNU Fortran compiler is ready.
-@node Free Software,,,
+@menu
+* Free Software:: Free Software
+* Contributors:: Contributors to GDB
+@end menu
+
+@node Free Software, Contributors, Summary, Summary
@unnumberedsec Free Software
-_GDBN__ is Free Software, protected by the GNU General Public License (GPL).
-The GPL gives you the freedom to copy or adapt a licensed
+
+_GDBN__ is @dfn{free software}, protected by the GNU General Public License
+(GPL). The GPL gives you the freedom to copy or adapt a licensed
program---but every person getting a copy also gets with it the
freedom to modify that copy (which means that they must get access to
the source code), and the freedom to distribute further copies.
Free Software Foundation uses the GPL to preserve these freedoms.
Fundamentally, the General Public License is a license which says that
-you have these freedoms and that you can't take these freedoms away
+you have these freedoms and that you cannot take these freedoms away
from anyone else.
-For full details, @pxref{License}.
+For full details, @pxref{Copying, ,GNU GENERAL PUBLIC LICENSE}.
-@node New Features, Invocation, Top, Top
-@unnumbered New Features in _GDBN__ version 4.0
+@node Contributors, , Free Software, Summary
+@unnumberedsec Contributors to GDB
-@itemize @bullet
-@item
-TARGETS: Using the new command @samp{target}, you can select at runtime
-whether you are debugging local files, local processes, standalone
-systems over the serial port, realtime systems over a TCP/IP
-connection, etc. _GDBN__ now uses a function vector to mediate access to
-all the different possible targets, making it much easier to add
-support for new remote protocols.
+Richard Stallman was the original author of GDB, and of many other GNU
+programs. Many others have contributed to its development. This
+section attempts to credit major contributors. One of the virtues of
+free software is that everyone is free to contribute to it; with
+regret, we cannot actually acknowledge everyone here. The file
+@file{ChangeLog} in the GDB distribution approximates a blow-by-blow
+account.
-@item
-WATCHPOINTS: _GDBN__ now sports watchpoints as well as breakpoints. You can
-use a watchpoint to stop execution whenever the value of an expression
-changes, without having to predict a particular place in the inferior
-process where this may happen.
+Changes much prior to version 2.0 are lost in the mists of time.
-@item
-OBJECT CODE FORMATS: _GDBN__ uses a new scheme called Binary File
-Descriptors (BFD) to permit it to switch dynamically, without
-reconfiguration or recompilation, between different object-file
-formats. Formats currently supported are COFF, a.out, and the new
-Intel 960 b.out; files may be read as .o's, archive libraries, or core
-dumps. BFD is available as a subroutine library so that other
-programs may take advantage of it, and the other GNU binary utilities
-are being converted to use it.
+@quotation
+@emph{Plea:} Additions to this section are particularly welcome. If you
+or your friends (or enemies; let's be evenhanded) have been unfairly
+omitted from this list, we would like to add your names!
+@end quotation
-@item
-CONFIGURATION: You must still choose a particular machine architecture
-and operating system for _GDBN__'s host and target systems when _GDBN__ is built.
-The script @samp{config.gdb} now handles specification of separate host
-and target configurations.
+So that they may not regard their long labor as thankless, we
+particularly thank those who shepherded GDB through major releases: Stu
+Grossman and John Gilmore (releases 4.6, 4.5, 4.4), John Gilmore
+(releases 4.3, 4.2, 4.1, 4.0, and 3.9); Jim Kingdon (releases 3.5, 3.4,
+3.3); and Randy Smith (releases 3.2, 3.1, 3.0). As major maintainer of
+GDB for some period, each contributed significantly to the structure,
+stability, and capabilities of the entire debugger.
+
+Richard Stallman, assisted at various times by Pete TerMaat, Chris
+Hanson, and Richard Mlynarik, handled releases through 2.8.
+
+Michael Tiemann is the author of most of the GNU C++ support in GDB,
+with significant additional contributions from Per Bothner. James
+Clark wrote the GNU C++ demangler. Early work on C++ was by Peter
+TerMaat (who also did much general update work leading to release 3.0).
+
+GDB 4 uses the BFD subroutine library to examine multiple
+object-file formats; BFD was a joint project of David V.
+Henkel-Wallace, Rich Pixley, Steve Chamberlain, and John Gilmore.
+
+David Johnson wrote the original COFF support; Pace Willison did
+the original support for encapsulated COFF.
+
+Adam de Boor and Bradley Davis contributed the ISI Optimum V support.
+Per Bothner, Noboyuki Hikichi, and Alessandro Forin contributed MIPS
+support. Jean-Daniel Fekete contributed Sun 386i support. Chris
+Hanson improved the HP9000 support. Noboyuki Hikichi and Tomoyuki
+Hasei contributed Sony/News OS 3 support. David Johnson contributed
+Encore Umax support. Jyrki Kuoppala contributed Altos 3068 support.
+Keith Packard contributed NS32K support. Doug Rabson contributed
+Acorn Risc Machine support. Chris Smith contributed Convex support
+(and Fortran debugging). Jonathan Stone contributed Pyramid support.
+Michael Tiemann contributed SPARC support. Tim Tucker contributed
+support for the Gould NP1 and Gould Powernode. Pace Willison
+contributed Intel 386 support. Jay Vosburgh contributed Symmetry
+support.
+
+Rich Schaefer and Peter Schauer helped with support of SunOS shared
+libraries.
+
+Jay Fenlason and Roland McGrath ensured that GDB and GAS agree about
+several machine instruction sets.
+
+Patrick Duval, Ted Goldstein, Vikram Koka and Glenn Engel helped
+develop remote debugging. Intel Corporation and Wind River Systems
+contributed remote debugging modules for their products.
+
+Brian Fox is the author of the readline libraries providing
+command-line editing and command history.
+
+Andrew Beers of SUNY Buffalo wrote the language-switching code and
+the Modula-2 support, and contributed the Languages chapter of this
+manual.
+
+Fred Fish wrote most of the support for Unix System Vr4, and enhanced
+the command-completion support to cover C++ overloaded symbols.
+
+@node New Features, Sample Session, Summary, Top
+@unnumbered New Features since GDB version 3.5
+
+@table @emph
+@item Targets
+Using the new command @code{target}, you can select at runtime whether
+you are debugging local files, local processes, standalone systems over
+a serial port, realtime systems over a TCP/IP connection, etc. The
+command @code{load} can download programs into a remote system. Serial
+stubs are available for Motorola 680x0 and Intel 80386 remote systems;
+GDB also supports debugging realtime processes running under
+VxWorks, using SunRPC Remote Procedure Calls over TCP/IP to talk to a
+debugger stub on the target system. Internally, GDB now uses a
+function vector to mediate access to different targets; if you need to
+add your own support for a remote protocol, this makes it much easier.
+
+@item Watchpoints
+GDB now sports watchpoints as well as breakpoints. You can use a
+watchpoint to stop execution whenever the value of an expression
+changes, without having to predict a particular place in your program
+where this may happen.
+
+@item Wide Output
+Commands that issue wide output now insert newlines at places designed
+to make the output more readable.
+
+@item Object Code Formats
+GDB uses a new library called the Binary File Descriptor (BFD)
+Library to permit it to switch dynamically, without reconfiguration or
+recompilation, between different object-file formats. Formats currently
+supported are COFF, a.out, and the Intel 960 b.out; files may be read as
+.o's, archive libraries, or core dumps. BFD is available as a
+subroutine library so that other programs may take advantage of it, and
+the other GNU binary utilities are being converted to use it.
+
+@item Configuration and Ports
+Compile-time configuration (to select a particular architecture and
+operating system) is much easier. The script @code{configure} now
+allows you to configure GDB as either a native debugger or a
+cross-debugger. @xref{Installing GDB}, for details on how to
+configure.
+
+@item Interaction
+The user interface to GDB's control variables has been simplified
+and consolidated in two commands, @code{set} and @code{show}. Output
+lines are now broken at readable places, rather than overflowing onto
+the next line. You can suppress output of machine-level addresses,
+displaying only source language information.
-@item
-INTERACTION: _GDBN__ now uses the GNU @code{readline} interface to read its
-input; this provides inline editing of commands, using the familiar
-Emacs or @code{vi} keymaps, and command-history support. The user interface
-to _GDBN__'s control variables has been simplified and consolidated in two
-commands, @samp{set} and @samp{show}. Output lines are now broken at
-readable places, rather than overflowing onto the next line.
+@item C++
+GDB now supports C++ multiple inheritance (if used with a GCC
+version 2 compiler), and also has limited support for C++ exception
+handling, with the commands @code{catch} and @code{info catch}: GDB
+can break when an exception is raised, before the stack is peeled back
+to the exception handler's context.
+
+@item Modula-2
+GDB now has preliminary support for the GNU Modula-2 compiler,
+currently under development at the State University of New York at
+Buffalo. Coordinated development of both GDB and the GNU Modula-2
+compiler will continue into 1992. Other Modula-2 compilers are
+currently not supported, and attempting to debug programs compiled with
+them will likely result in an error as the symbol table of the
+executable is read in.
+
+@item Command Rationalization
+Many GDB commands have been renamed to make them easier to remember
+and use. In particular, the subcommands of @code{info} and
+@code{show}/@code{set} are grouped to make the former refer to the state
+of your program, and the latter refer to the state of GDB itself.
+@xref{Renamed Commands}, for details on what commands were renamed.
+
+@item Shared Libraries
+GDB 4 can debug programs and core files that use SunOS, SVR4, or IBM RS/6000
+shared libraries.
+
+@item Reference Card
+GDB 4 has a reference card. @xref{Formatting Documentation,,Formatting
+the Documentation}, for instructions to print it.
+
+@item Work in Progress
+Kernel debugging for BSD and Mach systems; Tahoe and HPPA architecture
+support.
+@end table
-@item
-SOURCE LANGUAGE: _GDBN__ now understands C++ source as well as C. Multiple
-inheritance is supported when used with G++ 2.0. There is also limited
-support for C++ exception handling: _GDBN__ can break when an exception is
-raised, before the stack is peeled back to the exception handler's
-context. You can suppress output of machine-level addresses,
-displaying only source language information.
+@node Sample Session, Invocation, New Features, Top
+@chapter A Sample _GDBN__ Session
-@item
-PORTS: _GDBN__ has been ported to the following new architectures:
-AT&T 3b1, Acorn RISC machine, HP300 running HPUX, big- and little-
-endian MIPS machines, Motorola 88k, Sun 386i, and Sun 3 running SunOS
-4. In addition, the following are supported as targets only: AMD
-29k, Intel 960, and Wind River's VxWorks.
+You can use this manual at your leisure to read all about _GDBN__.
+However, a handful of commands are enough to get started using the
+debugger. This chapter illustrates these commands.
-@item
-SHARED LIBRARIES: _GDBN__ 4.0 supports SunOS shared libraries.
+@iftex
+In this sample session, we emphasize user input like this: @b{input},
+to make it easier to pick out from the surrounding output.
+@end iftex
-@item
-WORK IN PROGRESS: kernel debugging for BSD and Mach systems; Tahoe and
-HPPA architecture support.
+@c FIXME: this example may not be appropriate for some configs, where
+@c FIXME...primary interest is in remote use.
+_0__
+One of the preliminary versions of GNU @code{m4} (a generic macro
+processor) exhibits the following bug: sometimes, when we change its
+quote strings from the default, the commands used to capture one macro's
+definition in another stop working. In the following short @code{m4}
+session, we define a macro @code{foo} which expands to @code{0000}; we
+then use the @code{m4} built-in @code{defn} to define @code{bar} as the
+same thing. However, when we change the open quote string to
+@code{<QUOTE>} and the close quote string to @code{<UNQUOTE>}, the same
+procedure fails to define a new synonym @code{baz}:
-@end itemize
+@smallexample
+$ @b{cd gnu/m4}
+$ @b{./m4}
+@b{define(foo,0000)}
+
+@b{foo}
+0000
+@b{define(bar,defn(`foo'))}
+
+@b{bar}
+0000
+@b{changequote(<QUOTE>,<UNQUOTE>)}
+
+@b{define(baz,defn(<QUOTE>foo<UNQUOTE>))}
+@b{baz}
+@b{C-d}
+m4: End of input: 0: fatal error: EOF in string
+@end smallexample
+
+@noindent
+Let's use _GDBN__ to try to see what's going on.
+
+@smallexample
+$ @b{_GDBP__ m4}
+@c FIXME: this falsifies the exact text played out, to permit smallbook
+@c FIXME... format to come out better.
+GDB is free software and you are welcome to distribute copies
+ of it under certain conditions; type "show copying" to see
+ the conditions.
+There is absolutely no warranty for GDB; type "show warranty"
+for details.
+GDB _GDB_VN__, Copyright 1992 Free Software Foundation, Inc...
+(_GDBP__)
+@end smallexample
+
+@noindent
+_GDBN__ reads only enough symbol data to know where to find the rest when
+needed; as a result, the first prompt comes up very quickly. We now
+tell _GDBN__ to use a narrower display width than usual, so that examples
+will fit in this manual.
+
+@smallexample
+(_GDBP__) @b{set width 70}
+@end smallexample
+
+@noindent
+Let's see how the @code{m4} built-in @code{changequote} works.
+Having looked at the source, we know the relevant subroutine is
+@code{m4_changequote}, so we set a breakpoint there with _GDBN__'s
+@code{break} command.
+
+@smallexample
+(_GDBP__) @b{break m4_changequote}
+Breakpoint 1 at 0x62f4: file builtin.c, line 879.
+@end smallexample
+
+@noindent
+Using the @code{run} command, we start @code{m4} running under _GDBN__
+control; as long as control does not reach the @code{m4_changequote}
+subroutine, the program runs as usual:
+
+@smallexample
+(_GDBP__) @b{run}
+Starting program: /work/Editorial/gdb/gnu/m4/m4
+@b{define(foo,0000)}
+
+@b{foo}
+0000
+@end smallexample
+
+@noindent
+To trigger the breakpoint, we call @code{changequote}. _GDBN__
+suspends execution of @code{m4}, displaying information about the
+context where it stops.
+
+@smallexample
+@b{changequote(<QUOTE>,<UNQUOTE>)}
+
+Breakpoint 1, m4_changequote (argc=3, argv=0x33c70)
+ at builtin.c:879
+879 if (bad_argc(TOKEN_DATA_TEXT(argv[0]),argc,1,3))
+@end smallexample
+
+@noindent
+Now we use the command @code{n} (@code{next}) to advance execution to
+the next line of the current function.
+
+@smallexample
+(_GDBP__) @b{n}
+882 set_quotes((argc >= 2) ? TOKEN_DATA_TEXT(argv[1])\
+ : nil,
+@end smallexample
+
+@noindent
+@code{set_quotes} looks like a promising subroutine. We can go into it
+by using the command @code{s} (@code{step}) instead of @code{next}.
+@code{step} goes to the next line to be executed in @emph{any}
+subroutine, so it steps into @code{set_quotes}.
+
+@smallexample
+(_GDBP__) @b{s}
+set_quotes (lq=0x34c78 "<QUOTE>", rq=0x34c88 "<UNQUOTE>")
+ at input.c:530
+530 if (lquote != def_lquote)
+@end smallexample
+
+@noindent
+The display that shows the subroutine where @code{m4} is now
+suspended (and its arguments) is called a stack frame display. It
+shows a summary of the stack. We can use the @code{backtrace}
+command (which can also be spelled @code{bt}), to see where we are
+in the stack as a whole: the @code{backtrace} command displays a
+stack frame for each active subroutine.
+
+@smallexample
+(_GDBP__) @b{bt}
+#0 set_quotes (lq=0x34c78 "<QUOTE>", rq=0x34c88 "<UNQUOTE>")
+ at input.c:530
+#1 0x6344 in m4_changequote (argc=3, argv=0x33c70)
+ at builtin.c:882
+#2 0x8174 in expand_macro (sym=0x33320) at macro.c:242
+#3 0x7a88 in expand_token (obs=0x0, t=209696, td=0xf7fffa30)
+ at macro.c:71
+#4 0x79dc in expand_input () at macro.c:40
+#5 0x2930 in main (argc=0, argv=0xf7fffb20) at m4.c:195
+@end smallexample
+
+@noindent
+Let's step through a few more lines to see what happens. The first two
+times, we can use @samp{s}; the next two times we use @code{n} to avoid
+falling into the @code{xstrdup} subroutine.
+
+@smallexample
+(_GDBP__) @b{s}
+0x3b5c 532 if (rquote != def_rquote)
+(_GDBP__) @b{s}
+0x3b80 535 lquote = (lq == nil || *lq == '\0') ? \
+def_lquote : xstrdup(lq);
+(_GDBP__) @b{n}
+536 rquote = (rq == nil || *rq == '\0') ? def_rquote\
+ : xstrdup(rq);
+(_GDBP__) @b{n}
+538 len_lquote = strlen(rquote);
+@end smallexample
+
+@noindent
+The last line displayed looks a little odd; let's examine the variables
+@code{lquote} and @code{rquote} to see if they are in fact the new left
+and right quotes we specified. We can use the command @code{p}
+(@code{print}) to see their values.
+
+@smallexample
+(_GDBP__) @b{p lquote}
+$1 = 0x35d40 "<QUOTE>"
+(_GDBP__) @b{p rquote}
+$2 = 0x35d50 "<UNQUOTE>"
+@end smallexample
+
+@noindent
+@code{lquote} and @code{rquote} are indeed the new left and right quotes.
+Let's look at some context; we can display ten lines of source
+surrounding the current line, with the @code{l} (@code{list}) command.
+
+@smallexample
+(_GDBP__) @b{l}
+533 xfree(rquote);
+534
+535 lquote = (lq == nil || *lq == '\0') ? def_lquote\
+ : xstrdup (lq);
+536 rquote = (rq == nil || *rq == '\0') ? def_rquote\
+ : xstrdup (rq);
+537
+538 len_lquote = strlen(rquote);
+539 len_rquote = strlen(lquote);
+540 @}
+541
+542 void
+@end smallexample
+
+@noindent
+Let's step past the two lines that set @code{len_lquote} and
+@code{len_rquote}, and then examine the values of those variables.
+
+@smallexample
+(_GDBP__) @b{n}
+539 len_rquote = strlen(lquote);
+(_GDBP__) @b{n}
+540 @}
+(_GDBP__) @b{p len_lquote}
+$3 = 9
+(_GDBP__) @b{p len_rquote}
+$4 = 7
+@end smallexample
+
+@noindent
+That certainly looks wrong, assuming @code{len_lquote} and
+@code{len_rquote} are meant to be the lengths of @code{lquote} and
+@code{rquote} respectively. Let's try setting them to better values.
+We can use the @code{p} command for this, since it'll print the value of
+any expression---and that expression can include subroutine calls and
+assignments.
+
+@smallexample
+(_GDBP__) @b{p len_lquote=strlen(lquote)}
+$5 = 7
+(_GDBP__) @b{p len_rquote=strlen(rquote)}
+$6 = 9
+@end smallexample
+
+@noindent
+Let's see if that fixes the problem of using the new quotes with the
+@code{m4} built-in @code{defn}. We can allow @code{m4} to continue
+executing with the @code{c} (@code{continue}) command, and then try the
+example that caused trouble initially:
+
+@smallexample
+(_GDBP__) @b{c}
+Continuing.
+
+@b{define(baz,defn(<QUOTE>foo<UNQUOTE>))}
+
+baz
+0000
+@end smallexample
+
+@noindent
+Success! The new quotes now work just as well as the default ones. The
+problem seems to have been just the two typos defining the wrong
+lengths. We'll let @code{m4} exit by giving it an EOF as input.
+
+@smallexample
+@b{C-d}
+Program exited normally.
+@end smallexample
+
+@noindent
+The message @samp{Program exited normally.} is from _GDBN__; it
+indicates @code{m4} has finished executing. We can end our _GDBN__
+session with the _GDBN__ @code{quit} command.
+
+@smallexample
+(_GDBP__) @b{quit}
+_1__@end smallexample
+
+@node Invocation, Commands, Sample Session, Top
+@chapter Getting In and Out of _GDBN__
+
+This chapter discusses how to start _GDBN__, and how to get out of it.
+(The essentials: type @samp{_GDBP__} to start GDB, and type @kbd{quit}
+or @kbd{C-d} to exit.)
+
+@menu
+* Invoking _GDBN__:: Starting _GDBN__
+* Leaving _GDBN__:: Leaving _GDBN__
+* Shell Commands:: Shell Commands
+@end menu
+
+@node Invoking _GDBN__, Leaving _GDBN__, Invocation, Invocation
+@section Starting _GDBN__
+
+Start _GDBN__ with the shell command @code{_GDBP__}. Once it's running,
+_GDBN__ reads commands from the terminal until you tell it to exit.
+
+You can also run @code{_GDBP__} with a variety of arguments and options,
+to specify more of your debugging environment at the outset.
+
+The command-line options described here are designed
+to cover a variety of situations; in some environments, some of these
+options may effectively be unavailable.
+
+_if__(_H8__)
+For details on starting up _GDBP__ as a
+remote debugger attached to a Hitachi H8/300 board, see @ref{Hitachi
+H8/300 Remote,,_GDBN__ and the Hitachi H8/300}.
+_fi__(_H8__)
+
+The most usual way to start _GDBN__ is with one argument or two,
+specifying an executable program as the argument:
+
+@example
+_GDBP__ @var{program}
+@end example
+
+@noindent
+You can also start with both an executable program and a core file
+specified:
-@node Invocation, User Interface, New Features, Top
-@chapter Starting _GDBN__
+@example
+_GDBP__ @var{program} @var{core}
+@end example
-_GDBN__ is invoked with the shell command @samp{_GDBP__}. Once started, it reads
-commands from the terminal until you tell it to exit.
+You can, instead, specify a process ID as a second argument, if you want
+to debug a running process:
-The most usual way to start _GDBN__ is with one argument or two, specifying
-an executable program as the argument:
@example
-_GDBP__ program
+_GDBP__ @var{program} 1234
@end example
+
+@noindent
+would attach _GDBN__ to process @code{1234} (unless you also have a file
+named @file{1234}; _GDBN__ does check for a core file first).
+
+Taking advantage of the second command-line argument requires a fairly
+complete operating system; when you use _GDBN__ as a remote debugger
+attached to a bare board, there may not be any notion of ``process'',
+and there is often no way to get a core dump.
+
+@noindent
+You can further control how _GDBN__ starts up by using command-line
+options. _GDBN__ itself can remind you of the options available.
+
@noindent
-or you can start with both an executable program and a core file specified:
+Type
+
@example
-_GDBP__ program core
+_GDBP__ -help
@end example
-You can get more detailed control over how _GDBN__ starts up using some of
-the command-line options.
+@noindent
+to display all available options and briefly describe their use
+(@samp{_GDBP__ -h} is a shorter equivalent).
-All the options and command line arguments given are processed
+All options and command line arguments you give are processed
in sequential order. The order makes a difference when the
-@samp{-x} option is used.
+@samp{-x} option is used.
+
+@menu
+* File Options:: Choosing Files
+* Mode Options:: Choosing Modes
+_if__(!_GENERIC__)
+_include__(gdbinv-m.m4)_dnl__
+_fi__(!_GENERIC__)
+@end menu
+
+@node File Options, Mode Options, Invoking _GDBN__, Invoking _GDBN__
+@subsection Choosing Files
-@node File Options, Mode Options, Invocation, Invocation
-@section Options and Arguments to Choose Files
+When _GDBN__ starts, it reads any arguments other than options as
+specifying an executable file and core file (or process ID). This is
+the same as if the arguments were specified by the @samp{-se} and
+@samp{-c} options respectively. (_GDBN__ reads the first argument
+that does not have an associated option flag as equivalent to the
+@samp{-se} option followed by that argument; and the second argument
+that does not have an associated option flag, if any, as equivalent to
+the @samp{-c} option followed by that argument.)
-As shown above, any arguments other than options specify an executable
-file and core file; that is, the first argument encountered with no
-associated option flag is equivalent to a @samp{-se} option, and the
-second, if any, is equivalent to a @samp{-c} option.
+Many options have both long and short forms; both are shown in the
+following list. _GDBN__ also recognizes the long forms if you truncate
+them, so long as enough of the option is present to be unambiguous.
+(If you prefer, you can flag option arguments with @samp{--} rather
+than @samp{-}, though we illustrate the more usual convention.)
@table @code
-@item -s @var{file}
+@item -symbols=@var{file}
+@itemx -s @var{file}
Read symbol table from file @var{file}.
-@item -e @var{file}
+@item -exec=@var{file}
+@itemx -e @var{file}
Use file @var{file} as the executable file to execute when
appropriate, and for examining pure data in conjunction with a core
dump.
-@item -se @var{file}
+@item -se=@var{file}
Read symbol table from file @var{file} and use it as the executable
file.
-@item -c @var{file}
+@item -core=@var{file}
+@itemx -c @var{file}
Use file @var{file} as a core dump to examine.
-@item -x @var{file}
+@item -command=@var{file}
+@itemx -x @var{file}
Execute _GDBN__ commands from file @var{file}. @xref{Command Files}.
-@item -d @var{directory}
+@item -directory=@var{directory}
+@itemx -d @var{directory}
Add @var{directory} to the path to search for source files.
+
+@item -m
+@itemx -mapped
+@emph{Warning: this option depends on operating system facilities that are not
+supported on all systems.}@*
+If memory-mapped files are available on your system through the @code{mmap}
+system call, you can use this option
+to cause _GDBN__ to write the symbols from your
+program into a reusable file in the current directory. If the program you are debugging is
+called @file{/tmp/fred}, the mapped symbol file will be @file{./fred.syms}.
+Future _GDBN__ debugging sessions will notice the presence of this file,
+and will quickly map in symbol information from it, rather than reading
+the symbol table from the executable program.
+
+The @file{.syms} file is specific to the host machine on which _GDBN__ is run.
+It holds an exact image of _GDBN__'s internal symbol table. It cannot be
+shared across multiple host platforms.
+
+@item -r
+@itemx -readnow
+Read each symbol file's entire symbol table immediately, rather than
+the default, which is to read it incrementally as it is needed.
+This makes startup slower, but makes future operations faster.
@end table
-@node Mode Options, Remote i960-Nindy, File Options, Invocation
-@section Options to Choose Modes
+The @code{-mapped} and @code{-readnow} options are typically combined in order to
+build a @file{.syms} file that contains complete symbol information.
+A simple GDB invocation to do nothing but build a @file{.syms} file for future
+use is:
+
+@example
+ gdb -batch -nx -mapped -readnow programname
+@end example
+
+_if__(!_GENERIC__)
+@node Mode Options, Mode Options, File Options, Invoking _GDBN__
+_fi__(!_GENERIC__)
+_if__(_GENERIC__)
+@node Mode Options, , File Options, Invoking _GDBN__
+_fi__(_GENERIC__)
+@subsection Choosing Modes
+
+You can run _GDBN__ in various alternative modes---for example, in
+batch mode or quiet mode.
@table @code
@item -nx
-Do not execute commands from the init files @file{._GDBP__init}.
+@itemx -n
+Do not execute commands from any @file{_GDBINIT__} initialization files.
Normally, the commands in these files are executed after all the
-command options and arguments have been processed. @xref{Command
-Files}.
+command options and arguments have been processed.
+@xref{Command Files}.
-@item -q
+@item -quiet
+@itemx -q
``Quiet''. Do not print the introductory and copyright messages. These
-messages are also suppressed in batch mode, or if an executable file name is
-specified on the _GDBN__ command line.
+messages are also suppressed in batch mode.
@item -batch
-Run in batch mode. Exit with code @code{0} after processing all the command
-files specified with @samp{-x} (and @file{._GDBP__init}, if not inhibited).
+Run in batch mode. Exit with status @code{0} after processing all the command
+files specified with @samp{-x} (and @file{_GDBINIT__}, if not inhibited).
Exit with nonzero status if an error occurs in executing the _GDBN__
-commands in the command files.
+commands in the command files.
Batch mode may be useful for running _GDBN__ as a filter, for example to
download and run a program on another computer; in order to make this
-more useful, the message
+more useful, the message
+
@example
Program exited normally.
@end example
+
@noindent
(which is ordinarily issued whenever a program running under _GDBN__ control
terminates) is not issued when running in batch mode.
+@item -cd=@var{directory}
+Run _GDBN__ using @var{directory} as its working directory,
+instead of the current directory.
+
+_if__(_LUCID__)
+@item -context @var{authentication}
+When the Energize programming system starts up _GDBN__, it uses this
+option to trigger an alternate mode of interaction.
+@var{authentication} is a pair of numeric codes that identify _GDBN__
+as a client in the Energize environment. Avoid this option when you run
+_GDBN__ directly from the command line. See @ref{Energize,,Using
+_GDBN__ with Energize} for more discussion of using _GDBN__ with Energize.
+_fi__(_LUCID__)
+
@item -fullname
-This option is used when Emacs runs _GDBN__ as a subprocess. It tells _GDBN__
+@itemx -f
+Emacs sets this option when it runs _GDBN__ as a subprocess. It tells _GDBN__
to output the full file name and line number in a standard,
recognizable fashion each time a stack frame is displayed (which
-includes each time the program stops). This recognizable format looks
+includes each time your program stops). This recognizable format looks
like two @samp{\032} characters, followed by the file name, line number
and character position separated by colons, and a newline. The
Emacs-to-_GDBN__ interface program uses the two @samp{\032} characters as
a signal to display the source code for the frame.
@item -b @var{bps}
-Set the line speed (baud rate or bps) of any serial interface used by
-_GDBN__ for remote debugging.
-@end table
+Set the line speed (baud rate or bits per second) of any serial
+interface used by _GDBN__ for remote debugging.
-_if__(_I960__)
-@node i960-Nindy Remote,,,
-@section _GDBN__ with a Remote Intel 960 (Nindy)
+@item -tty=@var{device}
+Run using @var{device} for your program's standard input and output.
+@c FIXME: kingdon thinks there is more to -tty. Investigate.
+@end table
-``Nindy'' is the name of a Rom Monitor program for Intel 960 target
-systems. When _GDBN__ is configured to control a remote Intel 960 using
-Nindy, you can tell _GDBN__ how to connect to the 960 in several ways:
+_if__(!_GENERIC__)
+_include__(gdbinv-s.m4)
+_fi__(!_GENERIC__)
+@node Leaving _GDBN__, Shell Commands, Invoking _GDBN__, Invocation
+@section Leaving _GDBN__
+@cindex exiting _GDBN__
-@itemize @bullet
-@item
-Through command line options specifying device, baud rate, and protocol;
+@table @code
+@item quit
+@kindex quit
+@kindex q
+To exit _GDBN__, use the @code{quit} command (abbreviated @code{q}), or type
+an end-of-file character (usually @kbd{C-d}).
+@end table
-@item
-By responding to a prompt on startup;
+@cindex interrupt
+An interrupt (often @kbd{C-c}) will not exit from _GDBN__, but rather
+will terminate the action of any _GDBN__ command that is in progress and
+return to _GDBN__ command level. It is safe to type the interrupt
+character at any time because _GDBN__ does not allow it to take effect
+until a time when it is safe.
-@item
-By using the @samp{target} command at any point during your _GDBN__ session.
-@end itemize
+If you have been using _GDBN__ to control an attached process or device, you
+can release it with the @code{detach} command; @pxref{Attach,
+,Debugging an Already-Running Process}..
-@node Nindy Startup,,,
-@subsection Startup with Nindy
+@node Shell Commands, , Leaving _GDBN__, Invocation
+@section Shell Commands
-The command-line options for Nindy are detailed below. If you simply
-start @code{_GDBP__} without using options to specify a serial port, you are
-prompted for it, @emph{before} you reach the ordinary _GDBN__ prompt:
-@example
-Attach /dev/ttyNN -- specify NN, or "quit" to quit:
-@end example
-@noindent
-You can, if you choose, simply start up with no Nindy connection by
-responding to the prompt with an empty line. If you do this, and later
-wish to attach to Nindy, use @samp{target} (@pxref{Target Commands}).
+If you need to execute occasional shell commands during your
+debugging session, there is no need to leave or suspend _GDBN__; you can
+just use the @code{shell} command.
-@node Nindy Options,,,
-@subsection Options for Nindy
+@table @code
+@item shell @var{command string}
+@kindex shell
+@cindex shell escape
+Directs _GDBN__ to invoke an inferior shell to execute @var{command
+string}. If it exists, the environment variable @code{SHELL} is used
+for the name of the shell to run. Otherwise _GDBN__ uses
+@code{/bin/sh}.
+@end table
-These are the startup options for beginning your _GDBN__ session with a
-Nindy-960 board attached:
+The utility @code{make} is often needed in development environments.
+You do not have to use the @code{shell} command for this purpose in _GDBN__:
@table @code
-@item -r @var{port}
-Specify the serial port name of a serial interface to be used to connect
-to the target system. This option is only available when _GDBN__ is
-configured for the Intel 960 target architecture. You may specify
-@var{port} as any of: a full pathname (e.g. @samp{-r /dev/ttya}), a
-device name in @samp{/dev} (e.g. @samp{-r ttya}), or simply the unique
-suffix for a specific @code{tty} (e.g. @samp{-r a}).
-
-@item -O
-(An uppercase letter ``O'', not a zero.) Specify that _GDBN__ should use
-the ``old'' Nindy monitor protocol to connect to the target system.
-This option is only available when _GDBN__ is configured for the Intel 960
-target architecture.
-
-@quotation
-@emph{Warning:} if you specify @samp{-O}, but are actually trying to
-connect to a target system using the current protocol, the connection
-will fail appearing to be a speed mismatch, and _GDBN__ will repeatedly
-attempt to reconnect at several different line speeds. You can abort
-this process with an interrupt.
-@end quotation
-
-@item -brk
-Specify that _GDBN__ should first send a @samp{BREAK} signal to the target
-system, in an attempt to reset it, before connecting to a Nindy target.
-This option is only available when _GDBN__ is configured for the Intel 960
-target architecture.
-
-@quotation
-@emph{Warning:} Many target systems do not have the hardware that this
-requires; it only works with a few boards.
-@end quotation
-
+@item make @var{make-args}
+@kindex make
+@cindex calling make
+Causes _GDBN__ to execute an inferior @code{make} program with the specified
+arguments. This is equivalent to @samp{shell make @var{make-args}}.
@end table
-The standard @samp{-b} option controls the line speed used on the serial
-port.
-_fi__(_I960__)
-
-_if__(_AMD29K__)
-@node EB29K Remote,,,
-@section Starting _GDBN__ with a Remote EB29K
-
-@cindex EB29K board
-@cindex running 29K programs
-@cindex 29K
-
-To use _GDBN__ from a Unix system to run programs on AMD's EB29K
-board in a PC, you must first connect a serial cable between the PC
-and a serial port on the Unix system. In the following, we assume
-you've hooked the cable between the PC's @samp{COM1} port and
-@samp{/dev/ttya} on the Unix system.
-
-@node Comms (EB29K),,,
-@subsection Communications Setup
-The next step is to set up the PC's port, by doing something like the
-following in DOS on the PC:
-@example
-C> MODE com1:9600,n,8,1,none
-@end example
-@noindent
-This example---run on an MS DOS 4.0 system---sets the PC port to 9600
-bps, no parity, eight data bits, one stop bit, and no ``retry'' action;
-you must match the communications parameters when establishing the Unix
-end of the connection as well.
-@c FIXME: Who knows what this "no retry action" crud from the DOS manual may
-
-To give control of the PC to the Unix side of the serial line, type
-the following at the DOS console:
-@example
-C> CTTY com1
-@end example
-@noindent
-(Later, if you wish to return control to the DOS console, you can use
-the command @samp{CTTY con}---but you must send it over the device that
-had control, in our example over the @samp{com1} serial line).
-
-From the Unix host, use a communications program such as @code{tip} or
-@code{cu} to communicate with the PC; for example,
-@example
-cu -s 9600 -l /dev/ttya
-@end example
-@noindent
-The @code{cu} options shown specify, respectively, the linespeed and the
-serial port to use. If you use @code{tip} instead, the corresponding
-parameters must be entered in the ``remote'' descriptions file used by
-@code{tip}---normally the system table @file{/etc/remote}.
-@c FIXME: What if anything needs doing to match the "n,8,1,none" part of
-@c the DOS side's comms setup? cu can support -o (odd
-@c parity), -e (even parity)---apparently no settings for no parity or
-@c for character size. Taken from stty maybe...? John points out tip
-@c can set these as internal variables, eg ~s parity=none; man stty
-@c suggests that it *might* work to stty these options with stdin or
-@c stdout redirected... is it worth experimenting? Maybe if the literal
-
-@kindex EBMON
-Using the @samp{tip} or @samp{cu} connection, change the DOS working
-directory to the directory containing a copy of your 29K program, then
-start the PC program @samp{EBMON} (an EB29K control program supplied
-with your board by AMD):
-@example
-C> CD g:\usr\joe\work29k
-C> EBMON
-C> ~.
-@end example
-
-Then exit the @code{cu} or @code{tip} program (done in the example by
-typing @code{~.}). @code{EBMON} will keep running, ready for _GDBN__ to
-take over.
-
-For this example, we've assumed what is probably the most convenient
-way to make sure the same 29K program is on both the PC and the Unix
-system: a PC/NFS connection that establishes ``drive'' @code{g:} on the
-PC as a file system on the Unix host. If you don't have PC/NFS or
-something similar connecting the two systems, you must arrange some
-other way---perhaps floppy-disk transfer---of getting the 29K program
-from the Unix system to the PC; _GDBN__ will @emph{not} download it over the
-serial line.
-
-@node _GDBP__-EB29K
-@subsection EB29K cross-debugging
-Finally, @code{cd} to the directory containing an image of your 29K
-program on the Unix system, and start _GDBN__---specifying as argument the
-name of your 29K program:
-@example
-cd /usr/joe/work29k
-_GDBP__ myfoo
-@end example
-Now you can use the @code{target} command:
-@example
-target amd-eb /dev/ttya 9600 MYFOO
-@end example
-@c FIXME: test above 'target amd-eb' as spelled, with caps! caps are meant to
-@c emphasize that this is the name as seen by DOS (since I think DOS is
+@node Commands, Running, Invocation, Top
+@chapter _GDBN__ Commands
-@noindent
-In this example, we've assumed your program is in a file called
-@samp{myfoo}. Note that the filename given as the last argument to
-@samp{target amd-eb} should be the name of the program as it appears to DOS.
-In our example it is simply @samp{MYFOO}, but in general it can include
-a DOS path, and depending on your transfer mechanism may not resemble
-the name on the Unix side.
-
-At this point, you can set any breakpoints you wish; when you're ready
-to see your program run on the 29K board, use the _GDBN__ command
-@example
-run
-@end example
+You can abbreviate a _GDBN__ command to the first few letters of the command
+name, if that abbreviation is unambiguous; and you can repeat certain
+_GDBN__ commands by typing just @key{RET}. You can also use the @key{TAB}
+key to get _GDBN__ to fill out the rest of a word in a command (or to
+show you the alternatives available, if there's more than one possibility).
-To stop debugging the remote program, use the _GDBN__ @samp{detach}
-command.
-
-To return control of the PC to its console, use @code{tip} or @code{cu}
-once again, after your _GDBN__ session has concluded, to attach to
-@code{EBMON}. You can then type the command @samp{q} to shut down
-@code{EBMON}, returning control to the DOS command-line interpreter.
-Type @samp{CTTY con} to return command input to the main DOS console,
-and type @samp{~.} to leave @code{tip} or @code{cu}.
-
-@node Remote Log, , Remote Commands, Remote
-@subsection Remote Log
-@kindex eb.log
-@cindex log file for EB29K
-The @samp{target amd-eb} command creates a file @file{eb.log} in the
-current working directory, to help debug problems with the connection.
-@file{eb.log} records all the output from @code{EBMON}, including echoes
-of the commands sent to it. Running @samp{tail -f} on this file in
-another window often helps to debug trouble with @code{EBMON}, or
-unexpected events on the PC side of the connection.
-_fi__(_AMD29K__)
+@menu
+* Command Syntax:: Command Syntax
+* Completion:: Command Completion
+* Help:: Getting Help
+@end menu
-@node User Interface, Files, Invocation, Top
-@chapter _GDBN__ Commands and Displays
+@node Command Syntax, Completion, Commands, Commands
+@section Command Syntax
A _GDBN__ command is a single line of input. There is no limit on how long
it can be. It starts with a command name, which is followed by arguments
whose meaning depends on the command name. For example, the command
-@samp{step} accepts an argument which is the number of times to step,
-as in @samp{step 5}. You can also use the @samp{step} command with
+@code{step} accepts an argument which is the number of times to step,
+as in @samp{step 5}. You can also use the @code{step} command with
no arguments. Some command names do not allow any arguments.
@cindex abbreviation
_GDBN__ command names may always be truncated if that abbreviation is
unambiguous. Other possible command abbreviations are listed in the
-documentation of the individual commands. Sometimes even ambiguous
-abbreviations are allowed; for example, @samp{s} is specially defined as
-equivalent to @samp{step} even though there are other commands whose
-names start with @samp{s}.
+documentation for individual commands. In some cases, even ambiguous
+abbreviations are allowed; for example, @code{s} is specially defined as
+equivalent to @code{step} even though there are other commands whose
+names start with @code{s}. You can test abbreviations by using them as
+arguments to the @code{help} command.
@cindex repeating commands
-A blank line as input to _GDBN__ means to repeat the previous command.
-Certain commands will not repeat this way; these are commands for which
-unintentional repetition might cause trouble and which you are unlikely
-to want to repeat. Certain others (@samp{list} and @samp{x}) act
-differently when repeated because that is more useful.
+@kindex RET
+A blank line as input to _GDBN__ (typing just @key{RET}) means to
+repeat the previous command. Certain commands (for example, @code{run})
+will not repeat this way; these are commands for which unintentional
+repetition might cause trouble and which you are unlikely to want to
+repeat.
+
+The @code{list} and @code{x} commands, when you repeat them with
+@key{RET}, construct new arguments rather than repeating
+exactly as typed. This permits easy scanning of source or memory.
+
+_GDBN__ can also use @key{RET} in another way: to partition lengthy
+output, in a way similar to the common utility @code{more}
+(@pxref{Screen Size}). Since it is easy to press one @key{RET} too many
+in this situation, _GDBN__ disables command repetition after any command
+that generates this sort of display.
@kindex #
@cindex comment
-A line of input starting with @samp{#} is a comment; it does nothing.
-This is useful mainly in command files (@xref{Command Files}).
-
-@cindex online documentation
-@kindex help
-@table @code
-@item help
-@itemx help @var{category}
-@itemx help @var{command}
-You can always ask _GDBN__ itself for information on its commands, using the
-command @samp{help}. With a command name as argument, it will display a
-paragraph on how to use the command. Used with no arguments,
-@samp{help} displays a short list of named categories of commands; you
-can then use @samp{help @var{category}} to list the individual commands
-in a category.
-
-@kindex info version
-@item info version
-As _GDBN__ evolves, new commands are introduced, and old ones may wither
-away. If multiple versions of _GDBN__ are in use at your site, it may
-occasionally be useful to make sure what version of _GDBN__ you're running.
-_GDBN__ announces its version whenever it starts up; but you can make it
-repeat this information with the @samp{info version} command.
-@end table
-
-@cindex prompt
-_GDBN__ indicates its readiness to read a command by printing a string
-called the @dfn{prompt}. This string is normally @samp{(_GDBP__)}. You can
-change the prompt string with the @samp{set prompt} command. For
-instance, when debugging _GDBN__ with _GDBN__, it is useful to change the prompt
-in one of the _GDBN__s so that you tell which one you are talking to.
+A line of input starting with @kbd{#} is a comment; it does nothing.
+This is useful mainly in command files (@pxref{Command Files}).
-@table @code
-@item set prompt @var{newprompt}
-@kindex set prompt
-Directs _GDBN__ to use @var{newprompt} as its prompt string henceforth.
-@kindex show prompt
-@item show prompt
-Prints a line of the form: @samp{Gdb's prompt is: @var{your-prompt}}
-@end table
+@node Completion, Help, Command Syntax, Commands
+@section Command Completion
-@cindex exiting _GDBN__
-@kindex quit
-To exit _GDBN__, use the @samp{quit} command (abbreviated @samp{q}), or type
-an end-of-file character (usually @ctrl{d}). An interrupt (often
-@ctrl{c}) will not exit from _GDBN__, but rather will terminate the action
-of any _GDBN__ command that is in progress and return to _GDBN__ command level.
-It is safe to type the interrupt character at any time because _GDBN__ does
-not allow it to take effect until a time when it is safe.
+@cindex completion
+@cindex word completion
+_GDBN__ can fill in the rest of a word in a command for you, if there's
+only one possibility; it can also show you what the valid possibilities
+are for the next word in a command, at any time. This works for _GDBN__
+commands, _GDBN__ subcommands, and the names of symbols in your program.
-@cindex readline
-@cindex command line editing
-@cindex history substitution
-_GDBN__ reads its input commands via the @code{readline} interface. This
-GNU library provides consistent behavior for programs which provide a
-command line interface to the user. Advantages are @samp{emacs}-style
-or @samp{vi}-style inline editing of commands, @samp{csh}-like history
-substitution, and a storage and recall of command history across
-debugging sessions.
+Press the @key{TAB} key whenever you want _GDBN__ to fill out the rest
+of a word. If there's only one possibility, _GDBN__ will fill in the
+word, and wait for you to finish the command (or press @key{RET} to
+enter it). For example, if you type
-You may control the behavior of command line editing in _GDBN__ with the
-command @samp{set}. You may check the status of any of these settings
-with the command @samp{show}.
+@example
+(_GDBP__) info bre@key{TAB}
+@end example
-@table @code
-@kindex set editing
-@cindex editing
-@item set editing
-@itemx set editing on
-Enable command line editing (enabled by default).
+@noindent
+_GDBN__ fills in the rest of the word @samp{breakpoints}, since that's
+the only @code{info} subcommand beginning with @samp{bre}:
-@item set editing off
-Disable command line editing.
+@example
+(_GDBP__) info breakpoints
+@end example
-@kindex show editing
-@item show editing
-Show whether command line editing is enabled.
+@noindent
+You can either press @key{RET} at this point, to run the @code{info
+breakpoints} command, or backspace and enter something else, if
+@samp{breakpoints} doesn't look like the command you expected. (If you
+were sure you wanted @code{info breakpoints} in the first place, you
+might as well just type @key{RET} immediately after @samp{info bre},
+to exploit command abbreviations rather than command completion).
+
+If there is more than one possibility for the next word when you press
+@key{TAB}, _GDBN__ will sound a bell. You can either supply more
+characters and try again, or just press @key{TAB} a second time, and
+_GDBN__ will display all the possible completions for that word. For
+example, you might want to set a breakpoint on a subroutine whose name
+begins with @samp{mak}, but when you type @kbd{b mak@key{TAB}} _GDBN__
+just sounds the bell. Typing @key{TAB} again will display all the
+function names in your program that begin with those characters, for
+example:
-@cindex history file
-@kindex set history file
-@item set history file @var{filename}
-Set the name of the _GDBN__ command history file to @samp{filename}. This is
-the file from which _GDBN__ will read an initial command history
-list or to which it will write this list when it exits. This list is
-accessed through history expansion or through the history
-command editing characters listed below. This file defaults to the
-value of the environmental variable @code{GDBHISTFILE}, or to
-@code{./.gdb_history} if this variable is not set.
+@example
+(_GDBP__) b mak@key{TAB}
+make_a_section_from_file make_environ
+make_abs_section make_function_type
+make_blockvector make_pointer_type
+make_cleanup make_reference_type
+make_command make_symbol_completion_list
+(GDBP__) b mak
+@end example
-@cindex history write
-@kindex set history write
-@item set history write
-@itemx set history write on
-Make _GDBN__ record command history in a file, whose name may be specified with the
-@samp{set history file} command. By default, this option is disabled.
+@noindent
+After displaying the available possibilities, _GDBN__ copies your
+partial input (@samp{b mak} in the example) so you can finish the
+command.
-@item set history write off
-Make _GDBN__ stop recording command history in a file.
+If you just want to see the list of alternatives in the first place, you
+can press @kbd{M-?} rather than pressing @key{TAB} twice. (@kbd{M-?}
+means @kbd{@key{META} ?}. If your keyboard doesn't have a Meta shift,
+you can type @key{ESC} followed by @kbd{?} instead.)
+
+@cindex quotes in commands
+@cindex completion of quoted strings
+Sometimes the string you need, while logically a ``word'', may contain
+parentheses or other characters that _GDBN__ normally excludes from its
+notion of a word. To permit word completion to work in this situation,
+you may enclose words in @code{'} (single quote marks) in _GDBN__ commands.
+
+The most likely situation where you might need this is in typing the
+name of a C++ function. This is because C++ allows function overloading
+(multiple definitions of the same function, distinguished by argument
+type). For example, you may need to distinguish whether you mean
+@samp{name(int)} or @samp{name(float)} when you want to set a
+breakpoint. To use the word-completion facilities in this situation,
+type a single quote @code{'} at the beginning of the function name.
+This alerts _GDBN__ that it may need to consider more information than
+usual when you press @key{TAB} or @kbd{M-?} to request word completion:
-@cindex history size
-@kindex set history size
-@item set history size @var{size}
-Set the number of commands which _GDBN__ will keep in its history list.
-This defaults to the value of the environmental variable
-@code{HISTSIZE}, or to 256 if this variable is not set.
-@end table
+@example
+(_GDBP__) b 'name(@key{M-?}
+name(int) name(float)
+(_GDBP__) b 'name
+@end example
-@cindex history expansion
-History expansion assigns special meaning to the character @samp{!}
-(@pxref{Event Designators}). Since @samp{!} is also the logical not
-operator in C, history expansion is off by default. If you decide to
-enable history expansion with the @samp{set history expansion on}
-command, you may sometimes need to follow @samp{!} (when it is used as
-logical not, in an expression) with a space or a tab to prevent it from
-being expanded. The @code{readline} history facilities will not attempt
-substitution on the strings @samp{!=} and @samp{!(}, even when history
-expansion is enabled.
+@node Help, , Completion, Commands
+@section Getting Help
+@cindex online documentation
+@kindex help
-The commands to control history expansion are:
+You can always ask _GDBN__ itself for information on its commands, using the
+command @code{help}.
@table @code
+@item help
+@itemx h
+@kindex h
+You can use @code{help} (abbreviated @code{h}) with no arguments to
+display a short list of named classes of commands:
-@kindex set history expansion
-@item set history expansion on
-@itemx set history expansion
-Enable history expansion. History expansion is off by default.
-
-@item set history expansion off
-Disable history expansion.
-
-The @code{readline} code comes with more complete documentation of
-editing and history expansion features. Users unfamiliar with @samp{emacs}
-or @samp{vi} may wish to read it. @xref{Command Line Editing}.
-
-@kindex show history
-@item show history
-@itemx show history file
-@itemx show history write
-@itemx show history size
-@itemx show history expansion
-These commands display the state of the _GDBN__ history parameters.
-@samp{show history} by itself displays all four states.
+@smallexample
+(_GDBP__) help
+List of classes of commands:
+
+running -- Running the program
+stack -- Examining the stack
+data -- Examining data
+breakpoints -- Making program stop at certain points
+files -- Specifying and examining files
+status -- Status inquiries
+support -- Support facilities
+user-defined -- User-defined commands
+aliases -- Aliases of other commands
+obscure -- Obscure features
+
+Type "help" followed by a class name for a list of
+commands in that class.
+Type "help" followed by command name for full
+documentation.
+Command name abbreviations are allowed if unambiguous.
+(_GDBP__)
+@end smallexample
-@kindex show
-@kindex info set
-@item show
-@itemx info set
-This chapter introduces a number of internal _GDBN__ variables that you
-can control with the @samp{set} command, and display with the
-@samp{show} command. A number of others are introduced throughout the
-manual. To display all the settable parameters and their current
-values, you can use @samp{show} with no arguments; you may also use
-@samp{info set}. Both commands produce the same display.
+@item help @var{class}
+Using one of the general help classes as an argument, you can get a
+list of the individual commands in that class. For example, here is the
+help display for the class @code{status}:
-@end table
+@smallexample
+(_GDBP__) help status
+Status inquiries.
-@table @code
-@kindex info editing
-@item info editing
-Display the last ten commands in the command history.
+List of commands:
-@item info editing @var{n}
-Print ten commands centered on command number @var{n}.
+show -- Generic command for showing things set with "set"
+info -- Generic command for printing status
-@item info editing +
-Print ten commands just after the commands last printed.
+Type "help" followed by command name for full
+documentation.
+Command name abbreviations are allowed if unambiguous.
+(_GDBP__)
+@end smallexample
+@item help @var{command}
+With a command name as @code{help} argument, _GDBN__ will display a
+short paragraph on how to use that command.
@end table
-Occasionally it is useful to execute a shell command from within _GDBN__.
-This can be done with the @samp{shell} command.
+In addition to @code{help}, you can use the _GDBN__ commands @code{info}
+and @code{show} to inquire about the state of your program, or the state
+of _GDBN__ itself. Each command supports many topics of inquiry; this
+manual introduces each of them in the appropriate context. The listings
+under @code{info} and under @code{show} in the Index point to
+all the sub-commands. @xref{Index}.
+@c @group
@table @code
-@item shell @var{command string}
-@kindex shell
-@cindex shell escape
-Directs _GDBN__ to invoke an inferior shell to execute @var{command string}.
-The environment variable @code{SHELL} is used if it exists, otherwise _GDBN__
-uses @samp{/bin/sh}.
-@end table
+@item info
+@kindex info
+@kindex i
+This command (abbreviated @code{i}) is for describing the state of your
+program; for example, it can list the arguments given to your program
+(@code{info args}), the registers currently in use (@code{info
+registers}), or the breakpoints you have set (@code{info breakpoints}).
+You can get a complete list of the @code{info} sub-commands with
+@w{@code{help info}}.
-The utility @samp{make} is often needed in development environments.
-You don't have to use the @samp{shell} command for this purpose in _GDBN__:
+@kindex show
+@item show
+In contrast, @code{show} is for describing the state of _GDBN__ itself.
+You can change most of the things you can @code{show}, by using the
+related command @code{set}; for example, you can control what number
+system is used for displays with @code{set radix}, or simply inquire
+which is currently in use with @code{show radix}.
-@table @code
-@item make @dots{}
-@kindex make
-@cindex calling make
-Causes _GDBN__ to execute an inferior @code{make} program with the specified
-arguments. This is equivalent to @samp{shell make @dots{}}.
+@kindex info set
+To display all the settable parameters and their current
+values, you can use @code{show} with no arguments; you may also use
+@code{info set}. Both commands produce the same display.
+@c FIXME: "info set" violates the rule that "info" is for state of
+@c FIXME...program. Ck w/ GNU: "info set" to be called something else,
+@c FIXME...or change desc of rule---eg "state of prog and debugging session"?
@end table
+@c @end group
-@cindex screen size
-@cindex pauses in output
-Certain commands to _GDBN__ may produce large amounts of information output
-to the screen. To help you read all of it, _GDBN__ pauses and asks you for
-input at the end of each page of output. Type @key{RET} when you want
-to continue the output. Normally _GDBN__ knows the size of the screen from
-the termcap data base together with the value of the @code{TERM}
-environment variable and the @code{stty rows} and @code{stty cols}
-settings. If this is not correct, you can override it with
-the @samp{set screen-height} and @samp{set screen-width} commands:
-
-_GDBN__ also uses the screen width setting to determine when to wrap lines
-of output. Depending what is being printed, it tries to break the
-line at a readable place, rather than simply letting it overflow onto
-the following line.
+Here are three miscellaneous @code{show} subcommands, all of which are
+exceptional in lacking corresponding @code{set} commands:
@table @code
-@item set screen-height @var{lpp}
-@itemx show screen-height
-@itemx set screen-width @var{cpl}
-@itemx show screen-width
-@kindex set screen-height
-@kindex set screen-width
-@kindex show screen-width
-@kindex show screen-height
-These @samp{set} commands specify a screen height of @var{lpp} lines and
-a screen width of @var{cpl} characters. The associated @samp{show}
-commands display the current settings.
-
-If you specify a height of zero lines, _GDBN__ will not pause during output
-no matter how long the output is. This is useful if output is to a file
-or to an editor buffer.
+@kindex show version
+@cindex version number
+@item show version
+Show what version of _GDBN__ is running. You should include this
+information in _GDBN__ bug-reports. If multiple versions of _GDBN__ are in
+use at your site, you may occasionally want to make sure what version
+of _GDBN__ you are running; as _GDBN__ evolves, new commands are introduced,
+and old ones may wither away. The version number is also announced
+when you start _GDBN__ with no arguments.
+
+@kindex show copying
+@item show copying
+Display information about permission for copying _GDBN__.
+
+@kindex show warranty
+@item show warranty
+Display the GNU ``NO WARRANTY'' statement.
@end table
-@cindex number representation
-@cindex entering numbers
-You can always enter numbers in octal, decimal, or hexadecimal in _GDBN__ by
-the usual conventions: octal numbers begin with @samp{0}, decimal
-numbers end with @samp{.}, and hexadecimal numbers begin with @samp{0x}.
-Numbers that begin with none of these are, by default, entered in base
-10; likewise, the default display for numbers---when no particular
-format is specified---is base 10. You can change the default base for
-both input and output with the @samp{set radix} command.
+@node Running, Stopping, Commands, Top
+@chapter Running Programs Under _GDBN__
-@table @code
-@kindex set radix
-@item set radix @var{base}
-Set the default base for numeric input and display. Supported choices
-for @var{base} are decimal 8, 10, 16. @var{base} must itself be
-specified either unambiguously or using the current default radix; for
-example, any of
+To debug a program, you must run it under _GDBN__.
-@example
-set radix 012
-set radix 10.
-set radix 0xa
-@end example
+@menu
+* Compilation:: Compiling for Debugging
+* Starting:: Starting your Program
+* Arguments:: Your Program's Arguments
+* Environment:: Your Program's Environment
+* Working Directory:: Your Program's Working Directory
+* Input/Output:: Your Program's Input and Output
+* Attach:: Debugging an Already-Running Process
+* Kill Process:: Killing the Child Process
+* Process Information:: Additional Process Information
+@end menu
-@noindent
-will set the base to decimal. On the other hand, @samp{set radix 10}
-will leave the radix unchanged no matter what it was.
+@node Compilation, Starting, Running, Running
+@section Compiling for Debugging
-@kindex show radix
-@item show radix
-Display the current default base for numeric input and display.
+In order to debug a program effectively, you need to generate
+debugging information when you compile it. This debugging information
+is stored in the object file; it describes the data type of each
+variable or function and the correspondence between source line numbers
+and addresses in the executable code.
-@end table
+To request debugging information, specify the @samp{-g} option when you run
+the compiler.
-By default, _GDBN__ is silent about its inner workings. If you are running
-on a slow machine, you may want to use the @samp{set verbose} command.
-It will make _GDBN__ tell you when it does a lengthy internal operation, so
-you won't think it has crashed.
+Many C compilers are unable to handle the @samp{-g} and @samp{-O}
+options together. Using those compilers, you cannot generate optimized
+executables containing debugging information.
+
+_GCC__, the GNU C compiler, supports @samp{-g} with or without
+@samp{-O}, making it possible to debug optimized code. We recommend
+that you @emph{always} use @samp{-g} whenever you compile a program.
+You may think your program is correct, but there is no sense in pushing
+your luck.
+
+@cindex optimized code, debugging
+@cindex debugging optimized code
+When you debug a program compiled with @samp{-g -O}, remember that the
+optimizer is rearranging your code; the debugger will show you what's
+really there. Don't be too surprised when the execution path doesn't
+exactly match your source file! An extreme example: if you define a
+variable, but never use it, _GDBN__ will never see that
+variable---because the compiler optimizes it out of existence.
+
+Some things do not work as well with @samp{-g -O} as with just
+@samp{-g}, particularly on machines with instruction scheduling. If in
+doubt, recompile with @samp{-g} alone, and if this fixes the problem,
+please report it as a bug (including a test case!).
+
+Older versions of the GNU C compiler permitted a variant option
+@w{@samp{-gg}} for debugging information. _GDBN__ no longer supports this
+format; if your GNU C compiler has this option, do not use it.
-Currently, the messages controlled by @samp{set verbose} are those which
-announce that the symbol table for a source file is being read
-(@pxref{Files}, in the description of the command
-@samp{symbol-file}).
-@c The following is the right way to do it, but emacs 18.55 doesn't support
-@c @ref, and neither the emacs lisp manual version of texinfmt or makeinfo
-@c is released.
@ignore
-see @samp{symbol-file} in @ref{Files}).
+@comment As far as I know, there are no cases in which _GDBN__ will
+@comment produce strange output in this case. (but no promises).
+If your program includes archives made with the @code{ar} program, and
+if the object files used as input to @code{ar} were compiled without the
+@samp{-g} option and have names longer than 15 characters, _GDBN__ will get
+confused reading your program's symbol table. No error message will be
+given, but _GDBN__ may behave strangely. The reason for this problem is a
+deficiency in the Unix archive file format, which cannot represent file
+names longer than 15 characters.
+
+To avoid this problem, compile the archive members with the @samp{-g}
+option or use shorter file names. Alternatively, use a version of GNU
+@code{ar} dated more recently than August 1989.
@end ignore
-@table @code
-@kindex set verbose
-@item set verbose on
-Enables _GDBN__'s output of certain informational messages.
+@node Starting, Arguments, Compilation, Running
+@section Starting your Program
+@cindex starting
+@cindex running
-@item set verbose off
-Disables _GDBN__'s output of certain informational messages.
+@table @code
+@item run
+@itemx r
+@kindex run
+Use the @code{run} command to start your program under _GDBN__. You must
+first specify the program name
+_if__(_VXWORKS__)
+(except on VxWorks)
+_fi__(_VXWORKS__)
+with an argument to
+_GDBN__ (@pxref{Invocation, ,Getting In and Out of _GDBN__}), or by using the
+@code{file} or @code{exec-file} command (@pxref{Files, ,Commands to
+Specify Files}).
-@kindex show verbose
-@item show verbose
-Displays whether @samp{set verbose} is on or off.
@end table
-By default, if _GDBN__ encounters bugs in the symbol table of an object file,
-it prints a single message about each type of problem it finds, then
-shuts up. You can suppress these messages, or allow more than one such
-message to be printed if you want to see how frequent the problems are.
-@xref{Files}.
+If you are running your program in an execution environment that
+supports processes, @code{run} creates an inferior process and makes
+that process run your program. (In environments without processes,
+@code{run} jumps to the start of your program.)
-@table @code
-@kindex set complaints
-@item set complaints @var{limit}
-Permits _GDBN__ to output @var{limit} complaints about each type of unusual
-symbols before becoming silent about the problem. Set @var{limit} to
-zero to suppress all complaints; set it to a large number to prevent
-complaints from being suppressed.
+The execution of a program is affected by certain information it
+receives from its superior. _GDBN__ provides ways to specify this
+information, which you must do @emph{before} starting your program. (You
+can change it after starting your program, but such changes will only affect
+your program the next time you start it.) This information may be
+divided into four categories:
-@kindex show complaints
-@item show complaints
-Displays how many symbol complaints _GDBN__ is permitted to produce.
+@table @asis
+@item The @emph{arguments.}
+Specify the arguments to give your program as the arguments of the
+@code{run} command. If a shell is available on your target, the shell
+is used to pass the arguments, so that you may use normal conventions
+(such as wildcard expansion or variable substitution) in describing
+the arguments. In Unix systems, you can control which shell is used
+with the @code{SHELL} environment variable. @xref{Arguments, ,Your
+Program's Arguments}.
+
+@item The @emph{environment.}
+Your program normally inherits its environment from _GDBN__, but you can
+use the _GDBN__ commands @code{set environment} and @code{unset
+environment} to change parts of the environment that will be given to
+your program. @xref{Environment, ,Your Program's Environment}.
+
+@item The @emph{working directory.}
+Your program inherits its working directory from _GDBN__. You can set
+_GDBN__'s working directory with the @code{cd} command in _GDBN__.
+@xref{Working Directory, ,Your Program's Working Directory}.
+
+@item The @emph{standard input and output.}
+Your program normally uses the same device for standard input and
+standard output as _GDBN__ is using. You can redirect input and output
+in the @code{run} command line, or you can use the @code{tty} command to
+set a different device for your program.
+@xref{Input/Output, ,Your Program's Input and Output}.
+
+@cindex pipes
+@emph{Warning:} While input and output redirection work, you cannot use
+pipes to pass the output of the program you are debugging to another
+program; if you attempt this, _GDBN__ is likely to wind up debugging the
+wrong program.
@end table
-By default, _GDBN__ is cautious, and asks what sometimes seem to be a lot of
-stupid questions. For example, if you try to run a program which is
-already running:
-@example
+@c FIXME: Rewrite following paragraph, especially its third sentence.
+When you issue the @code{run} command, your program begins to execute
+immediately. @xref{Stopping, ,Stopping and Continuing}, for
+discussion of how to arrange for your program to stop. Once your
+program has been started by the @code{run} command (and then stopped),
+you may evaluate expressions that involve calls to functions in your
+program, using the @code{print} or @code{call} commands. @xref{Data,
+,Examining Data}.
+
+If the modification time of your symbol file has changed since the
+last time _GDBN__ read its symbols, _GDBN__ will discard its symbol table and
+re-read it. When it does this, _GDBN__ tries to retain your current
+breakpoints.
+
+@node Arguments, Environment, Starting, Running
+@section Your Program's Arguments
-(_GDBP__) run
-The program being debugged has been started already.
-Start it from the beginning? (y or n)
-@end example
+@cindex arguments (to your program)
+The arguments to your program can be specified by the arguments of the
+@code{run} command. They are passed to a shell, which expands wildcard
+characters and performs redirection of I/O, and thence to your program.
+_GDBN__ uses the shell indicated by your environment variable
+@code{SHELL} if it exists; otherwise, _GDBN__ uses @code{/bin/sh}.
-If you're willing to unflinchingly face the consequences of your own
-commands, you can disable this ``feature'':
+@code{run} with no arguments uses the same arguments used by the previous
+@code{run}, or those set by the @code{set args} command.
+@kindex set args
@table @code
-@kindex set caution
-@cindex flinching
-@cindex stupid questions
-@item set caution off
-Disables cautious questions.
-
-@item set caution on
-Enables cautious questions (the default).
+@item set args
+Specify the arguments to be used the next time your program is run. If
+@code{set args} has no arguments, @code{run} will execute your program
+with no arguments. Once you have run your program with arguments,
+using @code{set args} before the next @code{run} is the only way to run
+it again without arguments.
-@item show caution
-@kindex show caution
-Displays state of cautious questions.
+@item show args
+@kindex show args
+Show the arguments to give your program when it is started.
@end table
-@node Files, Compilation, User Interface, Top
-@chapter Specifying _GDBN__'s Files
+@node Environment, Working Directory, Arguments, Running
+@section Your Program's Environment
-@cindex core dump file
-@cindex executable file
-@cindex symbol table
-_GDBN__ needs to know the file name of the program to be debugged, both in
-order to read its symbol table and in order to start the program. To
-debug a core dump of a previous run, _GDBN__ must be told the file name of
-the core dump.
+@cindex environment (of your program)
+The @dfn{environment} consists of a set of environment variables and
+their values. Environment variables conventionally record such things as
+your user name, your home directory, your terminal type, and your search
+path for programs to run. Usually you set up environment variables with
+the shell and they are inherited by all the other programs you run. When
+debugging, it can be useful to try running your program with a modified
+environment without having to start _GDBN__ over again.
-The usual way to specify the executable and core dump file names is with
-the command arguments given when you start _GDBN__, as discussed in
-@pxref{Invocation}.
+@table @code
+@item path @var{directory}
+@kindex path
+Add @var{directory} to the front of the @code{PATH} environment variable
+(the search path for executables), for both _GDBN__ and your program.
+You may specify several directory names, separated by @samp{:} or
+whitespace. If @var{directory} is already in the path, it is moved to
+the front, so it will be searched sooner.
+
+You can use the string @samp{$cwd} to refer to whatever is the current
+working directory at the time _GDBN__ searches the path. If you use
+@samp{.} instead, it refers to the directory where you executed the
+@code{path} command. _GDBN__ fills in the current path where needed in
+the @var{directory} argument, before adding it to the search path.
+@c 'path' is explicitly nonrepeatable, but RMS points out it is silly to
+@c document that, since repeating it would be a no-op.
+
+@item show paths
+@kindex show paths
+Display the list of search paths for executables (the @code{PATH}
+environment variable).
+
+@item show environment @r{[}@var{varname}@r{]}
+@kindex show environment
+Print the value of environment variable @var{varname} to be given to
+your program when it starts. If you do not supply @var{varname},
+print the names and values of all environment variables to be given to
+your program. You can abbreviate @code{environment} as @code{env}.
-But occasionally it is necessary to change to a different file during a
-_GDBN__ session. Or you may run _GDBN__ and forget to specify the files you
-want to use. In these situations the _GDBN__ commands to specify new files
-are useful.
+@item set environment @var{varname} @r{[}=@r{]} @var{value}
+@kindex set environment
+Sets environment variable @var{varname} to @var{value}. The value
+changes for your program only, not for _GDBN__ itself. @var{value} may
+be any string; the values of environment variables are just strings, and
+any interpretation is supplied by your program itself. The @var{value}
+parameter is optional; if it is eliminated, the variable is set to a
+null value.
+@c "any string" here does not include leading, trailing
+@c blanks. Gnu asks: does anyone care?
-@table @code
-@item file @var{filename}
-@kindex file
-Use @var{filename} as the program to be debugged. It is read for its
-symbols, for getting the contents of pure memory, and it is the program
-executed when you use the @samp{run} command. If you do not specify a
-directory and the file is not found in _GDBN__'s working directory, _GDBN__ will
-use the environment variable @code{PATH} as a list of directories to
-search, just as the shell does when looking for a program to run.
+For example, this command:
-@samp{file} with no argument makes both executable file and symbol
-table become unspecified.
+@example
+set env USER = foo
+@end example
-@item exec-file @var{filename}
-@kindex exec-file
-Specify that the program to be run (but not the symbol table) is found
-in @var{filename}. _GDBN__ will search the environment variable @code{PATH}
-if necessary to locate the program.
+@noindent
+tells a Unix program, when subsequently run, that its user is named
+@samp{foo}. (The spaces around @samp{=} are used for clarity here; they
+are not actually required.)
-@item symbol-file @var{filename}
-@kindex symbol-file
-Read symbol table information from file @var{filename}. @code{PATH} is
-searched when necessary. Use the @samp{file} command to get both symbol
-table and program to run from the same file.
+@item unset environment @var{varname}
+@kindex unset environment
+Remove variable @var{varname} from the environment to be passed to your
+program. This is different from @samp{set env @var{varname} =};
+@code{unset environment} removes the variable from the environment,
+rather than assigning it an empty value.
+@end table
-@samp{symbol-file} with no argument clears out _GDBN__'s information on your
-program's symbol table.
+@node Working Directory, Input/Output, Environment, Running
+@section Your Program's Working Directory
-The @samp{symbol-file} command causes _GDBN__ to forget the contents of its
-convenience variables, the value history, and all breakpoints and
-auto-display expressions. This is because they may contain pointers to
-the internal data recording symbols and data types, which are part of
-the old symbol table data being discarded inside _GDBN__.
+@cindex working directory (of your program)
+Each time you start your program with @code{run}, it inherits its
+working directory from the current working directory of _GDBN__. _GDBN__'s
+working directory is initially whatever it inherited from its parent
+process (typically the shell), but you can specify a new working
+directory in _GDBN__ with the @code{cd} command.
-On some kinds of object files, the @samp{symbol-file} command does not
-actually read the symbol table in full right away. Instead, it scans
-the symbol table quickly to find which source files and which symbols
-are present. The details are read later, one source file at a time,
-when they are needed.
+The _GDBN__ working directory also serves as a default for the commands
+that specify files for _GDBN__ to operate on. @xref{Files, ,Commands to
+Specify Files}.
-The purpose of this two-stage reading strategy is to make _GDBN__ start up
-faster. For the most part, it is invisible except for occasional pauses
-while the symbol table details for a particular source file are being
-read. (The @samp{set verbose} command can turn these pauses into
-messages if desired. @xref{User Interface}).
+@table @code
+@item cd @var{directory}
+@kindex cd
+Set _GDBN__'s working directory to @var{directory}.
-When the symbol table is stored in COFF format, @samp{symbol-file} does
-read the symbol table data in full right away. We haven't implemented
-the two-stage strategy for COFF yet.
+@item pwd
+@kindex pwd
+Print _GDBN__'s working directory.
+@end table
-When _GDBN__ is configured for a particular environment, it will understand
-debugging information in whatever format is the standard generated for
-that environment; you may use either the GNU compiler _GCC__, or other
-compilers that adhere to the local conventions. Best results are
-usually obtained from _GCC__; for example, using _GCC__ you can generate
-debugging information for optimized code.
-
-While the symbol file is being read, _GDBN__ will occasionally encounter
-problems, such as symbol types it does not recognize, or known bugs in
-compiler output. By default, it prints one message about each such
-type of problem, no matter how many times the problem occurs. You can
-ask it to print more messages, to see how many times the problems occur,
-or can shut the messages off entirely, with the @samp{set
-complaints} command (@xref{User Interface}).
+@node Input/Output, Attach, Working Directory, Running
+@section Your Program's Input and Output
-The messages currently printed, and their meanings, are:
+@cindex redirection
+@cindex i/o
+@cindex terminal
+By default, the program you run under _GDBN__ does input and output to
+the same terminal that _GDBN__ uses. _GDBN__ switches the terminal to
+its own terminal modes to interact with you, but it records the terminal
+modes your program was using and switches back to them when you continue
+running your program.
@table @code
-@item inner block not inside outer block in @var{symbol}
+@item info terminal
+@kindex info terminal
+Displays _GDBN__'s recorded information about the terminal modes your
+program is using.
+@end table
-The symbol information shows where symbol scopes begin and end
-(such as at the start of a function or a block of statements). This
-error indicates that an inner scope block is not fully contained
-in its outer scope blocks. _GDBN__ circumvents the problem by treating
-the inner block as if it had the same scope as the outer block.
-@var{symbol} may be ``(don't know)'' if the outer block is not
-a function.
+You can redirect your program's input and/or output using shell
+redirection with the @code{run} command. For example,
-@item block at @var{address} out of order
+_0__@example
+run > outfile
+_1__@end example
-The symbol information for symbol scope blocks should occur in
-order of increasing addresses. This error indicates that it does not
-do so. _GDBN__ does not circumvent this problem, and will have trouble
-locating symbols in the source file whose symbols being read. (You
-can often determine what source file is affected by turning on
-@samp{info verbose}. @xref{User Interface}.)
+@noindent
+starts your program, diverting its output to the file @file{outfile}.
-@item bad block start address patched
+@kindex tty
+@cindex controlling terminal
+Another way to specify where your program should do input and output is
+with the @code{tty} command. This command accepts a file name as
+argument, and causes this file to be the default for future @code{run}
+commands. It also resets the controlling terminal for the child
+process, for future @code{run} commands. For example,
-The symbol information for a symbol scope block has a start address
-smaller than the address of the preceding source line. This is known
-to occur in the SunOS 4.1.1 (and earlier) C compiler. _GDBN__ circumvents
-the problem by treating the symbol scope block as starting on the
-previous source line.
-
-@comment @item{encountered DBX-style class variable debugging information.
-@comment You seem to have compiled your program with "g++ -g0" instead of "g++ -g".
-@comment Therefore _GDBN__ will not know about your class variables}
-@comment
-@comment This error indicates that the symbol information produced for a C++
-@comment program includes zero-size fields, which indicated static fields in
-@comment a previous release of the G++ compiler. This message is probably
-@comment obsolete.
-@comment
-@item bad string table offset in symbol @var{n}
+@example
+tty /dev/ttyb
+@end example
-Symbol number @var{n} contains a pointer into the string table which is
-larger than the size of the string table. _GDBN__ circumvents the problem
-by considering the symbol to have the name @code{foo}, which may cause
-other problems if many symbols end up with this name. @cindex{foo}
+@noindent
+directs that processes started with subsequent @code{run} commands
+default to do input and output on the terminal @file{/dev/ttyb} and have
+that as their controlling terminal.
-@item unknown symbol type @code{0xNN}
+An explicit redirection in @code{run} overrides the @code{tty} command's
+effect on the input/output device, but not its effect on the controlling
+terminal.
-The symbol information contains new data types that _GDBN__ does not yet
-know how to read. @code{0xNN} is the symbol type of the misunderstood
-information, in hexadecimal. _GDBN__ circumvents the error by ignoring
-this symbol information. This will usually allow the program to be
-debugged, though certain symbols will not be accessible. If you
-encounter such a problem and feel like debugging it, you can debug _GDBP__
-with itself, breakpoint on "complain", then go "up" to
-read_dbx_symtab() and examine *bufp to see the symbol.
+When you use the @code{tty} command or redirect input in the @code{run}
+command, only the input @emph{for your program} is affected. The input
+for _GDBN__ still comes from your terminal.
-@c @item stub type has NULL name
-@c
-@c FIXME, Mike Tiemann needs to write about what this means.
+@node Attach, Kill Process, Input/Output, Running
+@section Debugging an Already-Running Process
+@kindex attach
+@cindex attach
-@item const/volatile indicator missing, got 'X'
+@table @code
+@item attach @var{process-id}
+This command
+attaches to a running process---one that was started outside _GDBN__.
+(@code{info files} will show your active targets.) The command takes as
+argument a process ID. The usual way to find out the process-id of
+a Unix process is with the @code{ps} utility, or with the @samp{jobs -l}
+shell command.
+
+@code{attach} will not repeat if you press @key{RET} a second time after
+executing the command.
+@end table
-The symbol information for a C++ type is missing some information that
-the compiler should have output for it.
+To use @code{attach}, you must be debugging in an environment which
+supports processes. You must also have permission to send the process a
+signal, and it must have the same effective user ID as the _GDBN__
+process.
-@item C++ type mismatch between compiler and debugger
+When using @code{attach}, you should first use the @code{file} command
+to specify the program running in the process and load its symbol table.
+@xref{Files, ,Commands to Specify Files}.
-The debugger could not parse a type specification output by the compiler
-for some C++ object.
+The first thing _GDBN__ does after arranging to debug the specified
+process is to stop it. You can examine and modify an attached process
+with all the _GDBN__ commands that are ordinarily available when you start
+processes with @code{run}. You can insert breakpoints; you can step and
+continue; you can modify storage. If you would rather the process
+continue running, you may use the @code{continue} command after
+attaching _GDBN__ to the process.
+@table @code
+@item detach
+@kindex detach
+When you have finished debugging the attached process, you can use the
+@code{detach} command to release it from _GDBN__'s control. Detaching
+the process continues its execution. After the @code{detach} command,
+that process and _GDBN__ become completely independent once more, and you
+are ready to @code{attach} another process or start one with @code{run}.
+@code{detach} will not repeat if you press @key{RET} again after
+executing the command.
@end table
-@item core-file @var{filename}
-@itemx core @var{filename}
-@kindex core
-@kindex core-file
-Specify the whereabouts of a core dump file to be used as the ``contents
-of memory''. Traditionally, core files contain only some parts of the
-address space of the process that generated them; _GDBN__ can access the
-executable file itself for other parts.
+If you exit _GDBN__ or use the @code{run} command while you have an attached
+process, you kill that process. By default, you will be asked for
+confirmation if you try to do either of these things; you can control
+whether or not you need to confirm by using the @code{set confirm} command
+(@pxref{Messages/Warnings, ,Optional Warnings and Messages}).
-@samp{core-file} with no argument specifies that no core file is
-to be used.
+@node Kill Process, Process Information, Attach, Running
+@c @group
+@section Killing the Child Process
-Note that the core file is ignored when your program is actually running
-under _GDBN__. So, if you have been running the program and you wish to
-debug a core file instead, you must kill the subprocess in which the
-program is running. To do this, use the @samp{kill} command
-(@pxref{Kill Process}).
+@table @code
+@item kill
+@kindex kill
+Kill the child process in which your program is running under _GDBN__.
+@end table
-@item load @var{filename}
-@kindex load
-This command will dynamically link @var{filename} on the current target,
-performing any necessary downloads, then add @var{filename}'s symbol
-table in the same way as the @samp{add-syms} command.
+This command is useful if you wish to debug a core dump instead of a
+running process. _GDBN__ ignores any core dump file while your program
+is running.
+@c @end group
-@item add-syms @var{filename} @var{address}
-@kindex add-syms
-@cindex dynamic linking
-The @samp{add-syms} command reads additional symbol table information
-from the file @var{filename}. You would use this command when that file
-has been dynamically loaded (by some other means) into the program that
-is running. @var{address} should be the memory address at which the
-file has been loaded; _GDBN__ cannot figure this out for itself.
+On some operating systems, a program cannot be executed outside _GDBN__
+while you have breakpoints set on it inside _GDBN__. You can use the
+@code{kill} command in this situation to permit running your program
+outside the debugger.
-The symbol table of the file @var{filename} is added to the symbol table
-originally read with the @samp{symbol-file} command. You can use the
-@samp{add-syms} command any number of times; the new symbol data thus
-read keeps adding to the old. The @samp{symbol-file} command forgets
-all the symbol data _GDBN__ has read.
+The @code{kill} command is also useful if you wish to recompile and
+relink your program, since on many systems it is impossible to modify an
+executable file while it is running in a process. In this case, when you
+next type @code{run}, _GDBN__ will notice that the file has changed, and
+will re-read the symbol table (while trying to preserve your current
+breakpoint settings).
-@item info files
-@itemx info target
-@kindex info files
-@kindex info target
-@samp{info files} and @samp{info target} are synonymous; both print the
-current targets (@pxref{Targets}), including the names of the
-executable and core dump files currently in use by _GDBN__, and the files
-from which symbols were loaded.
+@node Process Information, , Kill Process, Running
+@section Additional Process Information
-Beware: the similar command @samp{info targets} lists all possible
-targets rather than current ones.
+@kindex /proc
+@cindex process image
+Some operating systems provide a facility called @samp{/proc} that can
+be used to examine the image of a running process using file-system
+subroutines. If _GDBN__ is configured for an operating system with this
+facility, the command @code{info proc} is available to report on several
+kinds of information about the process running your program.
+@table @code
+@item info proc
+@kindex info proc
+Summarize available information about the process.
+
+@item info proc mappings
+@kindex info proc mappings
+Report on the address ranges accessible in the program, with information
+on whether your program may read, write, or execute each range.
+
+@item info proc times
+@kindex info proc times
+Starting time, user CPU time, and system CPU time for your program and
+its children.
+
+@item info proc id
+@kindex info proc id
+Report on the process ID's related to your program: its own process id,
+the id of its parent, the process group id, and the session id.
+
+@item info proc status
+@kindex info proc status
+General information on the state of the process. If the process is
+stopped, this report includes the reason for stopping, and any signal
+received.
+
+@item info proc all
+Show all the above information about the process.
@end table
-While all three file-specifying commands allow both absolute and relative
-file names as arguments, _GDBN__ always converts the file name to an absolute
-one and remembers it that way.
+@node Stopping, Stack, Running, Top
+@chapter Stopping and Continuing
-@kindex sharedlibrary
-@kindex share
-@cindex shared libraries
+The principal purpose of using a debugger is so that you can stop your
+program before it terminates; or so that, if your program runs into
+trouble, you can investigate and find out why.
-_GDBN__ supports the SunOS shared library format. Symbols from a shared
-library cannot be referenced before the shared library has been linked
-with the program. (That is to say, after one types @samp{run} and
-the function @code{main()} has been entered; or when examining core
-files.) Once the shared library has been linked in, you can use the
-following commands:
+Inside _GDBN__, your program may stop for any of several reasons, such
+as a signal, a breakpoint, or reaching a new line after a _GDBN__
+command such as @code{step}. You may then examine and change
+variables, set new breakpoints or remove old ones, and then continue
+execution. Usually, the messages shown by _GDBN__ provide ample
+explanation of the status of your program---but you can also explicitly
+request this information at any time.
@table @code
-@item sharedlibrary @var{regex}
-@itemx share @var{regex}
-Load shared object library symbols for files matching a UNIX regular
-expression.
-
-@item share
-@itemx sharedlibrary
-Load symbols for all shared libraries.
-
-@item info share
-@itemx info sharedlibrary
-@kindex info sharedlibrary
-@kindex info share
-Print the names of the shared libraries which are currently loaded.
+@item info program
+@kindex info program
+Display information about the status of your program: whether it is
+running or not, what process it is, and why it stopped.
@end table
+@menu
+* Breakpoints:: Breakpoints, Watchpoints, and Exceptions
+* Continuing and Stepping:: Resuming Execution
+* Signals:: Signals
+@end menu
-@node Compilation, Targets, Files, Top
-@chapter Compiling for Debugging
-
-In order to debug a program effectively, you need to ask for debugging
-information when you compile it. This debugging information is stored
-in the object file; it describes the data type of each variable or
-function and the correspondence between source line numbers and
-addresses in the executable code.
-
-To request debugging information, specify the @samp{-g} option when you run
-the compiler.
+@node Breakpoints, Continuing and Stepping, Stopping, Stopping
+@section Breakpoints, Watchpoints, and Exceptions
-The Unix C compiler is unable to handle the @samp{-g} and @samp{-O} options
-together. This means that you cannot ask for optimization if you ask for
-debugger information.
+@cindex breakpoints
+A @dfn{breakpoint} makes your program stop whenever a certain point in
+the program is reached. For each breakpoint, you can add various
+conditions to control in finer detail whether your program will stop.
+You can set breakpoints with the @code{break} command and its variants
+(@pxref{Set Breaks, ,Setting Breakpoints}), to specify the place where
+your program should stop by line number, function name or exact address
+in the program. In languages with exception handling (such as GNU
+C++), you can also set breakpoints where an exception is raised
+(@pxref{Exception Handling, ,Breakpoints and Exceptions}).
-The GNU C compiler supports @samp{-g} with or without @samp{-O}, making it
-possible to debug optimized code. We recommend that you @emph{always} use
-@samp{-g} whenever you compile a program. You may think the program is
-correct, but there's no sense in pushing your luck.
+@cindex watchpoints
+@cindex memory tracing
+@cindex breakpoint on memory address
+@cindex breakpoint on variable modification
+A @dfn{watchpoint} is a special breakpoint that stops your program
+when the value of an expression changes. You must use a different
+command to set watchpoints (@pxref{Set Watchpoints, ,Setting
+Watchpoints}), but aside from that, you can manage a watchpoint like
+any other breakpoint: you enable, disable, and delete both breakpoints
+and watchpoints using the same commands.
+
+@cindex breakpoint numbers
+@cindex numbers for breakpoints
+_GDBN__ assigns a number to each breakpoint or watchpoint when you
+create it; these numbers are successive integers starting with one. In
+many of the commands for controlling various features of breakpoints you
+use the breakpoint number to say which breakpoint you want to change.
+Each breakpoint may be @dfn{enabled} or @dfn{disabled}; if disabled, it has
+no effect on your program until you enable it again.
-Some things do not work as well with @samp{-g -O} as with just
-@samp{-g}, particularly on machines with instruction scheduling. If in
-doubt, recompile with @samp{-g} alone, and if this fixes the problem,
-please report it as a bug (including a test case---@pxref{_GDBN__ Bugs}).
+@menu
+* Set Breaks:: Setting Breakpoints
+* Set Watchpoints:: Setting Watchpoints
+* Exception Handling:: Breakpoints and Exceptions
+* Delete Breaks:: Deleting Breakpoints
+* Disabling:: Disabling Breakpoints
+* Conditions:: Break Conditions
+* Break Commands:: Breakpoint Command Lists
+* Breakpoint Menus:: Breakpoint Menus
+* Error in Breakpoints::
+@end menu
-Older versions of the GNU C compiler, _GCC__, permitted a variant option
-@samp{-gg} for debugging information. _GDBN__ no longer supports this format;
-if your GNU C compiler has this option, do not use it.
+@node Set Breaks, Set Watchpoints, Breakpoints, Breakpoints
+@subsection Setting Breakpoints
-@ignore
-@comment As far as I know, there are no cases in which _GDBN__ will
-@comment produce strange output in this case. (but no promises).
-If your program includes archives made with the @code{ar} program, and
-if the object files used as input to @code{ar} were compiled without the
-@samp{-g} option and have names longer than 15 characters, _GDBN__ will get
-confused reading the program's symbol table. No error message will be
-given, but _GDBN__ may behave strangely. The reason for this problem is a
-deficiency in the Unix archive file format, which cannot represent file
-names longer than 15 characters.
+@c FIXME LMB what does GDB do if no code on line of breakpt?
+@c consider in particular declaration with/without initialization.
+@c
+@c FIXME 2 is there stuff on this already? break at fun start, already init?
-To avoid this problem, compile the archive members with the @samp{-g}
-option or use shorter file names. Alternatively, use a version of GNU
-@code{ar} dated more recently than August 1989.
-@end ignore
+@kindex break
+@kindex b
+@kindex $bpnum
+@cindex latest breakpoint
+Breakpoints are set with the @code{break} command (abbreviated
+@code{b}). The debugger convenience variable @samp{$bpnum} records the
+number of the beakpoint you've set most recently; see @ref{Convenience
+Vars,, Convenience Variables}, for a discussion of what you can do with
+convenience variables.
-@node Targets, Running, Compilation, Top
-@chapter Specifying a Debugging Target
-@cindex debugging target
-@kindex target
-A @dfn{target} is an interface between the debugger and a particular
-kind of file or process.
+You have several ways to say where the breakpoint should go.
-Often, you will be able to run _GDBN__ in the same host environment as the
-program you are debugging; in that case, the debugging target can just be
-specified as a side effect of the @samp{file} or @samp{core} commands.
-When you need more flexibility---for example, running _GDBN__ on a
-physically separate host, controlling standalone systems over a
-serial port, or realtime systems over a TCP/IP connection---you can use
-the @samp{target} command.
+@table @code
+@item break @var{function}
+Set a breakpoint at entry to function @var{function}. When using source
+languages that permit overloading of symbols, such as C++,
+@var{function} may refer to more than one possible place to break.
+@xref{Breakpoint Menus}, for a discussion of that situation.
-@menu
-* Active Targets:: Active Targets
-* Target Commands:: Commands for Managing Targets
-@end menu
+@item break +@var{offset}
+@itemx break -@var{offset}
+Set a breakpoint some number of lines forward or back from the position
+at which execution stopped in the currently selected frame.
-@node Active Targets, Target Commands, Targets, Targets
-@section Active Targets
-@cindex stacking targets
-@cindex active targets
-@cindex multiple targets
+@item break @var{linenum}
+Set a breakpoint at line @var{linenum} in the current source file.
+That file is the last file whose source text was printed. This
+breakpoint will stop your program just before it executes any of the
+code on that line.
-Targets are managed in three @dfn{strata} that correspond to different
-classes of target: processes, core files, and executable files. This
-allows you to (for example) start a process and inspect its activity
-without abandoning your work on a core file.
+@item break @var{filename}:@var{linenum}
+Set a breakpoint at line @var{linenum} in source file @var{filename}.
-More than one target can potentially respond to a request. In
-particular, when you access memory _GDBN__ will walk down the three strata of
-targets until it finds a target that can handle that particular address.
+@item break @var{filename}:@var{function}
+Set a breakpoint at entry to function @var{function} found in file
+@var{filename}. Specifying a file name as well as a function name is
+superfluous except when multiple files contain similarly named
+functions.
-Strata are always examined in a fixed order: first a process if there is
-one, then a core file if there is one, and finally an executable file if
-there is one of those.
+@item break *@var{address}
+Set a breakpoint at address @var{address}. You can use this to set
+breakpoints in parts of your program which do not have debugging
+information or source files.
-When you specify a new target in a given stratum, it replaces any target
-previously in that stratum.
+@item break
+When called without any arguments, @code{break} sets a breakpoint at
+the next instruction to be executed in the selected stack frame
+(@pxref{Stack, ,Examining the Stack}). In any selected frame but the
+innermost, this will cause your program to stop as soon as control
+returns to that frame. This is similar to the effect of a
+@code{finish} command in the frame inside the selected frame---except
+that @code{finish} does not leave an active breakpoint. If you use
+@code{break} without an argument in the innermost frame, _GDBN__ will stop
+the next time it reaches the current location; this may be useful
+inside loops.
-To get rid of a target without replacing it, use the @samp{detach}
-command. The related command @samp{attach} provides you with a way of
-choosing a particular running process as a new target. @xref{Attach}.
+_GDBN__ normally ignores breakpoints when it resumes execution, until at
+least one instruction has been executed. If it did not do this, you
+would be unable to proceed past a breakpoint without first disabling the
+breakpoint. This rule applies whether or not the breakpoint already
+existed when your program stopped.
-@node Target Commands, , Active Targets, Targets
-@section Commands for Managing Targets
+@item break @dots{} if @var{cond}
+Set a breakpoint with condition @var{cond}; evaluate the expression
+@var{cond} each time the breakpoint is reached, and stop only if the
+value is nonzero---that is, if @var{cond} evaluates as true.
+@samp{@dots{}} stands for one of the possible arguments described
+above (or no argument) specifying where to break. @xref{Conditions,
+,Break Conditions}, for more information on breakpoint conditions.
-@table @code
-@item target @var{type} @var{parameters}
-Connects the _GDBN__ host environment to a target machine or process. A
-target is typically a protocol for talking to debugging facilities. You
-use the argument @var{type} to specify the type or protocol of the
-target machine; for example, @samp{target vxworks} for a TCP/IP link to
-a VxWorks system.
+@item tbreak @var{args}
+@kindex tbreak
+Set a breakpoint enabled only for one stop. @var{args} are the
+same as for the @code{break} command, and the breakpoint is set in the same
+way, but the breakpoint is automatically disabled after the first time your
+program stops there. @xref{Disabling, ,Disabling Breakpoints}.
-Further @var{parameters} are interpreted by the target protocol, but
-typically include things like device names or host names to connect
-with, process numbers, and baud rates. Executing
-@example
- target @var{type}
-@end example
+@item rbreak @var{regex}
+@kindex rbreak
+@cindex regular expression
+@c FIXME what kind of regexp?
+Set breakpoints on all functions matching the regular expression
+@var{regex}. This command
+sets an unconditional breakpoint on all matches, printing a list of all
+breakpoints it set. Once these breakpoints are set, they are treated
+just like the breakpoints set with the @code{break} command. They can
+be deleted, disabled, made conditional, etc., in the standard ways.
+
+When debugging C++ programs, @code{rbreak} is useful for setting
+breakpoints on overloaded functions that are not members of any special
+classes.
+
+@kindex info breakpoints
+@cindex @code{$_} and @code{info breakpoints}
+@item info breakpoints @r{[}@var{n}@r{]}
+@itemx info break @r{[}@var{n}@r{]}
+@itemx info watchpoints @r{[}@var{n}@r{]}
+Print a table of all breakpoints and watchpoints set and not
+deleted, with the following columns for each breakpoint:
+
+@table @emph
+@item Breakpoint Numbers
+@item Type
+Breakpoint or watchpoint.
+@item Disposition
+Whether the breakpoint is marked to be disabled or deleted when hit.
+@item Enabled or Disabled
+Enabled breakpoints are marked with @samp{y}. @samp{n} marks breakpoints
+that are not enabled.
+@item Address
+Where the breakpoint is in your program, as a memory address
+@item What
+Where the breakpoint is in the source for your program, as a file and
+line number.
+@end table
@noindent
-(without any parameters) will issue a message about what
-parameters are required for that target type.
+Breakpoint commands, if any, are listed after the line for the
+corresponding breakpoint.
-@item info targets
-@kindex info targets
-Displays the names of all targets available. Beware: the similar
-command @samp{info target} displays targets currently in use rather than
-all available ones. @samp{info files} gives the same information as
-@samp{info target} (@pxref{Files}).
+@noindent
+@code{info break} with a breakpoint
+number @var{n} as argument lists only that breakpoint. The
+convenience variable @code{$_} and the default examining-address for
+the @code{x} command are set to the address of the last breakpoint
+listed (@pxref{Memory, ,Examining Memory}).
@end table
-Here are some common targets (available, or not, depending on _GDBN__
-configuration):
+_GDBN__ allows you to set any number of breakpoints at the same place in
+your program. There is nothing silly or meaningless about this. When
+the breakpoints are conditional, this is even useful
+(@pxref{Conditions, ,Break Conditions}).
+
+@cindex negative breakpoint numbers
+@cindex internal _GDBN__ breakpoints
+_GDBN__ itself sometimes sets breakpoints in your program for special
+purposes, such as proper handling of @code{longjmp} (in C programs).
+These internal breakpoints are assigned negative numbers, starting with
+@code{-1}; @samp{info breakpoints} does not display them, but the
+similar command @samp{info all-breakpoints} does.
@table @code
-@item target exec @var{prog}
-@kindex target exec
-An executable file. @samp{target exec @var{prog}} is the same as
-@samp{exec-file @var{prog}}.
+@kindex all-breakpoints
+@item info all-breakpoints
+Using the same format as @samp{info breakpoints}, display both the
+breakpoints you've set explicitly, and those _GDBN__ is using for
+internal purposes. Internal breakpoints are shown with negative
+breakpoint numbers. The type column identifies what kind of breakpoint
+is shown:
-@item target core @var{filename}
-@kindex target core
-A core dump file. @samp{target core @var{filename}} is the same as
-@samp{core-file @var{filename}}.
+@table @code
+@item breakpoint
+Normal, explicitly set breakpoint.
-@item target remote @var{dev}
-@kindex target remote
-Remote serial target in _GDBP__-specific protocol. The argument @var{dev}
-specifies what serial device to use for the connection (e.g.
-@code{/dev/ttya}).
+@item watchpoint
+Normal, explicitly set watchpoint.
-_if__(_AMD29K__)
-@item target amd-eb @var{dev} @var{speed} @var{PROG}
-@kindex target amd-eb
-@cindex AMD EB29K
-Remote PC-resident AMD EB29K board, attached over serial lines.
-@var{dev} is the serial device, as for @samp{target remote};
-@samp{speed} allows you to specify the linespeed; and @var{PROG} is the
-name of the program to be debugged, as it appears to DOS on the PC.
-@xref{AMD29K Remote}.
+@item longjmp
+Internal breakpoint, used to handle correctly stepping through
+@code{longjmp} calls.
-_fi__(_AMD29K__)
-_if__(_I960__)
-@item target nindy @var{devicename}
-@kindex target nindy
-An Intel 960 board controlled by a Nindy Monitor. @var{devicename} is
-the name of the serial device to use for the connection, e.g.
-@samp{/dev/ttya}.
+@item longjmp resume
+Internal breakpoint at the target of a @code{longjmp}.
-_fi__(_I960__)
-_if__(_VXWORKS__)
-@item target vxworks @var{machinename}
-@kindex target vxworks
-A VxWorks system, attached via TCP/IP. The argument @var{machinename}
-is the target system's machine name or IP address.
+@item until
+Temporary internal breakpoint used by the _GDBN__ @code{until} command.
-_fi__(_VXWORKS__)
+@item finish
+Temporary internal breakpoint used by the _GDBN__ @code{finish} command.
@end table
-_if__(_GENERIC__)
-Different targets are available on different configurations of _GDBN__; your
-configuration may have more or fewer targets.
-_fi__(_GENERIC__)
-
-@node Running, Stopping, Targets, Top
-@chapter Running Programs Under _GDBN__
-
-@cindex running
-@kindex run
-To start your program under _GDBN__, use the @samp{run} command. Except on
-VxWorks, the program must already have been specified using the
-@samp{file} or @samp{exec-file} command, or with an argument to _GDBN__
-(@pxref{Files}).
-
-On targets that support processes, @samp{run} creates an inferior
-process and makes that process run your program. On other targets,
-@samp{run} jumps to the location it has recorded for the start of the
-program.
-
-The execution of a program is affected by certain information it
-receives from its superior. _GDBN__ provides ways to specify this
-information, which you must do @i{before} starting the program. (You
-can change it after starting the program, but such changes do not affect
-the program unless you start it over again.) This information may be
-divided into three categories:
-
-@table @asis
-@item The @i{arguments.}
-You specify the arguments to give the program as the arguments of the
-@samp{run} command. If a shell is available on your target, the shell
-is used to pass the arguments, so that you may use normal conventions
-(for example regular expression expansion or variable substitution) in
-describing the arguments. In Unix systems, you can control which shell
-is used with the @code{SHELL} environment variable.
-
-@item The @i{environment.}
-The program normally inherits its environment from _GDBN__, but you can
-use the _GDBN__ commands @samp{set environment} and
-@samp{unset environment} to change parts of the environment that will
-be given to the program.@refill
-
-@item The @i{working directory.}
-The program inherits its working directory from _GDBN__. You can set _GDBN__'s
-working directory with the @samp{cd} command in _GDBN__.
@end table
-When you issue the @samp{run} command, your program begins to execute
-immediately. @xref{Stopping}, for discussion of how to arrange for your
-program to stop.
-
-Note that once your program has been started by the @samp{run} command,
-you may evaluate expressions that involve calls to functions in the
-inferior, using the @samp{print} or @samp{call} commands. @xref{Data}.
-If the modification time of your symbol file has changed since the last
-time _GDBN__ read its symbols, _GDBN__ will discard its symbol table and re-read
-it. In this process, it tries to retain your current breakpoints.
+@node Set Watchpoints, Exception Handling, Set Breaks, Breakpoints
+@subsection Setting Watchpoints
+@cindex setting watchpoints
-@menu
-* Arguments:: Specifying the arguments for your program.
-* Environment:: Specifying the environment for your program.
-* Working Directory:: Specifying the working directory for giving
- to your program when it is run.
-* Input/Output:: Specifying the program's standard input and output.
-* Attach:: Debugging a process started outside _GDBN__.
-* Kill Process:: Getting rid of the child process running your program.
-@end menu
-
-@node Arguments, Environment, Running, Running
-@section Your Program's Arguments
+You can use a watchpoint to stop execution whenever the value of an
+expression changes, without having to predict a particular place
+where this may happen.
-@cindex arguments (to your program)
-The arguments to your program are specified by the arguments of the
-@samp{run} command. They are passed to a shell, which expands wildcard
-characters and performs redirection of I/O, and thence to the program.
-
-@samp{run} with no arguments uses the same arguments used by the previous
-@samp{run}.
+Watchpoints currently execute two orders of magnitude more slowly than
+other breakpoints, but this can well be worth it to catch errors where
+you have no clue what part of your program is the culprit. Some
+processors provide special hardware to support watchpoint evaluation; future
+releases of _GDBN__ will use such hardware if it is available.
-@kindex set args
@table @code
-@item set args
-The command @samp{set args} can be used to specify the arguments to be used
-the next time the program is run. If @samp{set args} has no arguments, it
-means to use no arguments the next time the program is run. If you have
-run your program with arguments and want to run it again with no arguments,
-this is the only way to do so.
+@kindex watch
+@item watch @var{expr}
+Set a watchpoint for an expression.
-@item show args
-@kindex show args
-Show the arguments to give your program when it is started.
+@kindex info watchpoints
+@item info watchpoints
+This command prints a list of watchpoints and breakpoints; it is the
+same as @code{info break}.
@end table
-@node Environment, Working Directory, Arguments, Running
-@section Your Program's Environment
+@node Exception Handling, Delete Breaks, Set Watchpoints, Breakpoints
+@subsection Breakpoints and Exceptions
+@cindex exception handlers
-@cindex environment (of your program)
-The @dfn{environment} consists of a set of @dfn{environment variables} and
-their values. Environment variables conventionally record such things as
-your user name, your home directory, your terminal type, and your search
-path for programs to run. Usually you set up environment variables with
-the shell and they are inherited by all the other programs you run. When
-debugging, it can be useful to try running the program with different
-environments without having to start the debugger over again.
+Some languages, such as GNU C++, implement exception handling. You can
+use _GDBN__ to examine what caused your program to raise an exception,
+and to list the exceptions your program is prepared to handle at a
+given point in time.
@table @code
-@item show environment @var{varname}
-@kindex show environment
-Print the value of environment variable @var{varname} to be given to
-your program when it is started.
+@item catch @var{exceptions}
+@kindex catch
+You can set breakpoints at active exception handlers by using the
+@code{catch} command. @var{exceptions} is a list of names of exceptions
+to catch.
+@end table
-@item show environment
-Print the names and values of all environment variables to be given to
-your program when it is started.
+You can use @code{info catch} to list active exception handlers.
+@xref{Frame Info, ,Information About a Frame}.
-@item set environment @var{varname} @var{value}
-@itemx set environment @var{varname} = @var{value}
-@kindex set environment
-Sets environment variable @var{varname} to @var{value}, for your program
-only, not for _GDBN__ itself. @var{value} may be any string; the values of
-environment variables are just strings, and any interpretation is
-supplied by your program itself. The @var{value} parameter is optional;
-if it is eliminated, the variable is set to a null value.
+There are currently some limitations to exception handling in _GDBN__.
+These will be corrected in a future release.
-For example, this command:
+@itemize @bullet
+@item
+If you call a function interactively, _GDBN__ normally returns
+control to you when the function has finished executing. If the call
+raises an exception, however, the call may bypass the mechanism that
+returns control to you and cause your program to simply continue
+running until it hits a breakpoint, catches a signal that _GDBN__ is
+listening for, or exits.
+@item
+You cannot raise an exception interactively.
+@item
+You cannot interactively install an exception handler.
+@end itemize
+
+@cindex raise exceptions
+Sometimes @code{catch} is not the best way to debug exception handling:
+if you need to know exactly where an exception is raised, it is better to
+stop @emph{before} the exception handler is called, since that way you
+can see the stack before any unwinding takes place. If you set a
+breakpoint in an exception handler instead, it may not be easy to find
+out where the exception was raised.
+
+To stop just before an exception handler is called, you need some
+knowledge of the implementation. In the case of GNU C++, exceptions are
+raised by calling a library function named @code{__raise_exception}
+which has the following ANSI C interface:
@example
-set env USER = foo
+ /* @var{addr} is where the exception identifier is stored.
+ ID is the exception identifier. */
+ void __raise_exception (void **@var{addr}, void *@var{id});
@end example
@noindent
-tells the program, when subsequently run, to assume it is being run
-on behalf of the user named @samp{foo}.
+To make the debugger catch all exceptions before any stack
+unwinding takes place, set a breakpoint on @code{__raise_exception}
+(@pxref{Breakpoints, ,Breakpoints Watchpoints and Exceptions}).
-@item delete environment @var{varname}
-@itemx unset environment @var{varname}
-@kindex delete environment
-@kindex unset environment
-Remove variable @var{varname} from the environment to be passed to your
-program. This is different from @samp{set env @var{varname}@ =};
-@samp{delete environment} removes the variable from the environment,
-rather than assigning it an empty value. This command can be
-abbreviated @samp{d e}.
-@end table
+With a conditional breakpoint (@pxref{Conditions, ,Break Conditions})
+that depends on the value of @var{id}, you can stop your program when
+a specific exception is raised. You can use multiple conditional
+breakpoints to stop your program when any of a number of exceptions are
+raised.
-@node Working Directory, Input/Output, Environment, Running
-@section Your Program's Working Directory
+@node Delete Breaks, Disabling, Exception Handling, Breakpoints
+@subsection Deleting Breakpoints
-@cindex working directory (of your program)
-Each time you start your program with @samp{run}, it inherits its
-working directory from the current working directory of _GDBN__. _GDBN__'s
-working directory is initially whatever it inherited from its parent
-process (typically the shell), but you can specify a new working
-directory in _GDBN__ with the @samp{cd} command.
+@cindex clearing breakpoints, watchpoints
+@cindex deleting breakpoints, watchpoints
+It is often necessary to eliminate a breakpoint or watchpoint once it
+has done its job and you no longer want your program to stop there. This
+is called @dfn{deleting} the breakpoint. A breakpoint that has been
+deleted no longer exists; it is forgotten.
-The _GDBN__ working directory also serves as a default for the commands
-that specify files for _GDBN__ to operate on. @xref{Files}.
+With the @code{clear} command you can delete breakpoints according to
+where they are in your program. With the @code{delete} command you can
+delete individual breakpoints or watchpoints by specifying their
+breakpoint numbers.
+
+It is not necessary to delete a breakpoint to proceed past it. _GDBN__
+automatically ignores breakpoints on the first instruction to be executed
+when you continue execution without changing the execution address.
@table @code
-@item cd @var{directory}
-@kindex cd
-Set _GDBN__'s working directory to @var{directory}.
+@item clear
+@kindex clear
+Delete any breakpoints at the next instruction to be executed in the
+selected stack frame (@pxref{Selection, ,Selecting a Frame}). When
+the innermost frame is selected, this is a good way to delete a
+breakpoint where your program just stopped.
-@item pwd
-@kindex pwd
-Print _GDBN__'s working directory.
-@end table
+@item clear @var{function}
+@itemx clear @var{filename}:@var{function}
+Delete any breakpoints set at entry to the function @var{function}.
-@node Input/Output, Attach, Working Directory, Running
-@section Your Program's Input and Output
+@item clear @var{linenum}
+@itemx clear @var{filename}:@var{linenum}
+Delete any breakpoints set at or within the code of the specified line.
-@cindex redirection
-@cindex i/o
-@cindex terminal
-@cindex controlling terminal
-By default, the program you run under _GDBN__ does input and output to the same
-terminal that _GDBN__ uses.
+@item delete @r{[}breakpoints@r{]} @r{[}@var{bnums}@dots{}@r{]}
+@cindex delete breakpoints
+@kindex delete
+@kindex d
+Delete the breakpoints or watchpoints of the numbers specified as
+arguments. If no argument is specified, delete all breakpoints (_GDBN__
+asks confirmation, unless you have @code{set confirm off}). You
+can abbreviate this command as @code{d}.
+@end table
-You can redirect the program's input and/or output using @samp{sh}-style
-redirection commands in the @samp{run} command. For example,
+@node Disabling, Conditions, Delete Breaks, Breakpoints
+@subsection Disabling Breakpoints
-@example
-run > outfile
-@end example
+@cindex disabled breakpoints
+@cindex enabled breakpoints
+Rather than deleting a breakpoint or watchpoint, you might prefer to
+@dfn{disable} it. This makes the breakpoint inoperative as if it had
+been deleted, but remembers the information on the breakpoint so that
+you can @dfn{enable} it again later.
-@noindent
-starts the program, diverting its output to the file @file{outfile}.
+You disable and enable breakpoints and watchpoints with the
+@code{enable} and @code{disable} commands, optionally specifying one or
+more breakpoint numbers as arguments. Use @code{info break} or
+@code{info watch} to print a list of breakpoints or watchpoints if you
+do not know which numbers to use.
-@kindex tty
-Another way to specify where the program should do input and output is
-with the @samp{tty} command. This command accepts a file name as
-argument, and causes this file to be the default for future @samp{run}
-commands. It also resets the controlling terminal for the child
-process, for future @samp{run} commands. For example,
+A breakpoint or watchpoint can have any of four different states of
+enablement:
-@example
-tty /dev/ttyb
-@end example
+@itemize @bullet
+@item
+Enabled. The breakpoint will stop your program. A breakpoint set
+with the @code{break} command starts out in this state.
+@item
+Disabled. The breakpoint has no effect on your program.
+@item
+Enabled once. The breakpoint will stop your program, but
+when it does so it will become disabled. A breakpoint set
+with the @code{tbreak} command starts out in this state.
+@item
+Enabled for deletion. The breakpoint will stop your program, but
+immediately after it does so it will be deleted permanently.
+@end itemize
-@noindent
-directs that processes started with subsequent @samp{run} commands
-default to do input and output on the terminal @file{/dev/ttyb} and have
-that as their controlling terminal.
+You can use the following commands to enable or disable breakpoints and
+watchpoints:
-An explicit redirection in @samp{run} overrides the @samp{tty} command's
-effect on input/output redirection, but not its effect on the
-controlling terminal.
+@table @code
+@item disable @r{[}breakpoints@r{]} @r{[}@var{bnums}@dots{}@r{]}
+@kindex disable breakpoints
+@kindex disable
+@kindex dis
+Disable the specified breakpoints---or all breakpoints, if none are
+listed. A disabled breakpoint has no effect but is not forgotten. All
+options such as ignore-counts, conditions and commands are remembered in
+case the breakpoint is enabled again later. You may abbreviate
+@code{disable} as @code{dis}.
-When you use the @samp{tty} command or redirect input in the @samp{run}
-command, only the @emph{input for your program} is affected. The input
-for _GDBN__ still comes from your terminal.
+@item enable @r{[}breakpoints@r{]} @r{[}@var{bnums}@dots{}@r{]}
+@kindex enable breakpoints
+@kindex enable
+Enable the specified breakpoints (or all defined breakpoints). They
+become effective once again in stopping your program.
-@node Attach, Kill Process, Input/Output, Running
-@section Debugging an Already-Running Process
-@kindex attach
-@cindex attach
+@item enable @r{[}breakpoints@r{]} once @var{bnums}@dots{}
+Enable the specified breakpoints temporarily. Each will be disabled
+again the next time it stops your program.
-@table @code
-@item attach @var{process--id}
-This command attaches to a running process, if your currently selected
-target supports processes. (@samp{info files} will show your active
-targets). The command takes as argument a process ID.
-
-You specify a process ID to debug an already-running process that was
-started outside of _GDBN__. (The usual way to find out the process-id of
-a Unix process is with the @code{ps} utility, or with the @code{jobs -l}
-shell command.) In this case, you must have permission to send the
-process a signal, and it must have the same effective user ID as the
-debugger.
+@item enable @r{[}breakpoints@r{]} delete @var{bnums}@dots{}
+Enable the specified breakpoints to work once and then die. Each of
+the breakpoints will be deleted the next time it stops your program.
@end table
-When using @samp{attach}, you should first use the @samp{file} command
-to specify the program running in the process and load its symbol table.
+Save for a breakpoint set with @code{tbreak} (@pxref{Set Breaks,
+,Setting Breakpoints}), breakpoints that you set are initially
+enabled; subsequently, they become disabled or enabled only when you
+use one of the commands above. (The command @code{until} can set and
+delete a breakpoint of its own, but it will not change the state of
+your other breakpoints; see @ref{Continuing and Stepping, ,Continuing and Stepping}.)
-The first thing _GDBN__ does after arranging to debug the process is to stop
-it. You can examine and modify an attached process with all the _GDBN__
-commands that ordinarily available when you start processes with
-@samp{run}. You can insert breakpoints; you can step and continue; you
-can modify storage. If you would rather the process continue running,
-you may use the @samp{continue} command after attaching _GDBN__ to the
-process.
+@node Conditions, Break Commands, Disabling, Breakpoints
+@subsection Break Conditions
+@cindex conditional breakpoints
+@cindex breakpoint conditions
-@kindex detach
-When you have finished debugging the attached process, you can use the
-@samp{detach} command to release it from _GDBN__'s control. Detaching
-the process continues its execution. After the @samp{detach} command,
-that process and _GDBN__ become completely independent once more, and you
-are ready to @samp{attach} another process or start one with @samp{run}.
+@c FIXME what is scope of break condition expr? Context where wanted?
+@c in particular for a watchpoint?
+The simplest sort of breakpoint breaks every time your program reaches a
+specified place. You can also specify a @dfn{condition} for a
+breakpoint. A condition is just a Boolean expression in your
+programming language (@pxref{Expressions, ,Expressions}). A breakpoint with
+a condition evaluates the expression each time your program reaches it,
+and your program stops only if the condition is @emph{true}.
+
+This is the converse of using assertions for program validation; in that
+situation, you want to stop when the assertion is violated---that is,
+when the condition is false. In C, if you want to test an assertion expressed
+by the condition @var{assert}, you should set the condition
+@samp{! @var{assert}} on the appropriate breakpoint.
+
+Conditions are also accepted for watchpoints; you may not need them,
+since a watchpoint is inspecting the value of an expression anyhow---but
+it might be simpler, say, to just set a watchpoint on a variable name,
+and specify a condition that tests whether the new value is an interesting
+one.
-If you exit _GDBN__ or use the @samp{run} command while you have an attached
-process, you kill that process. By default, you will be asked for
-confirmation if you try to do either of these things; you can control
-whether or not this happens by using the @samp{set caution} command
-(@pxref{User Interface}).
+Break conditions can have side effects, and may even call functions in
+your program. This can be useful, for example, to activate functions
+that log program progress, or to use your own print functions to
+format special data structures. The effects are completely predictable
+unless there is another enabled breakpoint at the same address. (In
+that case, _GDBN__ might see the other breakpoint first and stop your
+program without checking the condition of this one.) Note that
+breakpoint commands are usually more convenient and flexible for the
+purpose of performing side effects when a breakpoint is reached
+(@pxref{Break Commands, ,Breakpoint Command Lists}).
-@node Kill Process, , Attach, Running
-@section Killing the Child Process
+Break conditions can be specified when a breakpoint is set, by using
+@samp{if} in the arguments to the @code{break} command. @xref{Set
+Breaks, ,Setting Breakpoints}. They can also be changed at any time
+with the @code{condition} command. The @code{watch} command does not
+recognize the @code{if} keyword; @code{condition} is the only way to
+impose a further condition on a watchpoint.
@table @code
-@item kill
-@kindex kill
-Kill the child process in which your program is running under _GDBN__.
-@end table
+@item condition @var{bnum} @var{expression}
+@kindex condition
+Specify @var{expression} as the break condition for breakpoint or
+watchpoint number @var{bnum}. From now on, this breakpoint will stop
+your program only if the value of @var{expression} is true (nonzero, in
+C). When you use @code{condition}, _GDBN__ checks @var{expression}
+immediately for syntactic correctness, and to determine whether symbols
+in it have referents in the context of your breakpoint.
+@c FIXME so what does GDB do if there is no referent? Moreover, what
+@c about watchpoints?
+_GDBN__ does
+not actually evaluate @var{expression} at the time the @code{condition}
+command is given, however. @xref{Expressions, ,Expressions}.
-This command is useful if you wish to debug a core dump instead. _GDBN__
-ignores any core dump file if it is actually running the program.
+@item condition @var{bnum}
+Remove the condition from breakpoint number @var{bnum}. It becomes
+an ordinary unconditional breakpoint.
+@end table
-On some operating systems, you can't execute your program in another
-process while breakpoints are active inside _GDBN__. The @samp{kill}
-command is also useful in this situation, if you wish to run the program
-outside the debugger.
+@cindex ignore count (of breakpoint)
+A special case of a breakpoint condition is to stop only when the
+breakpoint has been reached a certain number of times. This is so
+useful that there is a special way to do it, using the @dfn{ignore
+count} of the breakpoint. Every breakpoint has an ignore count, which
+is an integer. Most of the time, the ignore count is zero, and
+therefore has no effect. But if your program reaches a breakpoint whose
+ignore count is positive, then instead of stopping, it just decrements
+the ignore count by one and continues. As a result, if the ignore count
+value is @var{n}, the breakpoint will not stop the next @var{n} times it
+is reached.
-The @samp{kill} command is also useful if you wish to recompile and
-relink the program, since on many systems it is impossible to modify an
-executable file which is running in a process. In this case, when you
-next type @samp{run}, _GDBN__ will notice that the file has changed, and
-will re-read the symbol table (while trying to preserve your current
-breakpoint settings).
+@table @code
+@item ignore @var{bnum} @var{count}
+@kindex ignore
+Set the ignore count of breakpoint number @var{bnum} to @var{count}.
+The next @var{count} times the breakpoint is reached, your program's
+execution will not stop; other than to decrement the ignore count, _GDBN__
+takes no action.
-@node Stopping, Stack, Running, Top
-@chapter Stopping and Continuing
+To make the breakpoint stop the next time it is reached, specify
+a count of zero.
-When you run a program normally, it runs until it terminates. The
-principal purpose of using a debugger is so that you can stop it before
-that point; or so that if the program runs into trouble you can
-investigate and find out why.
+@item continue @var{count}
+@itemx c @var{count}
+@itemx fg @var{count}
+@kindex continue @var{count}
+Continue execution of your program, setting the ignore count of the
+breakpoint where your program stopped to @var{count} minus one.
+Thus, your program will not stop at this breakpoint until the
+@var{count}'th time it is reached.
-@menu
-* Signals:: Fatal signals in your program just stop it;
- then you can use _GDBN__ to see what is going on.
-* Breakpoints:: Breakpoints let you stop your program when it
- reaches a specified point in the code.
- an expression changes.
-* Continuing:: Resuming execution until the next signal or breakpoint.
-* Stepping:: Stepping runs the program a short distance and
- then stops it wherever it has come to.
-@end menu
+An argument to this command is meaningful only when your program stopped
+due to a breakpoint. At other times, the argument to @code{continue} is
+ignored.
-@node Signals, Breakpoints, Stopping, Stopping
-@section Signals
-@cindex signals
+The synonym @code{fg} is provided purely for convenience, and has
+exactly the same behavior as other forms of the command.
+@end table
-A signal is an asynchronous event that can happen in a program. The
-operating system defines the possible kinds of signals, and gives each kind
-a name and a number. For example, @code{SIGINT} is the signal a program
-gets when you type @kbd{Ctrl-c}; @code{SIGSEGV} is the signal a program
-gets from referencing a place in memory far away from all the areas in use;
-@code{SIGALRM} occurs when the alarm clock timer goes off (which happens
-only if the program has requested an alarm).
+If a breakpoint has a positive ignore count and a condition, the condition
+is not checked. Once the ignore count reaches zero, the condition will
+be checked.
-@cindex fatal signals
-Some signals, including @code{SIGALRM}, are a normal part of the
-functioning of the program. Others, such as @code{SIGSEGV}, indicate
-errors; these signals are @dfn{fatal} (kill the program immediately) if the
-program has not specified in advance some other way to handle the signal.
-@code{SIGINT} does not indicate an error in the program, but it is normally
-fatal so it can carry out the purpose of @kbd{Ctrl-c}: to kill the program.
+You could achieve the effect of the ignore count with a condition such
+as _0__@w{@samp{$foo-- <= 0}}_1__ using a debugger convenience variable that
+is decremented each time. @xref{Convenience Vars, ,Convenience
+Variables}.
-_GDBN__ has the ability to detect any occurrence of a signal in the program
-running under _GDBN__'s control. You can tell _GDBN__ in advance what to do for
-each kind of signal.
+@node Break Commands, Breakpoint Menus, Conditions, Breakpoints
+@subsection Breakpoint Command Lists
-@cindex handling signals
-Normally, _GDBN__ is set up to ignore non-erroneous signals like @code{SIGALRM}
-(so as not to interfere with their role in the functioning of the program)
-but to stop the program immediately whenever an error signal happens.
-You can change these settings with the @samp{handle} command.
+@cindex breakpoint commands
+You can give any breakpoint (or watchpoint) a series of commands to
+execute when your program stops due to that breakpoint. For example, you
+might want to print the values of certain expressions, or enable other
+breakpoints.
@table @code
-@item info signal
-@kindex info signal
-Print a table of all the kinds of signals and how _GDBN__ has been told to
-handle each one. You can use this to see the signal numbers of all
-the defined types of signals.
+@item commands @r{[}@var{bnum}@r{]}
+@itemx @dots{} @var{command-list} @dots{}
+@itemx end
+@kindex commands
+@kindex end
+Specify a list of commands for breakpoint number @var{bnum}. The commands
+themselves appear on the following lines. Type a line containing just
+@code{end} to terminate the commands.
-@item handle @var{signal} @var{keywords}@dots{}
-@kindex handle
-Change the way _GDBN__ handles signal @var{signal}. @var{signal} can be the
-number of a signal or its name (with or without the @samp{SIG} at the
-beginning). The @var{keywords} say what change to make.
+To remove all commands from a breakpoint, type @code{commands} and
+follow it immediately with @code{end}; that is, give no commands.
+
+With no @var{bnum} argument, @code{commands} refers to the last
+breakpoint or watchpoint set (not to the breakpoint most recently
+encountered).
@end table
-The keywords allowed by the @samp{handle} command can be abbreviated.
-Their full names are
+Pressing @key{RET} as a means of repeating the last _GDBN__ command is
+disabled within a @var{command-list}.
-@table @code
-@item nostop
-_GDBN__ should not stop the program when this signal happens. It may
-still print a message telling you that the signal has come in.
+You can use breakpoint commands to start your program up again. Simply
+use the @code{continue} command, or @code{step}, or any other command
+that resumes execution. Subsequent commands in the command list are
+ignored.
-@item stop
-_GDBN__ should stop the program when this signal happens. This implies
-the @samp{print} keyword as well.
+@kindex silent
+If the first command specified is @code{silent}, the usual message about
+stopping at a breakpoint is not printed. This may be desirable for
+breakpoints that are to print a specific message and then continue.
+If the remaining commands too print nothing, you will see no sign that
+the breakpoint was reached at all. @code{silent} is meaningful only
+at the beginning of a breakpoint command list.
-@item print
-_GDBN__ should print a message when this signal happens.
+The commands @code{echo} and @code{output} that allow you to print
+precisely controlled output are often useful in silent breakpoints.
+@xref{Output, ,Commands for Controlled Output}.
-@item noprint
-_GDBN__ should not mention the occurrence of the signal at all. This
-implies the @samp{nostop} keyword as well.
-
-@item pass
-_GDBN__ should allow the program to see this signal; the program will be
-able to handle the signal, or may be terminated if the signal is fatal
-and not handled.
+For example, here is how you could use breakpoint commands to print the
+value of @code{x} at entry to @code{foo} whenever @code{x} is positive.
-@item nopass
-_GDBN__ should not allow the program to see this signal.
-@end table
+_0__@example
+break foo if x>0
+commands
+silent
+echo x is\040
+output x
+echo \n
+cont
+end
+_1__@end example
-When a signal has been set to stop the program, the program cannot see the
-signal until you continue. It will see the signal then, if @samp{pass} is
-in effect for the signal in question @i{at that time}. In other words,
-after _GDBN__ reports a signal, you can use the @samp{handle} command with
-@samp{pass} or @samp{nopass} to control whether that signal will be seen by
-the program when you later continue it.
+One application for breakpoint commands is to compensate for one bug so
+you can test for another. Put a breakpoint just after the erroneous line
+of code, give it a condition to detect the case in which something
+erroneous has been done, and give it commands to assign correct values
+to any variables that need them. End with the @code{continue} command
+so that your program does not stop, and start with the @code{silent}
+command so that no output is produced. Here is an example:
-You can also use the @samp{signal} command to prevent the program from
-seeing a signal, or cause it to see a signal it normally would not see,
-or to give it any signal at any time. @xref{Signaling}.
+@example
+break 403
+commands
+silent
+set x = y + 4
+cont
+end
+@end example
-@node Breakpoints, Continuing, Signals, Stopping
-@section Breakpoints
+@cindex lost output
+One deficiency in the operation of automatically continuing breakpoints
+under Unix appears when your program uses raw mode for the terminal.
+_GDBN__ switches back to its own terminal modes (not raw) before executing
+commands, and then must switch back to raw mode when your program is
+continued. This causes any pending terminal input to be lost.
+@c FIXME: revisit below when GNU sys avail.
+@c In the GNU system, this will be fixed by changing the behavior of
+@c terminal modes.
-@cindex breakpoints
-A @dfn{breakpoint} makes your program stop whenever a certain point in the
-program is reached. You set breakpoints explicitly with _GDBN__ commands,
-specifying the place where the program should stop by line number, function
-name or exact address in the program. You can add various other conditions
-to control whether the program will stop.
-
-Each breakpoint is assigned a number when it is created; these numbers are
-successive integers starting with 1. In many of the commands for controlling
-various features of breakpoints you use the breakpoint number to say which
-breakpoint you want to change. Each breakpoint may be @dfn{enabled} or
-@dfn{disabled}; if disabled, it has no effect on the program until you
-enable it again.
+Under Unix, you can get around this problem by writing actions into
+the breakpoint condition rather than in commands. For example
-@table @code
-@kindex info break
-@kindex $_
-@item info break
-The command @samp{info break} prints a list of all breakpoints set and not
-deleted, showing their numbers, where in the program they are, and any
-special features in use for them. Disabled breakpoints are included in the
-list, but marked as disabled. @samp{info break} with a breakpoint number
-as argument lists only that breakpoint. The convenience variable @code{$_}
-and the default examining-address for the @samp{x} command are set to the
-address of the last breakpoint listed (@pxref{Memory}).
-
-@kindex info watch
-@item info watch
-This command prints a list of watchpoints.
+@example
+condition 5 (x = y + 4), 0
+@end example
-@cindex watchpoints
-A @dfn{watchpoint} is a special breakpoint that stops your program when
-the value of an expression changes. You can use a watchpoint to stop
-execution whenever the value of an expression changes, without having to
-predict a particular place in the inferior process where this may
-happen. Aside from the different syntax in setting a watchpoint, it is
-managed exactly like any other breakpoint and is enabled, disabled, and
-deleted using exactly the same commands.
+@noindent
+specifies a condition expression (@pxref{Expressions, ,Expressions}) that will
+change @code{x} as needed, then always have the value zero so your
+program will not stop. No input is lost here, because _GDBN__ evaluates
+break conditions without changing the terminal modes. When you want
+to have nontrivial conditions for performing the side effects, the
+operators @samp{&&}, @samp{||} and @samp{?@dots{}:} may be useful.
+
+@node Breakpoint Menus, Error in Breakpoints, Break Commands, Breakpoints
+@subsection Breakpoint Menus
+@cindex overloading
+@cindex symbol overloading
+
+Some programming languages (notably C++) permit a single function name
+to be defined several times, for application in different contexts.
+This is called @dfn{overloading}. When a function name is overloaded,
+@samp{break @var{function}} is not enough to tell _GDBN__ where you want
+a breakpoint. If you realize this will be a problem, you can use
+something like @samp{break @var{function}(@var{types})} to specify which
+particular version of the function you want. Otherwise, _GDBN__ offers
+you a menu of numbered choices for different possible breakpoints, and
+waits for your selection with the prompt @samp{>}. The first two
+options are always @samp{[0] cancel} and @samp{[1] all}. Typing @kbd{1}
+sets a breakpoint at each definition of @var{function}, and typing
+@kbd{0} aborts the @code{break} command without setting any new
+breakpoints.
+
+For example, the following session excerpt shows an attempt to set a
+breakpoint at the overloaded symbol @code{String::after}.
+We choose three particular definitions of that function name:
+
+@c FIXME! This is likely to change to show arg type lists, at least
+@example
+(_GDBP__) b String::after
+[0] cancel
+[1] all
+[2] file:String.cc; line number:867
+[3] file:String.cc; line number:860
+[4] file:String.cc; line number:875
+[5] file:String.cc; line number:853
+[6] file:String.cc; line number:846
+[7] file:String.cc; line number:735
+> 2 4 6
+Breakpoint 1 at 0xb26c: file String.cc, line 867.
+Breakpoint 2 at 0xb344: file String.cc, line 875.
+Breakpoint 3 at 0xafcc: file String.cc, line 846.
+Multiple breakpoints were set.
+Use the "delete" command to delete unwanted breakpoints.
+(_GDBP__)
+@end example
-Watchpoints currently execute two orders of magnitude more slowly than
-other breakpoints, but this can well be worth it to catch errors where
-you have no clue what part of your program is the culprit. Some
-processors provide special hardware to implement this feature; future
-releases of _GDBN__ will use such hardware if it is available.
+@node Error in Breakpoints, , Breakpoint Menus, Breakpoints
+@subsection ``Cannot Insert Breakpoints''
-@end table
+@c FIXME: "cannot insert breakpoints" error, v unclear.
+@c some light may be shed by looking at instances of
+@c ONE_PROCESS_WRITETEXT. But error message seems possible otherwise
+@c too. pesch, 20sep91
+Under some operating systems, breakpoints cannot be used in a program if
+any other process is running that program. In this situation,
+attempting to run or continue a program with a breakpoint causes _GDBN__
+to stop the other process.
-@menu
-* Set Breaks:: How to establish breakpoints.
-* Exception Handling:: How _GDBN__ supports exception handling for C++.
-* Delete Breaks:: How to remove breakpoints no longer needed.
-* Disabling:: How to disable breakpoints (turn them off temporarily).
-* Conditions:: Making extra conditions on whether to stop.
-* Break Commands:: Commands to be executed at a breakpoint.
-* Error in Breakpoints::
-@end menu
+When this happens, you have three ways to proceed:
-@node Set Breaks, Exception Handling, Breakpoints, Breakpoints
-@subsection Setting Breakpoints
+@enumerate
+@item
+Remove or disable the breakpoints, then continue.
-@kindex break
-@kindex watch
-Breakpoints are set with the @samp{break} command (abbreviated @samp{b}).
-Watchpoints are set with the @samp{watch} command.
+@item
+Suspend _GDBN__, and copy the file containing your program to a new name.
+Resume _GDBN__ and use the @code{exec-file} command to specify that _GDBN__
+should run your program under that name. Then start your program again.
-You have several ways to say where the breakpoint should go.
+@c FIXME: RMS commented here "Show example". Maybe when someone
+@c explains the first FIXME: in this section...
-@table @code
-@item break @var{function}
-Set a breakpoint at entry to function @var{function}.
+@item
+Relink your program so that the text segment is nonsharable, using the
+linker option @samp{-N}. The operating system limitation may not apply
+to nonsharable executables.
+@end enumerate
-@item break @var{+offset}
-@itemx break @var{-offset}
-Set a breakpoint some number of lines forward or back from the position
-at which execution stopped in the currently selected frame.
+@node Continuing and Stepping, Signals, Breakpoints, Stopping
+@section Continuing and Stepping
-@item break @var{linenum}
-Set a breakpoint at line @var{linenum} in the current source file.
-That file is the last file whose source text was printed. This
-breakpoint will stop the program just before it executes any of the
-code on that line.
+@cindex stepping
+@cindex continuing
+@cindex resuming execution
+@dfn{Continuing} means resuming program execution until your program
+completes normally. In contrast, @dfn{stepping} means executing just
+one more ``step'' of your program, where ``step'' may mean either one
+line of source code, or one machine instruction (depending on what
+particular command you use). Either when continuing
+or when stepping, your program may stop even sooner, due to a breakpoint
+or to a signal. (If due to a signal, you may want to use @code{handle},
+or use @samp{signal 0} to resume execution. @xref{Signals, ,Signals}.)
-@item break @var{filename}:@var{linenum}
-Set a breakpoint at line @var{linenum} in source file @var{filename}.
+@table @code
+@item continue @r{[}@var{ignore-count}@r{]}
+@kindex continue
+Resume program execution, at the address where your program last stopped;
+any breakpoints set at that address are bypassed. The optional argument
+@var{ignore-count} allows you to specify a further number of times to
+ignore a breakpoint at this location; its effect is like that of
+@code{ignore} (@pxref{Conditions, ,Break Conditions}).
+
+To resume execution at a different place, you can use @code{return}
+(@pxref{Returning, ,Returning from a Function}) to go back to the
+calling function; or @code{jump} (@pxref{Jumping, ,Continuing at a
+Different Address}) to go to an arbitrary location in your program.
+@end table
-@item break @var{filename}:@var{function}
-Set a breakpoint at entry to function @var{function} found in file
-@var{filename}. Specifying a file name as well as a function name is
-superfluous except when multiple files contain similarly named
-functions.
+A typical technique for using stepping is to set a breakpoint
+(@pxref{Breakpoints, ,Breakpoints Watchpoints and Exceptions}) at the
+beginning of the function or the section of your program where a
+problem is believed to lie, run your program until it stops at that
+breakpoint, and then step through the suspect area, examining the
+variables that are interesting, until you see the problem happen.
-@item break *@var{address}
-Set a breakpoint at address @var{address}. You can use this to set
-breakpoints in parts of the program which do not have debugging
-information or source files.
+@table @code
+@item step
+@kindex step
+@kindex s
+Continue running your program until control reaches a different source
+line, then stop it and return control to _GDBN__. This command is
+abbreviated @code{s}.
-@item break
-Set a breakpoint at the next instruction to be executed in the selected
-stack frame (@pxref{Stack}). In any selected frame but the innermost,
-this will cause the program to stop as soon as control returns to that
-frame. This is equivalent to a @samp{finish} command in the frame
-inside the selected frame. If this is done in the innermost frame, _GDBN__
-will stop the next time it reaches the current location; this may be
-useful inside of loops.
+@quotation
+@emph{Warning:} If you use the @code{step} command while control is
+within a function that was compiled without debugging information,
+execution will proceed until control reaches another function.
+@end quotation
-_GDBN__ normally ignores breakpoints when it resumes execution, until at
-least one instruction has been executed. If it did not do this, you
-would be unable to proceed past a breakpoint without first disabling the
-breakpoint. This rule applies whether or not the breakpoint already
-existed when the program stopped.
+@item step @var{count}
+Continue running as in @code{step}, but do so @var{count} times. If a
+breakpoint is reached or a signal not related to stepping occurs before
+@var{count} steps, stepping stops right away.
-@item break @dots{} if @var{cond}
-Set a breakpoint with condition @var{cond}; evaluate the expression
-@var{cond} each time the breakpoint is reached, and stop only if the
-value is nonzero. @samp{@dots{}} stands for one of the possible
-arguments described above (or no argument) specifying where to break.
-@xref{Conditions}, for more information on breakpoint conditions.
+@item next @r{[}@var{count}@r{]}
+@kindex next
+@kindex n
+Continue to the next source line in the current (innermost) stack frame.
+Similar to @code{step}, but any function calls appearing within the line
+of code are executed without stopping. Execution stops when control
+reaches a different line of code at the stack level which was executing
+when the @code{next} command was given. This command is abbreviated
+@code{n}.
+
+An argument @var{count} is a repeat count, as for @code{step}.
+
+@code{next} within a function that lacks debugging information acts like
+@code{step}, but any function calls appearing within the code of the
+function are executed without stopping.
-@item tbreak @var{args}
-@kindex tbreak
-Set a breakpoint enabled only for one stop. @var{args} are the
-same as in the @samp{break} command, and the breakpoint is set in the same
-way, but the breakpoint is automatically disabled the first time it
-is hit. @xref{Disabling}.
+@item finish
+@kindex finish
+Continue running until just after function in the selected stack frame
+returns. Print the returned value (if any).
-@item rbreak @var{regex}
-@kindex rbreak
-Set a breakpoint on all functions matching @var{regex}. This is
-useful for setting breakpoints on overloaded functions that are not
-members of any special classes. This command sets an unconditional
-breakpoint on all matches, printing a list of all breakpoints it set.
-Once these breakpoints are set, they are treated just like the
-breakpoints set with the @samp{break} command. They can be deleted,
-disabled, made conditional, etc., in the standard ways.
-
-@kindex watch
-@item watch @var{expr}
-Set a watchpoint for an expression.
-@end table
+Contrast this with the @code{return} command (@pxref{Returning,
+,Returning from a Function}).
-_GDBN__ allows you to set any number of breakpoints at the same place in the
-program. There is nothing silly or meaningless about this. When the
-breakpoints are conditional, this is even useful (@pxref{Conditions}).
+@item until
+@kindex until
+@item u
+@kindex u
+Continue running until a source line past the current line, in the
+current stack frame, is reached. This command is used to avoid single
+stepping through a loop more than once. It is like the @code{next}
+command, except that when @code{until} encounters a jump, it
+automatically continues execution until the program counter is greater
+than the address of the jump.
-@node Exception Handling, Delete Breaks, Set Breaks, Breakpoints
-@subsection Breakpoints and Exceptions
-@cindex exception handlers
+This means that when you reach the end of a loop after single stepping
+though it, @code{until} will cause your program to continue execution
+until the loop is exited. In contrast, a @code{next} command at the end
+of a loop will simply step back to the beginning of the loop, which
+would force you to step through the next iteration.
-Some languages, such as GNU C++, implement exception handling. _GDBN__
-can be used to examine what caused the program to raise an exception
-and to list the exceptions the program is prepared to handle at a
-given point in time.
+@code{until} always stops your program if it attempts to exit the current
+stack frame.
-@cindex raise exceptions
-GNU C++ raises an exception by calling a library function named
-@code{__raise_exception} which has the following ANSI C interface:
+@code{until} may produce somewhat counterintuitive results if the order
+of machine code does not match the order of the source lines. For
+example, in the following excerpt from a debugging session, the @code{f}
+(@code{frame}) command shows that execution is stopped at line
+@code{206}; yet when we use @code{until}, we get to line @code{195}:
@example
- /* ADDR is where the exception identifier is stored.
- ID is the exception identifier. */
- void __raise_exception (void **addr, void *id);
+(_GDBP__) f
+#0 main (argc=4, argv=0xf7fffae8) at m4.c:206
+206 expand_input();
+(_GDBP__) until
+195 for ( ; argc > 0; NEXTARG) @{
@end example
-@noindent
-You can make the debugger catch all exceptions @emph{before} any stack
-unwinding takes place: set a breakpoint on @code{__raise_exception}
-(@pxref{Breakpoints}). If you set a breakpoint in an exception handler
-instead, it may not be easy to find out where the exception was raised.
+This happened because, for execution efficiency, the compiler had
+generated code for the loop closure test at the end, rather than the
+start, of the loop---even though the test in a C @code{for}-loop is
+written before the body of the loop. The @code{until} command appeared
+to step back to the beginning of the loop when it advanced to this
+expression; however, it has not really gone to an earlier
+statement---not in terms of the actual machine code.
-By using a conditional breakpoint (@xref{Conditions}), you can cause
-the debugger to stop only when a specific exception is raised.
-Multiple conditional breakpoints can be used to stop the program when
-any of a number of exceptions are raised.
+@code{until} with no argument works by means of single
+instruction stepping, and hence is slower than @code{until} with an
+argument.
-@table @code
-@item catch @var{exceptions}
-@kindex catch
+@item until @var{location}
+@item u @var{location}
+Continue running your program until either the specified location is
+reached, or the current stack frame returns. @var{location} is any of
+the forms of argument acceptable to @code{break} (@pxref{Set Breaks,
+,Setting Breakpoints}). This form of the command uses breakpoints,
+and hence is quicker than @code{until} without an argument.
-Breakpoints can be set at active exception handlers by using the
-@samp{catch} command. @var{exceptions} is a list of names of exceptions
-to catch.
-@end table
+@item stepi
+@itemx si
+@kindex stepi
+@kindex si
+Execute one machine instruction, then stop and return to the debugger.
-You can use @samp{info catch} to list active exception handlers;
-@pxref{Frame Info}.
+It is often useful to do @samp{display/i $pc} when stepping by machine
+instructions. This will cause the next instruction to be executed to
+be displayed automatically at each stop. @xref{Auto Display,
+,Automatic Display}.
-There are currently some limitations to exception handling in _GDBN__.
-These will be corrected in a future release.
+An argument is a repeat count, as in @code{step}.
-@itemize @bullet
-@item
-If you call a function interactively, _GDBN__ will normally return
-control to you when the function has finished executing. If the call
-raises an exception, however, the call may bypass the mechanism that
-returns control to the user and cause the program to simply continue
-running until it hits a breakpoint, catches a signal that _GDBN__ is
-listening for, or exits.
-@item
-You cannot raise an exception interactively.
-@item
-You cannot interactively install an exception handler.
-@end itemize
+@item nexti
+@itemx ni
+@kindex nexti
+@kindex ni
+Execute one machine instruction, but if it is a function call,
+proceed until the function returns.
-@node Delete Breaks, Disabling, Exception Handling, Breakpoints
-@subsection Deleting Breakpoints
+An argument is a repeat count, as in @code{next}.
+@end table
-@cindex clearing breakpoints, watchpoints
-@cindex deleting breakpoints, watchpoints
-It is often necessary to eliminate a breakpoint once it has done its job
-and you no longer want the program to stop there. This is called
-@dfn{deleting} the breakpoint. A breakpoint that has been deleted no
-longer exists in any sense; it is forgotten.
+@node Signals, , Continuing and Stepping, Stopping
+@section Signals
+@cindex signals
-With the @samp{clear} command you can delete breakpoints according to where
-they are in the program. With the @samp{delete} command you can delete
-individual breakpoints by specifying their breakpoint numbers.
+A signal is an asynchronous event that can happen in a program. The
+operating system defines the possible kinds of signals, and gives each
+kind a name and a number. For example, in Unix @code{SIGINT} is the
+signal a program gets when you type an interrupt (often @kbd{C-c});
+@code{SIGSEGV} is the signal a program gets from referencing a place in
+memory far away from all the areas in use; @code{SIGALRM} occurs when
+the alarm clock timer goes off (which happens only if your program has
+requested an alarm).
-It is not necessary to delete a breakpoint to proceed past it. _GDBN__
-automatically ignores breakpoints on the first instruction to be executed
-when you continue execution without changing the execution address.
+@cindex fatal signals
+Some signals, including @code{SIGALRM}, are a normal part of the
+functioning of your program. Others, such as @code{SIGSEGV}, indicate
+errors; these signals are @dfn{fatal} (kill your program immediately) if the
+program has not specified in advance some other way to handle the signal.
+@code{SIGINT} does not indicate an error in your program, but it is normally
+fatal so it can carry out the purpose of the interrupt: to kill the program.
-@table @code
-@item clear
-@kindex clear
-Delete any breakpoints at the next instruction to be executed in the
-selected stack frame (@pxref{Selection}). When the innermost frame
-is selected, this is a good way to delete a breakpoint that the program
-just stopped at.
+_GDBN__ has the ability to detect any occurrence of a signal in your
+program. You can tell _GDBN__ in advance what to do for each kind of
+signal.
-@item clear @var{function}
-@itemx clear @var{filename}:@var{function}
-Delete any breakpoints set at entry to the function @var{function}.
+@cindex handling signals
+Normally, _GDBN__ is set up to ignore non-erroneous signals like @code{SIGALRM}
+(so as not to interfere with their role in the functioning of your program)
+but to stop your program immediately whenever an error signal happens.
+You can change these settings with the @code{handle} command.
-@item clear @var{linenum}
-@itemx clear @var{filename}:@var{linenum}
-Delete any breakpoints set at or within the code of the specified line.
+@table @code
+@item info signals
+@kindex info signals
+Print a table of all the kinds of signals and how _GDBN__ has been told to
+handle each one. You can use this to see the signal numbers of all
+the defined types of signals.
-@item delete breakpoints @var{bnums}@dots{}
-@itemx delete @var{bnums}@dots{}
-@itemx delete
-@kindex delete breakpoints
-@kindex delete
-Delete the breakpoints of the numbers specified as arguments. If no
-argument is specified, delete all breakpoints.
+@item handle @var{signal} @var{keywords}@dots{}
+@kindex handle
+Change the way _GDBN__ handles signal @var{signal}. @var{signal} can be the
+number of a signal or its name (with or without the @samp{SIG} at the
+beginning). The @var{keywords} say what change to make.
@end table
-@node Disabling, Conditions, Delete Breaks, Breakpoints
-@subsection Disabling Breakpoints
-
-@cindex disabled breakpoints
-@cindex enabled breakpoints
-Rather than deleting a breakpoint, you might prefer to @dfn{disable} it.
-This makes the breakpoint inoperative as if it had been deleted, but
-remembers the information on the breakpoint so that you can @dfn{enable}
-it again later.
+@c @group
+The keywords allowed by the @code{handle} command can be abbreviated.
+Their full names are:
-You disable and enable breakpoints with the @samp{enable} and
-@samp{disable} commands, optionally specifying one or more breakpoint
-numbers as arguments. Use @samp{info break} to print a list of
-breakpoints if you don't know which breakpoint numbers to use.
+@table @code
+@item nostop
+_GDBN__ should not stop your program when this signal happens. It may
+still print a message telling you that the signal has come in.
-A breakpoint can have any of four different states of enablement:
+@item stop
+_GDBN__ should stop your program when this signal happens. This implies
+the @code{print} keyword as well.
-@itemize @bullet
-@item
-Enabled. The breakpoint will stop the program. A breakpoint made
-with the @samp{break} command starts out in this state.
-@item
-Disabled. The breakpoint has no effect on the program.
-@item
-Enabled once. The breakpoint will stop the program, but
-when it does so it will become disabled. A breakpoint made
-with the @samp{tbreak} command starts out in this state.
-@item
-Enabled for deletion. The breakpoint will stop the program, but
-immediately after it does so it will be deleted permanently.
-@end itemize
+@item print
+_GDBN__ should print a message when this signal happens.
-You can use the following commands to enable or disable a breakpoint:
+@item noprint
+_GDBN__ should not mention the occurrence of the signal at all. This
+implies the @code{nostop} keyword as well.
-@table @code
-@item disable breakpoints @var{bnums}@dots{}
-@itemx disable @var{bnums}@dots{}
-@itemx disable
-@kindex disable breakpoints
-@kindex disable
-Disable the specified breakpoints---or all breakpoints, if none are
-listed. A disabled breakpoint has no effect but is not forgotten. All
-options such as ignore-counts, conditions and commands are remembered in
-case the breakpoint is enabled again later.
+@item pass
+_GDBN__ should allow your program to see this signal; your program will be
+able to handle the signal, or may be terminated if the signal is fatal
+and not handled.
-@item enable breakpoints @var{bnums}@dots{}
-@itemx enable @var{bnums}@dots{}
-@itemx enable
-@kindex enable breakpoints
-@kindex enable
-Enable the specified breakpoints (or all defined breakpoints). They
-become effective once again in stopping the program, until you specify
-otherwise.
+@item nopass
+_GDBN__ should not allow your program to see this signal.
+@end table
+@c @end group
-@item enable breakpoints once @var{bnums}@dots{}
-@itemx enable once @var{bnums}@dots{}
-Enable the specified breakpoints temporarily. Each will be disabled
-again the next time it stops the program (unless you have used one of
-these commands to specify a different state before that time comes).
+When a signal has been set to stop your program, your program cannot see the
+signal until you continue. It will see the signal then, if @code{pass} is
+in effect for the signal in question @emph{at that time}. In other words,
+after _GDBN__ reports a signal, you can use the @code{handle} command with
+@code{pass} or @code{nopass} to control whether that signal will be seen by
+your program when you later continue it.
-@item enable breakpoints delete @var{bnums}@dots{}
-@itemx enable delete @var{bnums}@dots{}
-Enable the specified breakpoints to work once and then die. Each of
-the breakpoints will be deleted the next time it stops the program
-(unless you have used one of these commands to specify a different
-state before that time comes).
-@end table
+You can also use the @code{signal} command to prevent your program from
+seeing a signal, or cause it to see a signal it normally would not see,
+or to give it any signal at any time. For example, if your program stopped
+due to some sort of memory reference error, you might store correct
+values into the erroneous variables and continue, hoping to see more
+execution; but your program would probably terminate immediately as
+a result of the fatal signal once it saw the signal. To prevent this,
+you can continue with @samp{signal 0}. @xref{Signaling, ,Giving your
+Program a Signal}.
-Save for a breakpoint set with @samp{tbreak} (@pxref{Set Breaks}),
-breakpoints that you set are enabled or disabled only when you use one
-of the commands above. (The command @samp{until} can set and delete a
-breakpoint on its own, but it will not change the state of your
-breakpoints).
+@node Stack, Source, Stopping, Top
+@chapter Examining the Stack
-@node Conditions, Break Commands, Disabling, Breakpoints
-@subsection Break Conditions
-@cindex conditional breakpoints
-@cindex breakpoint conditions
+When your program has stopped, the first thing you need to know is where it
+stopped and how it got there.
-The simplest sort of breakpoint breaks every time the program reaches a
-specified place. You can also specify a @dfn{condition} for a
-breakpoint. A condition is just a boolean expression in your
-programming language. (@xref{Expressions}). A breakpoint with a
-condition evaluates the expression each time the program reaches it, and
-the program stops only if the condition is true.
-
-Break conditions may have side effects, and may even call functions in your
-program. These may sound like strange things to do, but their effects are
-completely predictable unless there is another enabled breakpoint at the
-same address. (In that case, _GDBN__ might see the other breakpoint first and
-stop the program without checking the condition of this one.) Note that
-breakpoint commands are usually more convenient and flexible for the
-purpose of performing side effects when a breakpoint is reached
-(@pxref{Break Commands}).
+@cindex call stack
+Each time your program performs a function call, the information about
+where in your program the call was made from is saved in a block of data
+called a @dfn{stack frame}. The frame also contains the arguments of the
+call and the local variables of the function that was called. All the
+stack frames are allocated in a region of memory called the @dfn{call
+stack}.
-Break conditions can be specified when a breakpoint is set, by using
-@samp{if} in the arguments to the @samp{break} command. @xref{Set Breaks}.
-They can also be changed at any time with the @samp{condition} command:
-
-@table @code
-@item condition @var{bnum} @var{expression}
-@kindex condition
-Specify @var{expression} as the break condition for breakpoint number
-@var{bnum}. From now on, this breakpoint will stop the program only if
-the value of @var{expression} is true (nonzero, in C). @var{expression}
-is not evaluated at the time the @samp{condition} command is given.
-When you call @samp{condition}, the expression you specify is checked
-immediately for syntactic correctness, and to determine whether symbols
-in it have referents in the context of your breakpoint.
-@xref{Expressions}.
-
-@item condition @var{bnum}
-Remove the condition from breakpoint number @var{bnum}. It becomes
-an ordinary unconditional breakpoint.
-@end table
-
-@cindex ignore count (of breakpoint)
-A special case of a breakpoint condition is to stop only when the
-breakpoint has been reached a certain number of times. This is so
-useful that there is a special way to do it, using the @dfn{ignore
-count} of the breakpoint. Every breakpoint has an ignore count, which
-is an integer. Most of the time, the ignore count is zero, and
-therefore has no effect. But if the program reaches a breakpoint whose
-ignore count is positive, then instead of stopping, it just decrements
-the ignore count by one and continues. As a result, if the ignore count
-value is @var{n}, the breakpoint will not stop the next @var{n} times it
-is reached.
-
-@table @code
-@item ignore @var{bnum} @var{count}
-@kindex ignore
-Set the ignore count of breakpoint number @var{bnum} to @var{count}.
-The next @var{count} times the breakpoint is reached, your program's
-execution will not stop; other than to decrement the ignore count, _GDBN__
-takes no action.
-
-To make the breakpoint stop the next time it is reached, specify
-a count of zero.
-
-@item continue @var{count}
-@itemx cont @var{count}
-@itemx c @var{count}
-@itemx fg @var{count}
-@kindex cont @var{count}
-@kindex continue @var{count}
-Continue execution of the program, setting the ignore count of the
-breakpoint that the program stopped at to @var{count} minus one.
-Thus, the program will not stop at this breakpoint until the
-@var{count}'th time it is reached.
-
-This command is allowed only when the program stopped due to a
-breakpoint. At other times, the argument to @samp{cont} is ignored.
-
-The synonym @samp{fg} is provided purely for convenience, and has
-exactly the same behavior as other forms of the command.
-@end table
-
-If a breakpoint has a positive ignore count and a condition, the condition
-is not checked. Once the ignore count reaches zero, the condition will
-be checked.
-
-Note that you could achieve the effect of the ignore count with a
-condition such as @w{@samp{$foo-- <= 0}} using a debugger convenience
-variable that is decremented each time. @xref{Convenience Vars}.
-
-@node Break Commands, Error in Breakpoints, Conditions, Breakpoints
-@subsection Commands Executed on Breaking
-
-@cindex breakpoint commands
-You can give any breakpoint a series of commands to execute when the
-program stops due to that breakpoint. For example, you might want to
-print the values of certain expressions, or enable other breakpoints.
-
-@table @code
-@item commands @var{bnum}
-@kindex commands
-Specify a list of commands for breakpoint number @var{bnum}. The commands
-themselves appear on the following lines. Type a line containing just
-@samp{end} to terminate the commands.
-
-To remove all commands from a breakpoint, use the command
-@samp{commands} and follow it immediately by @samp{end}; that is, give
-no commands.
-
-With no arguments, @samp{commands} refers to the last breakpoint set
-(not to the breakpoint most recently encountered).
-@end table
-
-You can use breakpoint commands to start the program up again. Simply
-use the @samp{cont} command, or @samp{step}, or any other command to
-resume execution. However, if you do this, any further commands in the
-same breakpoint's command list are ignored. When the program stops
-again, _GDBN__ will act according to the cause of that stop.
-
-@kindex silent
-If the first command specified is @samp{silent}, the usual message about
-stopping at a breakpoint is not printed. This may be desirable for
-breakpoints that are to print a specific message and then continue.
-If the remaining commands too print nothing, you will see no sign that
-the breakpoint was reached at all. @samp{silent} is not really a command;
-it is meaningful only at the beginning of the commands for a breakpoint.
-
-The commands @samp{echo} and @samp{output} that allow you to print precisely
-controlled output are often useful in silent breakpoints. @xref{Output}.
-
-For example, here is how you could use breakpoint commands to print the
-value of @code{x} at entry to @code{foo} whenever it is positive.
-
-@example
-break foo if x>0
-commands
-silent
-echo x is\040
-output x
-echo \n
-cont
-end
-@end example
-
-One application for breakpoint commands is to correct one bug so you can
-test another. Put a breakpoint just after the erroneous line of code, give
-it a condition to detect the case in which something erroneous has been
-done, and give it commands to assign correct values to any variables that
-need them. End with the @samp{cont} command so that the program does not
-stop, and start with the @samp{silent} command so that no output is
-produced. Here is an example:
-
-@example
-break 403
-commands
-silent
-set x = y + 4
-cont
-end
-@end example
-
-One deficiency in the operation of automatically continuing breakpoints
-under Unix appears when your program uses raw mode for the terminal.
-_GDBN__ switches back to its own terminal modes (not raw) before executing
-commands, and then must switch back to raw mode when your program is
-continued. This causes any pending terminal input to be lost.
-In the GNU system, this will be fixed by changing the behavior of
-terminal modes.
-
-Under Unix, when you have this problem, you might be able to get around
-it by putting your actions into the breakpoint condition instead of
-commands. For example
-
-@example
-condition 5 (x = y + 4), 0
-@end example
-
-@noindent
-specifies a condition expression (@xref{Expressions}) that will change
-@code{x} as needed, then always have the value 0 so the program will not
-stop. Loss of input is avoided here because break conditions are
-evaluated without changing the terminal modes. When you want to have
-nontrivial conditions for performing the side effects, the operators
-@samp{&&}, @samp{||} and @samp{?@dots{}:} may be useful.
-
-@node Error in Breakpoints, , Break Commands, Breakpoints
-@subsection ``Cannot Insert Breakpoints''
-
-@c FIXME: "cannot insert breakpoints" error, v unclear.
-Under some operating systems, breakpoints cannot be used in a program if
-any other process is running that program. In this situation,
-attempting to run or continue a program with a breakpoint will cause _GDBN__
-to stop the other process.
-
-When this happens, you have three ways to proceed:
-
-@enumerate
-@item
-Remove or disable the breakpoints, then continue.
-
-@item
-Suspend _GDBN__, and copy the file containing the program to a new name.
-Resume _GDBN__ and use the @samp{exec-file} command to specify that _GDBN__
-should run the program under that name. Then start the program again.
-
-@item
-Relink the program so that the text segment is nonsharable, using the
-linker option @samp{-N}. The operating system limitation may not apply
-to nonsharable executables.
-@end enumerate
-
-@node Continuing, Stepping, Breakpoints, Stopping
-@section Continuing
-
-After your program stops, most likely you will want it to run some more if
-the bug you are looking for has not happened yet.
-
-@table @code
-@item continue
-@item cont
-@kindex cont
-@kindex continue
-Continue running the program at the place where it stopped.
-@end table
-
-If the program stopped at a breakpoint, the place to continue running
-is the address of the breakpoint. You might expect that continuing would
-just stop at the same breakpoint immediately. In fact, @samp{cont}
-takes special care to prevent that from happening. You do not need
-to delete the breakpoint to proceed through it after stopping at it.
-
-You can, however, specify an ignore-count for the breakpoint that the
-program stopped at, by means of an argument to the @samp{cont} command.
-@xref{Conditions}.
-
-If the program stopped because of a signal other than @code{SIGINT} or
-@code{SIGTRAP}, continuing will cause the program to see that signal.
-You may not want this to happen. For example, if the program stopped
-due to some sort of memory reference error, you might store correct
-values into the erroneous variables and continue, hoping to see more
-execution; but the program would probably terminate immediately as
-a result of the fatal signal once it sees the signal. To prevent this,
-you can continue with @samp{signal 0}. @xref{Signaling}. You can
-also act in advance to control what signals your program will see, using
-the @samp{handle} command (@pxref{Signals}).
-
-@node Stepping, , Continuing, Stopping
-@section Stepping
-
-@cindex stepping
-@dfn{Stepping} means setting your program in motion for a limited time, so
-that control will return automatically to the debugger after one line of
-code or one machine instruction. Breakpoints are active during stepping
-and the program will stop for them even if it has not gone as far as the
-stepping command specifies.
-
-@table @code
-@item step
-@kindex step
-Continue running the program until control reaches a different line,
-then stop it and return control to the debugger. This command is
-abbreviated @samp{s}.
-
-This command may be given when control is within a function for which
-there is no debugging information. In that case, execution will proceed
-until control reaches a different function, or is about to return from
-this function. An argument repeats this action.
-
-@item step @var{count}
-Continue running as in @samp{step}, but do so @var{count} times. If a
-breakpoint is reached or a signal not related to stepping occurs before
-@var{count} steps, stepping stops right away.
-
-@item next
-@kindex next
-Similar to @samp{step}, but any function calls appearing within the line of
-code are executed without stopping. Execution stops when control reaches a
-different line of code at the stack level which was executing when the
-@samp{next} command was given. This command is abbreviated @samp{n}.
-
-An argument is a repeat count, as in @samp{step}.
-
-@samp{next} within a function without debugging information acts as does
-@samp{step}, but any function calls appearing within the code of the
-function are executed without stopping.
-
-@item finish
-@kindex finish
-Continue running until just after the selected stack frame returns (or
-until there is some other reason to stop, such as a fatal signal or a
-breakpoint). Print value returned by the selected stack frame (if any).
-
-Contrast this with the @samp{return} command (@pxref{Returning}).
-
-@item until
-@kindex until
-This command is used to avoid single stepping through a loop more than
-once. It is like the @samp{next} command, except that when @samp{until}
-encounters a jump, it automatically continues execution until the
-program counter is greater than the address of the jump.
-
-This means that when you reach the end of a loop after single stepping
-though it, @samp{until} will cause the program to continue execution
-until the loop is exited. In contrast, a @samp{next} command at the end
-of a loop will simply step back to the beginning of the loop, which
-would force you to step through the next iteration.
-
-@samp{until} always stops the program if it attempts to exit the current
-stack frame.
-
-@samp{until} may produce somewhat counterintuitive results if the order
-of the source lines does not match the actual order of execution. For
-example, in a typical C @code{for}-loop, the third expression in the
-@code{for}-statement (the loop-step expression) is executed after the
-statements in the body of the loop, but is written before them.
-Therefore, the @samp{until} command would appear to step back to the
-beginning of the loop when it advances to this expression. However, it
-has not really done so, not in terms of the actual machine code.
-
-Note that @samp{until} with no argument works by means of single
-instruction stepping, and hence is slower than @samp{until} with an
-argument.
-
-@item until @var{location}
-Continue running the program until either the specified location is
-reached, or the current (innermost) stack frame returns. @var{location}
-is any of the forms of argument acceptable to @samp{break} (@pxref{Set
-Breaks}). This form of the command uses breakpoints, and hence is
-quicker than @samp{until} without an argument.
-
-@item stepi
-@itemx si
-@kindex stepi
-@kindex si
-Execute one machine instruction, then stop and return to the debugger.
-
-It is often useful to do @samp{display/i $pc} when stepping by machine
-instructions. This will cause the next instruction to be executed to
-be displayed automatically at each stop. @xref{Auto Display}.
-
-An argument is a repeat count, as in @samp{step}.
-
-@item nexti
-@itemx ni
-@kindex nexti
-@kindex ni
-Execute one machine instruction, but if it is a subroutine call,
-proceed until the subroutine returns.
-
-An argument is a repeat count, as in @samp{next}.
-@end table
-
-A typical technique for using stepping is to put a breakpoint
-(@pxref{Breakpoints}) at the beginning of the function or the section of
-the program in which a problem is believed to lie, and then step through
-the suspect area, examining the variables that are interesting, until the
-problem happens.
-
-The @samp{cont} command can be used after stepping to resume execution
-until the next breakpoint or signal.
-
-@node Stack, Source, Stopping, Top
-@chapter Examining the Stack
-
-When your program has stopped, the first thing you need to know is where it
-stopped and how it got there.
-
-@cindex call stack
-Each time your program performs a function call, the information about
-where in the program the call was made from is saved in a block of data
-called a @dfn{stack frame}. The frame also contains the arguments of the
-call and the local variables of the function that was called. All the
-stack frames are allocated in a region of memory called the @dfn{call
-stack}.
-
-When your program stops, the _GDBN__ commands for examining the stack allow you
-to see all of this information.
+When your program stops, the _GDBN__ commands for examining the stack allow you
+to see all of this information.
+@cindex selected frame
One of the stack frames is @dfn{selected} by _GDBN__ and many _GDBN__ commands
refer implicitly to the selected frame. In particular, whenever you ask
-_GDBN__ for the value of a variable in the program, the value is found in the
+_GDBN__ for the value of a variable in your program, the value is found in the
selected frame. There are special _GDBN__ commands to select whichever frame
you are interested in.
-When the program stops, _GDBN__ automatically selects the currently executing
-frame and describes it briefly as the @samp{frame} command does
-(@pxref{Frame Info, Info}).
+When your program stops, _GDBN__ automatically selects the currently executing
+frame and describes it briefly as the @code{frame} command does
+(@pxref{Frame Info, ,Information About a Frame}).
@menu
-* Frames:: Explanation of stack frames and terminology.
-* Backtrace:: Summarizing many frames at once.
-* Selection:: How to select a stack frame.
-* Frame Info:: Information on a Frame
+* Frames:: Stack Frames
+* Backtrace:: Backtraces
+* Selection:: Selecting a Frame
+* Frame Info:: Information on a Frame
@end menu
@node Frames, Backtrace, Stack, Stack
going on in that frame.
@cindex frame number
-_GDBN__ assigns numbers to all existing stack frames, starting with zero for
-the innermost frame, one for the frame that called it, and so on upward.
-These numbers do not really exist in your program; they are to give you a
-way of talking about stack frames in _GDBN__ commands.
-
-@cindex selected frame
-Many _GDBN__ commands refer implicitly to one stack frame, called the
-@dfn{selected} stack frame. You can select any frame using one set of
-_GDBN__ commands, and then other commands will operate on that frame. When
-your program stops, _GDBN__ automatically selects the innermost frame.
+_GDBN__ assigns numbers to all existing stack frames, starting with
+zero for the innermost frame, one for the frame that called it,
+and so on upward. These numbers do not really exist in your program;
+they are assigned by _GDBN__ to give you a way of designating stack
+frames in _GDBN__ commands.
@cindex frameless execution
-Some compilers allow functions to be compiled to run without a frame
-reserved for them on the stack. (For example, the _GCC__ option
+Some compilers allow functions to be compiled so that they operate
+without stack frames. (For example, the @code{_GCC__} option
@samp{-fomit-frame-pointer} will generate functions without a frame.)
This is occasionally done with heavily used library functions to save
-the frame setup time. _GDBN__ has limited facilities for dealing with these
-function invocations; if the innermost function invocation has no stack
-frame, _GDBN__ will give it a virtual stack frame of 0 and correctly allow
-tracing of the function call chain. Results are undefined if a function
-invocation besides the innermost one is frameless.
+the frame setup time. _GDBN__ has limited facilities for dealing with
+these function invocations. If the innermost function invocation has no
+stack frame, _GDBN__ will nevertheless regard it as though it had a
+separate frame, which is numbered zero as usual, allowing correct
+tracing of the function call chain. However, _GDBN__ has no provision
+for frameless functions elsewhere in the stack.
@node Backtrace, Selection, Frames, Stack
@section Backtraces
-A backtrace is a summary of how the program got where it is. It shows one
+A backtrace is a summary of how your program got where it is. It shows one
line per frame, for many frames, starting with the currently executing
frame (frame zero), followed by its caller (frame one), and on up the
stack.
frames in the stack.
You can stop the backtrace at any time by typing the system interrupt
-character, normally @kbd{Control-C}.
+character, normally @kbd{C-c}.
@item backtrace @var{n}
@itemx bt @var{n}
Similar, but print only the innermost @var{n} frames.
-@item backtrace @var{-n}
-@itemx bt @var{-n}
+@item backtrace -@var{n}
+@itemx bt -@var{n}
Similar, but print only the outermost @var{n} frames.
@end table
@kindex where
@kindex info stack
-The names @samp{where} and @samp{info stack} are additional aliases
-for @samp{backtrace}.
-
-Every line in the backtrace shows the frame number and the function
-name. The program counter value is also shown---unless you use
-@samp{set addressprint off}.
+@kindex info s
+The names @code{where} and @code{info stack} (abbreviated @code{info s})
+are additional aliases for @code{backtrace}.
-If the function is in a source file whose symbol table data has been
-fully read, the backtrace shows the source file name and line number, as
-well as the arguments to the function. When the line number is shown,
-the program counter value is omitted if it is at the beginning of the
-code for that line number.
+Each line in the backtrace shows the frame number and the function name.
+The program counter value is also shown---unless you use @code{set
+print address off}. The backtrace also shows the source file name and
+line number, as well as the arguments to the function. The program
+counter value is omitted if it is at the beginning of the code for that
+line number.
Here is an example of a backtrace. It was made with the command
@samp{bt 3}, so it shows the innermost three frames.
-@example
-#0 rtx_equal_p (x=(rtx) 0x8e58c, y=(rtx) 0x1086c4) \
-(/gp/rms/cc/rtlanal.c line 337)
-#1 0x246b0 in expand_call (...) (...)
-#2 0x21cfc in expand_expr (...) (...)
+@smallexample
+@group
+#0 m4_traceon (obs=0x24eb0, argc=1, argv=0x2b8c8)
+ at builtin.c:993
+#1 0x6e38 in expand_macro (sym=0x2b600) at macro.c:242
+#2 0x6840 in expand_token (obs=0x0, t=177664, td=0xf7fffb08)
+ at macro.c:71
(More stack frames follow...)
-@end example
+@end group
+@end smallexample
@noindent
-The functions @code{expand_call} and @code{expand_expr} are in a file
-whose symbol details have not been fully read. Full detail is available
-for the function @code{rtx_equal_p}, which is in the file
-@file{rtlanal.c}. Its arguments, named @code{x} and @code{y}, are shown
-with their typed values.
+The display for frame zero does not begin with a program counter
+value, indicating that your program has stopped at the beginning of the
+code for line @code{993} of @code{builtin.c}.
@node Selection, Frame Info, Backtrace, Stack
@section Selecting a Frame
-Most commands for examining the stack and other data in the program work on
+Most commands for examining the stack and other data in your program work on
whichever stack frame is selected at the moment. Here are the commands for
selecting a stack frame; all of them finish by printing a brief description
of the stack frame just selected.
@table @code
@item frame @var{n}
+@itemx f @var{n}
@kindex frame
+@kindex f
Select frame number @var{n}. Recall that frame zero is the innermost
(currently executing) frame, frame one is the frame that called the
innermost one, and so on. The highest-numbered frame is @code{main}'s
frame.
@item frame @var{addr}
+@itemx f @var{addr}
Select the frame at address @var{addr}. This is useful mainly if the
chaining of stack frames has been damaged by a bug, making it
impossible for _GDBN__ to assign numbers properly to all frames. In
-addition, this can be useful when the program has multiple stacks and
+addition, this can be useful when your program has multiple stacks and
switches between them.
+_if__(_SPARC__)
+On the SPARC architecture, @code{frame} needs two addresses to
+select an arbitrary frame: a frame pointer and a stack pointer.
+@c note to future updaters: this is conditioned on a flag
+@c FRAME_SPECIFICATION_DYADIC in the tm-*.h files, currently only used
+@c by SPARC, hence the specific attribution. Generalize or list all
+@c possibilities if more supported machines start doing this.
+_fi__(_SPARC__)
+
@item up @var{n}
@kindex up
-Select the frame @var{n} frames up from the frame previously selected.
-For positive numbers @var{n}, this advances toward the outermost
-frame, to higher frame numbers, to frames that have existed longer.
-@var{n} defaults to one.
+Move @var{n} frames up the stack. For positive numbers @var{n}, this
+advances toward the outermost frame, to higher frame numbers, to frames
+that have existed longer. @var{n} defaults to one.
@item down @var{n}
@kindex down
-Select the frame @var{n} frames down from the frame previously
-selected. For positive numbers @var{n}, this advances toward the
-innermost frame, to lower frame numbers, to frames that were created
-more recently. @var{n} defaults to one.
+@kindex do
+Move @var{n} frames down the stack. For positive numbers @var{n}, this
+advances toward the innermost frame, to lower frame numbers, to frames
+that were created more recently. @var{n} defaults to one. You may
+abbreviate @code{down} as @code{do}.
@end table
-All of these commands end by printing some information on the frame that
-has been selected: the frame number, the function name, the arguments, the
-source file and line number of execution in that frame, and the text of
-that source line. For example:
+All of these commands end by printing two lines of output describing the
+frame. The first line shows the frame number, the function name, the
+arguments, and the source file and line number of execution in that
+frame. The second line shows the text of that source line. For
+example:
-@example
-#3 main (argc=3, argv=??, env=??) at main.c:67
-67 read_input_file (argv[i]);
-@end example
+@smallexample
+@group
+(_GDBP__) up
+#1 0x22f0 in main (argc=1, argv=0xf7fffbf4, env=0xf7fffbfc)
+ at env.c:10
+10 read_input_file (argv[i]);
+@end group
+@end smallexample
-After such a printout, the @samp{list} command with no arguments will print
-ten lines centered on the point of execution in the frame. @xref{List}.
+After such a printout, the @code{list} command with no arguments will
+print ten lines centered on the point of execution in the frame.
+@xref{List, ,Printing Source Lines}.
@table @code
@item up-silently @var{n}
@itemx down-silently @var{n}
@kindex down-silently
@kindex up-silently
-These two commands are variants of @samp{up} and @samp{down},
+These two commands are variants of @code{up} and @code{down},
respectively; they differ in that they do their work silently, without
causing display of the new frame. They are intended primarily for use
in _GDBN__ command scripts, where the output might be unnecessary and
-distracting.
-
+distracting.
@end table
@node Frame Info, , Selection, Stack
-@section Information on a Frame
+@section Information About a Frame
There are several other commands to print information about the selected
stack frame.
@table @code
@item frame
-When used without any argument, this command does not change which frame
-is selected, but still prints a brief description of the currently
-selected stack frame. It can be abbreviated @samp{f}. With an
-argument, this command is used to select a stack frame; with no
-argument, it does not change which frame is selected, but still prints
-the same kind of information.
+@itemx f
+When used without any argument, this command does not change which
+frame is selected, but prints a brief description of the currently
+selected stack frame. It can be abbreviated @code{f}. With an
+argument, this command is used to select a stack frame
+(@pxref{Selection, ,Selecting a Frame}).
@item info frame
+@itemx info f
@kindex info frame
+@kindex info f
This command prints a verbose description of the selected stack frame,
-including the address of the frame, the addresses of the next frame in
-(called by this frame) and the next frame out (caller of this frame),
+including the address of the frame, the addresses of the next frame down
+(called by this frame) and the next frame up (caller of this frame), the
+language that the source code corresponding to this frame was written in,
the address of the frame's arguments, the program counter saved in it
(the address of execution in the caller frame), and which registers
were saved in the frame. The verbose description is useful when
the usual conventions.
@item info frame @var{addr}
+@itemx info f @var{addr}
Print a verbose description of the frame at address @var{addr},
without selecting that frame. The selected frame remains unchanged by
this command.
@cindex catch exceptions
@cindex exception handlers
Print a list of all the exception handlers that are active in the
-current stack frame given the current value of @code{pc}. To see other
-exception handlers, visit the associated frame (using the @samp{up},
-@samp{down}, or @samp{frame} commands); then type @samp{info catch}.
-@xref{Exception Handling}.
+current stack frame at the current point of execution. To see other
+exception handlers, visit the associated frame (using the @code{up},
+@code{down}, or @code{frame} commands); then type @code{info catch}.
+@xref{Exception Handling, ,Breakpoints and Exceptions}.
@end table
@node Source, Data, Stack, Top
@chapter Examining Source Files
-_GDBN__ knows which source files your program was compiled from, and
-can print parts of their text. When your program stops, _GDBN__
-spontaneously prints the line it stopped in. Likewise, when you
-select a stack frame (@pxref{Selection}), _GDBN__ prints the line
-which execution in that frame has stopped in. You can also
-print parts of source files by explicit command.
+_GDBN__ can print parts of your program's source, since the debugging
+information recorded in your program tells _GDBN__ what source files were
+used to build it. When your program stops, _GDBN__ spontaneously prints
+the line where it stopped. Likewise, when you select a stack frame
+(@pxref{Selection, ,Selecting a Frame}), _GDBN__ prints the line where
+execution in that frame has stopped. You can print other portions of
+source files by explicit command.
+
+If you use _GDBN__ through its GNU Emacs interface, you may prefer to use
+Emacs facilities to view source; @pxref{Emacs, ,Using _GDBN__ under GNU
+Emacs}.
@menu
-* List:: Using the @samp{list} command to print source files.
-* Search:: Commands for searching source files.
-* Source Path:: Specifying the directories to search for source files.
+* List:: Printing Source Lines
+* Search:: Searching Source Files
+* Source Path:: Specifying Source Directories
+* Machine Code:: Source and Machine Code
@end menu
@node List, Search, Source, Source
@kindex list
@kindex l
-To print lines from a source file, use the @samp{list} command
-(abbreviated @samp{l}). There are several ways to specify what part
+To print lines from a source file, use the @code{list} command
+(abbreviated @code{l}). There are several ways to specify what part
of the file you want to print.
-Here are the forms of the @samp{list} command most commonly used:
+Here are the forms of the @code{list} command most commonly used:
@table @code
@item list @var{linenum}
-Print ten lines centered around line number @var{linenum} in the
+Print lines centered around line number @var{linenum} in the
current source file.
@item list @var{function}
-Print ten lines centered around the beginning of function
+Print lines centered around the beginning of function
@var{function}.
@item list
-Print ten more lines. If the last lines printed were printed with a
-@samp{list} command, this prints ten lines following the last lines
+Print more lines. If the last lines printed were printed with a
+@code{list} command, this prints lines following the last lines
printed; however, if the last line printed was a solitary line printed
-as part of displaying a stack frame (@pxref{Stack}), this prints ten
-lines centered around that line.
+as part of displaying a stack frame (@pxref{Stack, ,Examining the
+Stack}), this prints lines centered around that line.
@item list -
-Print ten lines just before the lines last printed.
+Print lines just before the lines last printed.
+@end table
+
+By default, _GDBN__ prints ten source lines with any of these forms of
+the @code{list} command. You can change this using @code{set listsize}:
+
+@table @code
+@item set listsize @var{count}
+@kindex set listsize
+Make the @code{list} command display @var{count} source lines (unless
+the @code{list} argument explicitly specifies some other number).
+
+@item show listsize
+@kindex show listsize
+Display the number of lines that @code{list} will currently display by
+default.
@end table
-Repeating a @samp{list} command with @key{RET} discards the argument,
-so it is equivalent to typing just @samp{list}. This is more useful
+Repeating a @code{list} command with @key{RET} discards the argument,
+so it is equivalent to typing just @code{list}. This is more useful
than listing the same lines again. An exception is made for an
argument of @samp{-}; that argument is preserved in repetition so that
-each repetition moves up in the file.
+each repetition moves up in the source file.
@cindex linespec
-In general, the @samp{list} command expects you to supply zero, one or two
+In general, the @code{list} command expects you to supply zero, one or two
@dfn{linespecs}. Linespecs specify source lines; there are several ways
of writing them but the effect is always to specify some source line.
-Here is a complete description of the possible arguments for @samp{list}:
+Here is a complete description of the possible arguments for @code{list}:
@table @code
@item list @var{linespec}
-Print ten lines centered around the line specified by @var{linespec}.
+Print lines centered around the line specified by @var{linespec}.
@item list @var{first},@var{last}
Print lines from @var{first} to @var{last}. Both arguments are
linespecs.
@item list ,@var{last}
-Print ten lines ending with @var{last}.
+Print lines ending with @var{last}.
@item list @var{first},
-Print ten lines starting with @var{first}.
+Print lines starting with @var{first}.
@item list +
-Print ten lines just after the lines last printed.
+Print lines just after the lines last printed.
@item list -
-Print ten lines just before the lines last printed.
+Print lines just before the lines last printed.
@item list
As described in the preceding table.
kinds of linespec.
@table @code
-@item @var{linenum}
-Specifies line @var{linenum} of the current source file.
-When a @samp{list} command has two linespecs, this refers to
+@item @var{number}
+Specifies line @var{number} of the current source file.
+When a @code{list} command has two linespecs, this refers to
the same source file as the first linespec.
@item +@var{offset}
Specifies the line @var{offset} lines after the last line printed.
-When used as the second linespec in a @samp{list} command that has
+When used as the second linespec in a @code{list} command that has
two, this specifies the line @var{offset} lines down from the
first linespec.
@item -@var{offset}
Specifies the line @var{offset} lines before the last line printed.
-@item @var{filename}:@var{linenum}
-Specifies line @var{linenum} in the source file @var{filename}.
+@item @var{filename}:@var{number}
+Specifies line @var{number} in the source file @var{filename}.
@item @var{function}
+@c FIXME: "of the open-brace" is C-centric. When we add other langs...
Specifies the line of the open-brace that begins the body of the
function @var{function}.
@item @var{filename}:@var{function}
Specifies the line of the open-brace that begins the body of the
-function @var{function} in the file @var{filename}. The file name is
-needed with a function name only for disambiguation of identically
-named functions in different source files.
+function @var{function} in the file @var{filename}. You only need the
+file name with a function name to avoid ambiguity when there are
+identically named functions in different source files.
@item *@var{address}
Specifies the line containing the program address @var{address}.
@var{address} may be any expression.
@end table
-One other command is used to map source lines to program addresses.
-
-@table @code
-@item info line @var{linenum}
-@kindex info line
-Print the starting and ending addresses of the compiled code for
-source line @var{linenum}.
-
-@kindex $_
-The default examine address for the @samp{x} command is changed to the
-starting address of the line, so that @samp{x/i} is sufficient to
-begin examining the machine code (@pxref{Memory}). Also, this address
-is saved as the value of the convenience variable @code{$_}
-(@pxref{Convenience Vars}).
-@end table
-
@node Search, Source Path, List, Source
@section Searching Source Files
@cindex searching
-@kindex search
-@kindex forward-search
@kindex reverse-search
There are two commands for searching through the current source file for a
regular expression.
-The command @samp{forward-search @var{regexp}} checks each line, starting
-with the one following the last line listed, for a match for @var{regexp}.
-It lists the line that is found. You can abbreviate the command name
-as @samp{fo}. The synonym @samp{search @var{regexp}} is also supported.
+@table @code
+@item forward-search @var{regexp}
+@itemx search @var{regexp}
+@kindex search
+@kindex forward-search
+The command @samp{forward-search @var{regexp}} checks each line,
+starting with the one following the last line listed, for a match for
+@var{regexp}. It lists the line that is found. You can use
+synonym @samp{search @var{regexp}} or abbreviate the command name as
+@code{fo}.
+@item reverse-search @var{regexp}
The command @samp{reverse-search @var{regexp}} checks each line, starting
with the one before the last line listed and going backward, for a match
for @var{regexp}. It lists the line that is found. You can abbreviate
-this command with as little as @samp{rev}.
+this command as @code{rev}.
+@end table
-@node Source Path, , Search, Source
+@node Source Path, Machine Code, Search, Source
@section Specifying Source Directories
@cindex source path
Executable programs sometimes do not record the directories of the source
files from which they were compiled, just the names. Even when they do,
the directories could be moved between the compilation and your debugging
-session. _GDBN__ remembers a list of directories to search for source files;
+session. _GDBN__ has a list of directories to search for source files;
this is called the @dfn{source path}. Each time _GDBN__ wants a source file,
it tries all the directories in the list, in the order they are present
in the list, until it finds a file with the desired name. Note that
the current working directory, unless it happens to be in the source
path.
-If it can't find a source file in the source path, and the object program
-records what directory it was compiled in, _GDBN__ tries that directory too.
-If the source path is empty, and there is no record of the compilation
-directory, _GDBN__ will, as a last resort, look in the current directory.
+If _GDBN__ cannot find a source file in the source path, and the object
+program records a directory, _GDBN__ tries that directory too. If the
+source path is empty, and there is no record of the compilation
+directory, _GDBN__ will, as a last resort, look in the current
+directory.
Whenever you reset or rearrange the source path, _GDBN__ will clear out
any information it has cached about where source files are found, where
@kindex directory
When you start _GDBN__, its source path is empty.
-To add other directories, use the @samp{directory} command.
+To add other directories, use the @code{directory} command.
@table @code
-@item directory @var{dirnames...}
+@item directory @var{dirname} @dots{}
Add directory @var{dirname} to the front of the source path. Several
-directory names may be given to this command, separated by whitespace or
-@samp{:}. If a name is already in the source path, it is moved to the
-front of the path, so it will be searched sooner.
+directory names may be given to this command, separated by @samp{:} or
+whitespace. You may specify a directory that is already in the source
+path; this moves it forward, so it will be searched sooner.
+
+You can use the string @samp{$cdir} to refer to the compilation
+directory (if one is recorded), and @samp{$cwd} to refer to the current
+working directory. @samp{$cwd} is not the same as @samp{.}---the former
+tracks the current working directory as it changes during your _GDBN__
+session, while the latter is immediately expanded to the current
+directory at the time you add an entry to the source path.
@item directory
Reset the source path to empty again. This requires confirmation.
-@item info directories
-@kindex info directories
+@c RET-repeat for @code{directory} is explicitly disabled, but since
+@c repeating it would be a no-op we do not say that. (thanks to RMS)
+
+@item show directories
+@kindex show directories
Print the source path: show which directories it contains.
@end table
-Because the @samp{directory} command, when used with arguments, adds to
-the front of the source path, it can affect files that _GDBN__ has already
-found. If the source path contains directories that you do not want,
-and these directories contain misleading files with names matching your
-source files, the way to correct the situation is as follows:
+If your source path is cluttered with directories that are no longer of
+interest, _GDBN__ may sometimes cause confusion by finding the wrong
+versions of source. You can correct the situation as follows:
@enumerate
@item
-Use @samp{directory} with no argument to reset the source path to empty.
+Use @code{directory} with no argument to reset the source path to empty.
@item
-Use @samp{directory} with suitable arguments to add any other
-directories you want in the source path. You can add all the directories
-in one command.
+Use @code{directory} with suitable arguments to reinstall the
+directories you want in the source path. You can add all the
+directories in one command.
@end enumerate
-@node Data, Symbols, Source, Top
-@chapter Examining Data
+@node Machine Code, , Source Path, Source
+@section Source and Machine Code
-@cindex printing data
-@cindex examining data
-@kindex print
-@kindex inspect
-The usual way to examine data in your program is with the @samp{print}
-command (abbreviated @samp{p}), or its synonym @samp{inspect}. It
-evaluates and prints the value of any valid expression of the language
-the program is written in (for now, C or C++). You type
+You can use the command @code{info line} to map source lines to program
+addresses (and viceversa), and the command @code{disassemble} to display
+a range of addresses as machine instructions.
-@example
-print @var{exp}
-@end example
+@table @code
+@item info line @var{linespec}
+@kindex info line
+Print the starting and ending addresses of the compiled code for
+source line @var{linespec}. You can specify source lines in any of
+the ways understood by the @code{list} command (@pxref{List, ,Printing
+Source Lines}).
+@end table
+
+For example, we can use @code{info line} to discover the location of
+the object code for the first line of function
+@code{m4_changequote}:
+
+@smallexample
+(_GDBP__) info line m4_changecom
+Line 895 of "builtin.c" starts at pc 0x634c and ends at 0x6350.
+@end smallexample
@noindent
-where @var{exp} is any valid expression (in the source language), and
-the value of @var{exp} is printed in a format appropriate to its data
-type.
+We can also inquire (using @code{*@var{addr}} as the form for
+@var{linespec}) what source line covers a particular address:
+@smallexample
+(_GDBP__) info line *0x63ff
+Line 926 of "builtin.c" starts at pc 0x63e4 and ends at 0x6404.
+@end smallexample
-A more low-level way of examining data is with the @samp{x} command.
-It examines data in memory at a specified address and prints it in a
-specified format.
+@cindex @code{$_} and @code{info line}
+After @code{info line}, the default address for the @code{x} command
+is changed to the starting address of the line, so that @samp{x/i} is
+sufficient to begin examining the machine code (@pxref{Memory,
+,Examining Memory}). Also, this address is saved as the value of the
+convenience variable @code{$_} (@pxref{Convenience Vars, ,Convenience
+Variables}).
-@menu
-* Expressions:: Expressions that can be computed and printed.
-* Variables:: Using your program's variables in expressions.
-* Arrays:: Examining part of memory as an array.
-* Format options:: Controlling how structures and arrays are printed.
-* Output formats:: Specifying formats for printing values.
-* Auto Display:: Printing certain expressions whenever program stops.
-* Value History:: Referring to values previously printed.
-* Convenience Vars:: Giving names to values for future reference.
-* Registers:: Referring to and storing in machine registers.
+@table @code
+@kindex disassemble
+@item disassemble
+This specialized command dumps a range of memory as machine
+instructions. The default memory range is the function surrounding the
+program counter of the selected frame. A single argument to this
+command is a program counter value; the function surrounding this value
+will be dumped. Two arguments specify a range of addresses (first
+inclusive, second exclusive) to dump.
+@end table
+
+We can use @code{disassemble} to inspect the object code
+range shown in the last @code{info line} example:
+
+@smallexample
+(_GDBP__) disas 0x63e4 0x6404
+Dump of assembler code from 0x63e4 to 0x6404:
+0x63e4 <builtin_init+5340>: ble 0x63f8 <builtin_init+5360>
+0x63e8 <builtin_init+5344>: sethi %hi(0x4c00), %o0
+0x63ec <builtin_init+5348>: ld [%i1+4], %o0
+0x63f0 <builtin_init+5352>: b 0x63fc <builtin_init+5364>
+0x63f4 <builtin_init+5356>: ld [%o0+4], %o0
+0x63f8 <builtin_init+5360>: or %o0, 0x1a4, %o0
+0x63fc <builtin_init+5364>: call 0x9288 <path_search>
+0x6400 <builtin_init+5368>: nop
+End of assembler dump.
+@end smallexample
+
+@node Data, Languages, Source, Top
+@chapter Examining Data
+
+@cindex printing data
+@cindex examining data
+@kindex print
+@kindex inspect
+@c "inspect" is not quite a synonym if you are using Epoch, which we do not
+@c document because it is nonstandard... Under Epoch it displays in a
+@c different window or something like that.
+The usual way to examine data in your program is with the @code{print}
+command (abbreviated @code{p}), or its synonym @code{inspect}. It
+evaluates and prints the value of an expression of the language your
+program is written in (@pxref{Languages, ,Using _GDBN__ with Different
+Languages}).
+
+@table @code
+@item print @var{exp}
+@itemx print /@var{f} @var{exp}
+@var{exp} is an expression (in the source language). By default
+the value of @var{exp} is printed in a format appropriate to its data
+type; you can choose a different format by specifying @samp{/@var{f}},
+where @var{f} is a letter specifying the format; @pxref{Output formats}.
+
+@item print
+@itemx print /@var{f}
+If you omit @var{exp}, _GDBN__ displays the last value again (from the
+@dfn{value history}; @pxref{Value History, ,Value History}). This allows you to
+conveniently inspect the same value in an alternative format.
+@end table
+
+A more low-level way of examining data is with the @code{x} command.
+It examines data in memory at a specified address and prints it in a
+specified format. @xref{Memory, ,Examining Memory}.
+
+If you are interested in information about types, or about how the fields
+of a struct or class are declared, use the @code{ptype @var{exp}}
+command rather than @code{print}. @xref{Symbols, ,Examining the Symbol Table}.
+
+@menu
+* Expressions:: Expressions
+* Variables:: Program Variables
+* Arrays:: Artificial Arrays
+* Output formats:: Output formats
+* Memory:: Examining Memory
+* Auto Display:: Automatic Display
+* Print Settings:: Print Settings
+* Value History:: Value History
+* Convenience Vars:: Convenience Variables
+* Registers:: Registers
+* Floating Point Hardware:: Floating Point Hardware
@end menu
@node Expressions, Variables, Data, Data
@section Expressions
@cindex expressions
-Many different _GDBN__ commands accept an expression and compute its value.
-Any kind of constant, variable or operator defined by the programming
-language you are using is legal in an expression in _GDBN__. This includes
-conditional expressions, function calls, casts and string constants. It
-unfortunately does not include symbols defined by preprocessor
-@code{#define} commands, or C++ expressions involving @samp{::}, the
-name resolution operator.
+@code{print} and many other _GDBN__ commands accept an expression and
+compute its value. Any kind of constant, variable or operator defined
+by the programming language you are using is legal in an expression in
+_GDBN__. This includes conditional expressions, function calls, casts
+and string constants. It unfortunately does not include symbols defined
+by preprocessor @code{#define} commands.
+
+Because C is so widespread, most of the expressions shown in examples in
+this manual are in C. @xref{Languages, , Using _GDBN__ with Different
+Languages}, for information on how to use expressions in other
+languages.
+
+In this section, we discuss operators that you can use in _GDBN__
+expressions regardless of your programming language.
Casts are supported in all languages, not just in C, because it is so
useful to cast a number into a pointer so as to examine a structure
at that address in memory.
+@c FIXME: casts supported---Mod2 true?
-_GDBN__ supports three kinds of operator in addition to those of programming
+_GDBN__ supports these operators in addition to those of programming
languages:
@table @code
@item @@
@samp{@@} is a binary operator for treating parts of memory as arrays.
-@xref{Arrays}, for more information.
+@xref{Arrays, ,Artificial Arrays}, for more information.
@item ::
@samp{::} allows you to specify a variable in terms of the file or
-function it is defined in. @xref{Variables}.
+function where it is defined. @xref{Variables, ,Program Variables}.
@item @{@var{type}@} @var{addr}
Refers to an object of type @var{type} stored at address @var{addr} in
memory. @var{addr} may be any expression whose value is an integer or
-pointer (but parentheses are required around nonunary operators, just as in
+pointer (but parentheses are required around binary operators, just as in
a cast). This construct is allowed regardless of what kind of data is
-officially supposed to reside at @var{addr}.@refill
+normally supposed to reside at @var{addr}.
@end table
@node Variables, Arrays, Expressions, Data
in your program.
Variables in expressions are understood in the selected stack frame
-(@pxref{Selection}); they must either be global (or static) or be visible
-according to the scope rules of the programming language from the point of
-execution in that frame. This means that in the function
+(@pxref{Selection, ,Selecting a Frame}); they must either be global
+(or static) or be visible according to the scope rules of the
+programming language from the point of execution in that frame. This
+means that in the function
@example
foo (a)
@end example
@noindent
-the variable @code{a} is usable whenever the program is executing
+the variable @code{a} is usable whenever your program is executing
within the function @code{foo}, but the variable @code{b} is visible
-only while the program is executing inside the block in which @code{b}
+only while your program is executing inside the block in which @code{b}
is declared.
-As a special exception, you can refer to a variable or function whose
+@cindex variable name conflict
+There is an exception: you can refer to a variable or function whose
scope is a single source file even if the current execution point is not
-in this file. But it is possible to have more than one such variable
-or function with the same name (if they are in different source files).
-In such a case, it is not defined which one you will get. If you wish,
-you can specify any one of them using the colon-colon construct:
+in this file. But it is possible to have more than one such variable or
+function with the same name (in different source files). If that
+happens, referring to that name has unpredictable effects. If you wish,
+you can specify a static variable in a particular function or file,
+using the colon-colon notation:
@cindex colon-colon
-@cindex scope
+@iftex
+@c info cannot cope with a :: index entry, but why deprive hard copy readers?
@kindex ::
+@end iftex
@example
-@var{block}::@var{variable}
+@var{file}::@var{variable}
+@var{function}::@var{variable}
@end example
@noindent
-Here @var{block} is the name of the source file whose variable you want.
+Here @var{file} or @var{function} is the name of the context for the
+static @var{variable}.
+
+@cindex C++ scope resolution
+This use of @samp{::} is very rarely in conflict with the very similar
+use of the same notation in C++. _GDBN__ also supports use of the C++
+scope resolution operator in _GDBN__ expressions.
-@cindex name resolution (C++)
-Unfortunately, this use of @samp{::} conflicts with the very similar use
-of the same notation in C++; accordingly, _GDBN__ does not support use of
-the C++ name resolution operator in _GDBN__ expressions.
+@cindex wrong values
+@cindex variable values, wrong
+@quotation
+@emph{Warning:} Occasionally, a local variable may appear to have the
+wrong value at certain points in a function---just after entry to the
+function, and just before exit. You may see this problem when you are
+stepping by machine instructions. This is because on most machines, it
+takes more than one instruction to set up a stack frame (including local
+variable definitions); if you are stepping by machine instructions,
+variables may appear to have the wrong values until the stack frame is
+completely built. On function exit, it usually also takes more than one
+machine instruction to destroy a stack frame; after you begin stepping
+through that group of instructions, local variable definitions may be
+gone.
+@end quotation
-@node Arrays, Format options, Variables, Data
+@node Arrays, Output formats, Variables, Data
@section Artificial Arrays
@cindex artificial array
This can be done by constructing an @dfn{artificial array} with the
binary operator @samp{@@}. The left operand of @samp{@@} should be
the first element of the desired array, as an individual object.
-The right operand should be the length of the array. The result is
+The right operand should be the desired length of the array. The result is
an array value whose elements are all of the type of the left argument.
The first element is actually the left argument; the second element
comes from bytes of memory immediately following those that hold the
The left operand of @samp{@@} must reside in memory. Array values made
with @samp{@@} in this way behave just like other arrays in terms of
subscripting, and are coerced to pointers when used in expressions.
-(It would probably appear in an expression via the value history,
-after you had printed it out.)
-
-@node Format options, Output formats, Arrays, Data
-@section Format options
-
-@cindex format options
-_GDBN__ provides a few ways to control how arrays, structures, and symbols are
-printed.
-
-@table @code
-@item set array-max @var{number-of-elements}
-@kindex set array-max
-If _GDBN__ is printing a large array, it will stop printing after it has
-printed the number of elements set by the @samp{set array-max} command.
-This limit also applies to the display of strings.
-
-@item show array-max
-@kindex show array-max
-Display the number of elements of a large array that _GDBN__ will print
-before losing patience.
-
-@item set arrayprint
-@itemx set arrayprint on
-@kindex set arrayprint
-_GDBN__ will pretty print arrays. This format is more convenient to read,
-but uses more space. The default is off.
-
-@item set arrayprint off.
-Return to compressed format for arrays.
-
-@item show arrayprint
-@kindex show arrayprint
-Show whether compressed or pretty format is selected for displaying
-arrays.
-
-@item set demangle
-@itemx set demangle on
-@kindex set demangle
-Print C++ names in their source form rather than in the mangled form
-in which they are passed to the assembler and linker for type-safe linkage.
-The default is on.
-
-@item show demangle
-@kindex show demangle
-Show whether C++ names will be printed in mangled or demangled form.
-
-@item set asm-demangle
-@itemx set asm-demangle on
-@kindex set asm-demangle
-Print C++ names in their source form rather than their mangled form, even
-in assembler code printouts such as instruction disassemblies.
-The default is off.
-
-@item show asm-demangle
-@kindex show asm-demangle
-Show whether C++ names in assembly listings will be printed in mangled
-or demangled form.
-
-@item set vtblprint
-@itemx set vtblprint on
-@kindex set vtblprint
-Pretty print C++ virtual function tables. The default is off.
-
-@item set vtblprint off
-Do not pretty print C++ virtual function tables.
-
-@item show vtblprint
-@kindex show vtblprint
-Show whether C++ virtual function tables are pretty printed, or not.
-
-@item set addressprint
-@item set addressprint on
-@kindex set addressprint
-_GDBN__ will print memory addresses in stack traces, structure values, pointer
-values, breakpoints, etc. The default is on.
-
-@item set addressprint off
-Do not print addresses.
-
-@item show addressprint
-@kindex show addressprint
-Show whether or not addresses are to be printed.
-
-@item set prettyprint on
-@kindex set prettyprint
-Cause _GDBN__ to print structures in an indented format with one member per
-line, like this:
-
-@example
-$1 = @{
- next = 0x0,
- flags = @{
- sweet = 1,
- sour = 1
- @},
- meat = 0x54 "Pork"
-@}
-@end example
-
-@item set prettyprint off
-Cause _GDBN__ to print structures in a compact format, like this:
-
-@smallexample
-$1 = @{next = 0x0, flags = @{sweet = 1, sour = 1@}, meat \
-= 0x54 "Pork"@}
-@end smallexample
-
-@noindent
-This is the default format.
-
-@item show prettyprint
-@kindex show prettyprint
-Show which format _GDBN__ will use to print structures.
-
-@item set unionprint on
-@kindex set unionprint
-Tell _GDBN__ to print unions which are contained in structures. This is the
-default setting.
-
-@item set unionprint off
-Tell _GDBN__ not to print unions which are contained in structures.
-
-@item show unionprint
-@kindex show unionprint
-Ask _GDBN__ whether or not it will print unions which are contained in
-structures.
-
-For example, given the declarations
-
-@smallexample
-typedef enum @{Tree, Bug@} Species;
-typedef enum @{Big_tree, Acorn, Seedling@} Tree_forms;
-typedef enum @{Caterpillar, Cocoon, Butterfly@} Bug_forms;
-
-struct thing @{
- Species it;
- union @{
- Tree_forms tree;
- Bug_forms bug;
- @} form;
-@};
-
-struct thing foo = @{Tree, @{Acorn@}@};
-@end smallexample
-
-@noindent
-with @samp{set unionprint on} in effect @samp{p foo} would print
-
-@smallexample
-$1 = @{it = Tree, form = @{tree = Acorn, bug = Cocoon@}@}
-@end smallexample
-
-@noindent
-and with @samp{set unionprint off} in effect it would print
+Artificial arrays most often appear in expressions via the value history
+(@pxref{Value History, ,Value History}), after printing one out.)
+
+Sometimes the artificial array mechanism is not quite enough; in
+moderately complex data structures, the elements of interest may not
+actually be adjacent---for example, if you are interested in the values
+of pointers in an array. One useful work-around in this situation is
+to use a convenience variable (@pxref{Convenience Vars, ,Convenience
+Variables}) as a counter in an expression that prints the first
+interesting value, and then repeat that expression via @key{RET}. For
+instance, suppose you have an array @code{dtab} of pointers to
+structures, and you are interested in the values of a field @code{fv}
+in each structure. Here is an example of what you might type:
@example
-$1 = @{it = Tree, form = @{...@}@}
+set $i = 0
+p dtab[$i++]->fv
+@key{RET}
+@key{RET}
+@dots{}
@end example
-@end table
-@node Output formats, Auto Display, Format options, Data
+@node Output formats, Memory, Arrays, Data
@section Output formats
@cindex formatted output
@cindex output formats
-_GDBN__ normally prints all values according to their data types. Sometimes
+By default, _GDBN__ prints a value according to its data type. Sometimes
this is not what you want. For example, you might want to print a number
in hex, or a pointer in decimal. Or you might want to view data in memory
-at a certain address as a character string or an instruction. These things
-can be done with @dfn{output formats}.
+at a certain address as a character string or as an instruction. To do
+these things, specify an @dfn{output format} when you print a value.
The simplest use of output formats is to say how to print a value
already computed. This is done by starting the arguments of the
-@samp{print} command with a slash and a format letter. The format
+@code{print} command with a slash and a format letter. The format
letters supported are:
-@table @samp
+@table @code
@item x
Regard the bits of the value as an integer, and print the integer in
hexadecimal.
@item o
Print as integer in octal.
+@item t
+Print as integer in binary. The letter @samp{t} stands for ``two''.
+
@item a
Print as an address, both absolute in hex and as an offset from the
nearest preceding symbol. This format can be used to discover where (in
what function) an unknown address is located:
+
@example
(_GDBP__) p/a 0x54320
-$3 = 0x54320 <_initialize_vx+396>
+_0__$3 = 0x54320 <_initialize_vx+396>_1__
@end example
-
@item c
Regard as an integer and print it as a character constant.
names in _GDBN__ cannot contain a slash.
To reprint the last value in the value history with a different format,
-you can use the @samp{print} command with just a format and no
+you can use the @code{print} command with just a format and no
expression. For example, @samp{p/x} reprints the last value in hex.
-@menu
-* Memory:: Examining Memory
-@end menu
+@node Memory, Auto Display, Output formats, Data
+@section Examining Memory
-@node Memory, , Output formats, Output formats
-@subsection Examining Memory
+You can use the command @code{x} (for ``examine'') to examine memory in
+any of several formats, independently of your program's data types.
@cindex examining memory
@table @code
-@kindex disassemble
-@item disassemble
-This specialized command is provided to dump a range of memory as
-machine instructions. The default memory range is the function
-surrounding the program counter of the selected frame. A single
-argument to this command is a program counter value; the function
-surrounding this value will be dumped. Two arguments (separated by one
-or more spaces) specify a range of addresses (first inclusive, second
-exclusive) to be dumped.
-
@kindex x
-@item x
-The command @samp{x} (for `examine') can be used to examine memory
-without reference to the program's data types. The format in which you
-wish to examine memory is instead explicitly specified. The allowable
-formats are a superset of the formats described in the previous section.
+@item x/@var{nfu} @var{addr}
+@itemx x @var{addr}
+@itemx x
+Use the command @code{x} to examine memory.
@end table
-@samp{x} is followed by a slash and an output format specification,
-followed by an expression for an address. The expression need not have
-a pointer value (though it may); it is used as an integer, as the
-address of a byte of memory. @xref{Expressions} for more information on
-expressions. For example, @samp{x/4xw $sp} prints the four words of
-memory above the stack pointer in hexadecimal.
-
-The output format in this case specifies both how big a unit of memory
-to examine and how to print the contents of that unit. It is done
-with one or two of the following letters:
-
-These letters specify just the size of unit to examine:
-
-@table @samp
+@var{n}, @var{f}, and @var{u} are all optional parameters that specify how
+much memory to display and how to format it; @var{addr} is an
+expression giving the address where you want to start displaying memory.
+If you use defaults for @var{nfu}, you need not type the slash @samp{/}.
+Several commands set convenient defaults for @var{addr}.
+
+@table @r
+@item @var{n}, the repeat count
+The repeat count is a decimal integer; the default is 1. It specifies
+how much memory (counting by units @var{u}) to display.
+@c This really is **decimal**; unaffected by 'set radix' as of GDB
+@c 4.1.2.
+
+@item @var{f}, the display format
+The display format is one of the formats used by @code{print},
+or @samp{s} (null-terminated string) or @samp{i} (machine instruction).
+The default is @samp{x} (hexadecimal) initially, or the format from the
+last time you used either @code{x} or @code{print}.
+
+@item @var{u}, the unit size
+The unit size is any of
+@table @code
@item b
-Examine individual bytes.
-
+Bytes.
@item h
-Examine halfwords (two bytes each).
-
+Halfwords (two bytes).
@item w
-Examine words (four bytes each).
-
-@cindex word
-Many assemblers and cpu designers still use `word' for a 16-bit quantity,
-as a holdover from specific predecessor machines of the 1970's that really
-did use two-byte words. But more generally the term `word' has always
-referred to the size of quantity that a machine normally operates on and
-stores in its registers. This is 32 bits for all the machines that _GDBN__
-runs on.
-
+Words (four bytes). This is the initial default.
@item g
-Examine giant words (8 bytes).
+Giant words (eight bytes).
@end table
-These letters specify just the way to print the contents:
-
-@table @samp
-@item x
-Print as integers in unsigned hexadecimal.
-
-@item d
-Print as integers in signed decimal.
-
-@item u
-Print as integers in unsigned decimal.
-
-@item o
-Print as integers in unsigned octal.
-
-@item a
-Print as an address, both absolute in hex and then relative
-to a symbol defined as an address below it.
-
-@item c
-Print as character constants.
-
-@item f
-Print as floating point. This works only with sizes @samp{w} and
-@samp{g}.
-
-@item s
-Print a null-terminated string of characters. The specified unit size
-is ignored; instead, the unit is however many bytes it takes to reach
-a null character (including the null character).
-
-@item i
-Print a machine instruction in assembler syntax (or nearly). The
-specified unit size is ignored; the number of bytes in an instruction
-varies depending on the type of machine, the opcode and the addressing
-modes used. The command @samp{disassemble} gives an alternative way of
-inspecting machine instructions.
+Each time you specify a unit size with @code{x}, that size becomes the
+default unit the next time you use @code{x}. (For the @samp{s} and
+@samp{i} formats, the unit size is ignored and is normally not written.)
+
+@item @var{addr}, starting display address
+@var{addr} is the address where you want _GDBN__ to begin displaying
+memory. The expression need not have a pointer value (though it may);
+it is always interpreted as an integer address of a byte of memory.
+@xref{Expressions, ,Expressions}, for more information on expressions. The default for
+@var{addr} is usually just after the last address examined---but several
+other commands also set the default address: @code{info breakpoints} (to
+the address of the last breakpoint listed), @code{info line} (to the
+starting address of a line), and @code{print} (if you use it to display
+a value from memory).
@end table
-If either the manner of printing or the size of unit fails to be specified,
-the default is to use the same one that was used last. If you don't want
-to use any letters after the slash, you can omit the slash as well.
-
-You can also omit the address to examine. Then the address used is just
-after the last unit examined. This is why string and instruction
-formats actually compute a unit-size based on the data: so that the next
-string or instruction examined will start in the right place.
-
-When the @samp{print} command shows a value that resides in memory,
-@samp{print} also sets the default address for the @samp{x} command.
-@samp{info line} also sets the default for @samp{x}, to the address of
-the start of the machine code for the specified line and @samp{info
-breakpoints} sets it to the address of the last breakpoint listed.
-
-When you use @key{RET} to repeat an @samp{x} command, the address
-specified previously (if any) is ignored, so that the repeated command
-examines the successive locations in memory rather than the same ones.
-
-You can examine several consecutive units of memory with one command by
-writing a repeat-count after the slash (before the format letters, if any).
-The repeat count must be a decimal integer. It has the same effect as
-repeating the @samp{x} command that many times except that the output may
-be more compact with several units per line. For example,
-
-@example
-x/10i $pc
-@end example
-
-@noindent
-prints ten instructions starting with the one to be executed next in the
-selected frame. After doing this, you could print another seven following
-instructions with
-
-@example
-x/7
-@end example
-
-@noindent
-in which the format and address are allowed to default.
-
-@kindex $_
-@kindex $__
-The addresses and contents printed by the @samp{x} command are not put in
-the value history because there is often too much of them and they would
-get in the way. Instead, _GDBN__ makes these values available for subsequent
-use in expressions as values of the convenience variables @code{$_} and
-@code{$__}.
-
-After an @samp{x} command, the last address examined is available for use
-in expressions in the convenience variable @code{$_}. The contents of that
-address, as examined, are available in the convenience variable @code{$__}.
-
-If the @samp{x} command has a repeat count, the address and contents saved
+For example, @samp{x/3uh 0x54320} is a request to display three halfwords
+(@code{h}) of memory, formatted as unsigned decimal integers (@samp{u}),
+starting at address @code{0x54320}. @samp{x/4xw $sp} prints the four
+words (@samp{w}) of memory above the stack pointer (here, @samp{$sp};
+@pxref{Registers}) in hexadecimal (@samp{x}).
+
+Since the letters indicating unit sizes are all distinct from the
+letters specifying output formats, you do not have to remember whether
+unit size or format comes first; either order will work. The output
+specifications @samp{4xw} and @samp{4wx} mean exactly the same thing.
+(However, the count @var{n} must come first; @samp{wx4} will not work.)
+
+Even though the unit size @var{u} is ignored for the formats @samp{s}
+and @samp{i}, you might still want to use a count @var{n}; for example,
+@samp{3i} specifies that you want to see three machine instructions,
+including any operands. The command @code{disassemble} gives an
+alternative way of inspecting machine instructions; @pxref{Machine
+Code}.
+
+All the defaults for the arguments to @code{x} are designed to make it
+easy to continue scanning memory with minimal specifications each time
+you use @code{x}. For example, after you have inspected three machine
+instructions with @samp{x/3i @var{addr}}, you can inspect the next seven
+with just @samp{x/7}. If you use @key{RET} to repeat the @code{x} command,
+the repeat count @var{n} is used again; the other arguments default as
+for successive uses of @code{x}.
+
+@cindex @code{$_}, @code{$__}, and value history
+The addresses and contents printed by the @code{x} command are not saved
+in the value history because there is often too much of them and they
+would get in the way. Instead, _GDBN__ makes these values available for
+subsequent use in expressions as values of the convenience variables
+@code{$_} and @code{$__}. After an @code{x} command, the last address
+examined is available for use in expressions in the convenience variable
+@code{$_}. The contents of that address, as examined, are available in
+the convenience variable @code{$__}.
+
+If the @code{x} command has a repeat count, the address and contents saved
are from the last memory unit printed; this is not the same as the last
address printed if several units were printed on the last line of output.
-@node Auto Display, Value History, Output formats, Data
+@node Auto Display, Print Settings, Memory, Data
@section Automatic Display
@cindex automatic display
@cindex display of expressions
If you find that you want to print the value of an expression frequently
(to see how it changes), you might want to add it to the @dfn{automatic
-display list} so that _GDBN__ will print its value each time the program stops.
+display list} so that _GDBN__ will print its value each time your program stops.
Each expression added to the list is given a number to identify it;
to remove an expression from the list, you specify that number.
The automatic display looks like this:
@end example
@noindent
-showing item numbers, expressions and their current values.
-
-If the expression refers to local variables, then it does not make sense
-outside the lexical context for which it was set up. Such an expression
-is disabled when execution enters a context where one of its variables
-is not defined. For example, if you give the command
-@samp{display name} while inside a function with an argument
-@code{name}, then this argument will be displayed while the program
-continues to stop inside that function. When it stops elsewhere---where
-there is no variable @samp{name}---display is disabled. The next time
-your program stops where @samp{name} is meaningful, you can enable the
-display expression once again.
+showing item numbers, expressions and their current values. As with
+displays you request manually using @code{x} or @code{print}, you can
+specify the output format you prefer; in fact, @code{display} decides
+whether to use @code{print} or @code{x} depending on how elaborate your
+format specification is---it uses @code{x} if you specify a unit size,
+or one of the two formats (@samp{i} and @samp{s}) that are only
+supported by @code{x}; otherwise it uses @code{print}.
@table @code
@item display @var{exp}
@kindex display
Add the expression @var{exp} to the list of expressions to display
-each time the program stops. @xref{Expressions}.
+each time your program stops. @xref{Expressions, ,Expressions}.
+
+@code{display} will not repeat if you press @key{RET} again after using it.
@item display/@var{fmt} @var{exp}
For @var{fmt} specifying only a display format and not a size or
count, add the expression @var{exp} to the auto-display list but
arranges to display it each time in the specified format @var{fmt}.
+@xref{Output formats}.
@item display/@var{fmt} @var{addr}
For @var{fmt} @samp{i} or @samp{s}, or including a unit-size or a
number of units, add the expression @var{addr} as a memory address to
-be examined each time the program stops. Examining means in effect
-doing @samp{x/@var{fmt} @var{addr}}. @xref{Memory}.
+be examined each time your program stops. Examining means in effect
+doing @samp{x/@var{fmt} @var{addr}}. @xref{Memory, ,Examining Memory}.
+@end table
+
+For example, @samp{display/i $pc} can be helpful, to see the machine
+instruction about to be executed each time execution stops (@samp{$pc}
+is a common name for the program counter; @pxref{Registers}).
+@table @code
@item undisplay @var{dnums}@dots{}
@itemx delete display @var{dnums}@dots{}
@kindex delete display
@kindex undisplay
Remove item numbers @var{dnums} from the list of expressions to display.
+@code{undisplay} will not repeat if you press @key{RET} after using it.
+(Otherwise you would just get the error @samp{No display number @dots{}}.)
+
@item disable display @var{dnums}@dots{}
@kindex disable display
Disable the display of item numbers @var{dnums}. A disabled display
@item display
Display the current values of the expressions on the list, just as is
-done when the program stops.
+done when your program stops.
@item info display
@kindex info display
because they refer to automatic variables not currently available.
@end table
-@node Value History, Convenience Vars, Auto Display, Data
-@section Value History
+If a display expression refers to local variables, then it does not make
+sense outside the lexical context for which it was set up. Such an
+expression is disabled when execution enters a context where one of its
+variables is not defined. For example, if you give the command
+@code{display last_char} while inside a function with an argument
+@code{last_char}, then this argument will be displayed while your program
+continues to stop inside that function. When it stops elsewhere---where
+there is no variable @code{last_char}---display is disabled. The next time
+your program stops where @code{last_char} is meaningful, you can enable the
+display expression once again.
-@cindex value history
-Values printed by the @samp{print} command are saved in _GDBN__'s @dfn{value
-history} so that you can refer to them in other expressions. Values are
-kept until the symbol table is re-read or discarded (for example with
-the @samp{file} or @samp{symbol-file} commands). When the symbol table
-changes, the value history is discarded, since the values may contain
-pointers back to the types defined in the symbol table.
+@node Print Settings, Value History, Auto Display, Data
+@section Print Settings
-@cindex @code{$}
-@cindex @code{$$}
-@cindex history number
-The values printed are given @dfn{history numbers} for you to refer to them
-by. These are successive integers starting with 1. @samp{print} shows you
-the history number assigned to a value by printing @samp{$@var{num} = }
-before the value; here @var{num} is the history number.
+@cindex format options
+@cindex print settings
+_GDBN__ provides the following ways to control how arrays, structures,
+and symbols are printed.
-To refer to any previous value, use @samp{$} followed by the value's
-history number. The output printed by @samp{print} is designed to
-remind you of this. Just @code{$} refers to the most recent value in
-the history, and @code{$$} refers to the value before that.
-@code{$$@var{n}} refers to the @var{n}th value from the end; @code{$$2}
-is the value just prior to @code{$$}, @code{$$1} is equivalent to
-@code{$$}, and @code{$$0} is equivalent to @code{$}.
+@noindent
+These settings are useful for debugging programs in any language:
-For example, suppose you have just printed a pointer to a structure and
-want to see the contents of the structure. It suffices to type
+@table @code
+@item set print address
+@item set print address on
+@kindex set print address
+_GDBN__ will print memory addresses showing the location of stack
+traces, structure values, pointer values, breakpoints, and so forth,
+even when it also displays the contents of those addresses. The default
+is on. For example, this is what a stack frame display looks like, with
+@code{set print address on}:
-@example
-p *$
-@end example
+@smallexample
+@group
+(_GDBP__) f
+#0 set_quotes (lq=0x34c78 "<<", rq=0x34c88 ">>")
+ at input.c:530
+530 if (lquote != def_lquote)
+@end group
+@end smallexample
-If you have a chain of structures where the component @samp{next} points
-to the next one, you can print the contents of the next one with this:
+@item set print address off
+Do not print addresses when displaying their contents. For example,
+this is the same stack frame displayed with @code{set print address off}:
@example
-p *$.next
+@group
+(_GDBP__) set print addr off
+(_GDBP__) f
+#0 set_quotes (lq="<<", rq=">>") at input.c:530
+530 if (lquote != def_lquote)
+@end group
@end example
-@noindent
-It might be useful to repeat this command many times by typing @key{RET}.
+@item show print address
+@kindex show print address
+Show whether or not addresses are to be printed.
-Note that the history records values, not expressions. If the value of
-@code{x} is 4 and you type this command:
+@item set print array
+@itemx set print array on
+@kindex set print array
+_GDBN__ will pretty print arrays. This format is more convenient to read,
+but uses more space. The default is off.
-@example
-print x
-set x=5
-@end example
+@item set print array off.
+Return to compressed format for arrays.
-@noindent
-then the value recorded in the value history by the @samp{print} command
-remains 4 even though the value of @code{x} has changed.
+@item show print array
+@kindex show print array
+Show whether compressed or pretty format is selected for displaying
+arrays.
-@table @code
-@kindex info values
-@item info values
-@itemx info history
-@kindex info history
-These two commands are synonymous. Either form will print the last ten
-values in the value history, with their item numbers. This is like
-@samp{p@ $$9} repeated ten times, except that @samp{info values} does
-not change the history.
+@item set print elements @var{number-of-elements}
+@kindex set print elements
+If _GDBN__ is printing a large array, it will stop printing after it has
+printed the number of elements set by the @code{set print elements} command.
+This limit also applies to the display of strings.
+
+@item show print elements
+@kindex show print elements
+Display the number of elements of a large array that _GDBN__ will print
+before losing patience.
+
+@item set print pretty on
+@kindex set print pretty
+Cause _GDBN__ to print structures in an indented format with one member per
+line, like this:
+
+@example
+@group
+$1 = @{
+ next = 0x0,
+ flags = @{
+ sweet = 1,
+ sour = 1
+ @},
+ meat = 0x54 "Pork"
+@}
+@end group
+@end example
+
+@item set print pretty off
+Cause _GDBN__ to print structures in a compact format, like this:
+
+@smallexample
+@group
+$1 = @{next = 0x0, flags = @{sweet = 1, sour = 1@}, \
+meat = 0x54 "Pork"@}
+@end group
+@end smallexample
+
+@noindent
+This is the default format.
+
+@item show print pretty
+@kindex show print pretty
+Show which format _GDBN__ will use to print structures.
+
+@item set print sevenbit-strings on
+@kindex set print sevenbit-strings
+Print using only seven-bit characters; if this option is set,
+_GDBN__ will display any eight-bit characters (in strings or character
+values) using the notation @code{\}@var{nnn}. For example, @kbd{M-a} is
+displayed as @code{\341}.
+
+@item set print sevenbit-strings off
+Print using either seven-bit or eight-bit characters, as required. This
+is the default.
+
+@item show print sevenbit-strings
+@kindex show print sevenbit-strings
+Show whether or not _GDBN__ will print only seven-bit characters.
+
+@item set print union on
+@kindex set print union
+Tell _GDBN__ to print unions which are contained in structures. This is the
+default setting.
+
+@item set print union off
+Tell _GDBN__ not to print unions which are contained in structures.
+
+@item show print union
+@kindex show print union
+Ask _GDBN__ whether or not it will print unions which are contained in
+structures.
+
+For example, given the declarations
+
+@smallexample
+typedef enum @{Tree, Bug@} Species;
+typedef enum @{Big_tree, Acorn, Seedling@} Tree_forms;
+typedef enum @{Caterpillar, Cocoon, Butterfly@}
+ Bug_forms;
+
+struct thing @{
+ Species it;
+ union @{
+ Tree_forms tree;
+ Bug_forms bug;
+ @} form;
+@};
+
+struct thing foo = @{Tree, @{Acorn@}@};
+@end smallexample
+
+@noindent
+with @code{set print union on} in effect @samp{p foo} would print
+
+@smallexample
+$1 = @{it = Tree, form = @{tree = Acorn, bug = Cocoon@}@}
+@end smallexample
+
+@noindent
+and with @code{set print union off} in effect it would print
+
+@smallexample
+$1 = @{it = Tree, form = @{...@}@}
+@end smallexample
+@end table
+
+@noindent
+These settings are of interest when debugging C++ programs:
+
+@table @code
+@item set print demangle
+@itemx set print demangle on
+@kindex set print demangle
+Print C++ names in their source form rather than in the mangled form
+in which they are passed to the assembler and linker for type-safe linkage.
+The default is on.
+
+@item show print demangle
+@kindex show print demangle
+Show whether C++ names will be printed in mangled or demangled form.
+
+@item set print asm-demangle
+@itemx set print asm-demangle on
+@kindex set print asm-demangle
+Print C++ names in their source form rather than their mangled form, even
+in assembler code printouts such as instruction disassemblies.
+The default is off.
+
+@item show print asm-demangle
+@kindex show print asm-demangle
+Show whether C++ names in assembly listings will be printed in mangled
+or demangled form.
+
+@item set print object
+@itemx set print object on
+@kindex set print object
+When displaying a pointer to an object, identify the @emph{actual}
+(derived) type of the object rather than the @emph{declared} type, using
+the virtual function table.
+
+@item set print object off
+Display only the declared type of objects, without reference to the
+virtual function table. This is the default setting.
+
+@item show print object
+@kindex show print object
+Show whether actual, or declared, object types will be displayed.
+
+@item set print vtbl
+@itemx set print vtbl on
+@kindex set print vtbl
+Pretty print C++ virtual function tables. The default is off.
+
+@item set print vtbl off
+Do not pretty print C++ virtual function tables.
+
+@item show print vtbl
+@kindex show print vtbl
+Show whether C++ virtual function tables are pretty printed, or not.
+@end table
+
+@node Value History, Convenience Vars, Print Settings, Data
+@section Value History
+
+@cindex value history
+Values printed by the @code{print} command are saved in _GDBN__'s @dfn{value
+history} so that you can refer to them in other expressions. Values are
+kept until the symbol table is re-read or discarded (for example with
+the @code{file} or @code{symbol-file} commands). When the symbol table
+changes, the value history is discarded, since the values may contain
+pointers back to the types defined in the symbol table.
+
+@cindex @code{$}
+@cindex @code{$$}
+@cindex history number
+The values printed are given @dfn{history numbers} for you to refer to them
+by. These are successive integers starting with one. @code{print} shows you
+the history number assigned to a value by printing @samp{$@var{num} = }
+before the value; here @var{num} is the history number.
+
+To refer to any previous value, use @samp{$} followed by the value's
+history number. The way @code{print} labels its output is designed to
+remind you of this. Just @code{$} refers to the most recent value in
+the history, and @code{$$} refers to the value before that.
+@code{$$@var{n}} refers to the @var{n}th value from the end; @code{$$2}
+is the value just prior to @code{$$}, @code{$$1} is equivalent to
+@code{$$}, and @code{$$0} is equivalent to @code{$}.
+
+For example, suppose you have just printed a pointer to a structure and
+want to see the contents of the structure. It suffices to type
+
+@example
+p *$
+@end example
+
+If you have a chain of structures where the component @code{next} points
+to the next one, you can print the contents of the next one with this:
-@item info values @var{n}
+@example
+p *$.next
+@end example
+
+@noindent
+You can print successive links in the chain by repeating this
+command---which you can do by just typing @key{RET}.
+
+Note that the history records values, not expressions. If the value of
+@code{x} is 4 and you type these commands:
+
+@example
+print x
+set x=5
+@end example
+
+@noindent
+then the value recorded in the value history by the @code{print} command
+remains 4 even though the value of @code{x} has changed.
+
+@table @code
+@kindex show values
+@item show values
+Print the last ten values in the value history, with their item numbers.
+This is like @samp{p@ $$9} repeated ten times, except that @code{show
+values} does not change the history.
+
+@item show values @var{n}
Print ten history values centered on history item number @var{n}.
-@item info values +
-Print ten history values just after the values last printed.
+@item show values +
+Print ten history values just after the values last printed. If no more
+values are available, produces no display.
@end table
+Pressing @key{RET} to repeat @code{show values @var{n}} has exactly the
+same effect as @samp{show values +}.
+
@node Convenience Vars, Registers, Value History, Data
@section Convenience Variables
@cindex convenience variables
-_GDBN__ provides @dfn{convenience variables} that you can use within _GDBN__ to
-hold on to a value and refer to it later. These variables exist entirely
-within _GDBN__; they are not part of your program, and setting a convenience
-variable has no effect on further execution of your program. That's why
-you can use them freely.
-
-Convenience variables have names starting with @samp{$}. Any name starting
-with @samp{$} can be used for a convenience variable, unless it is one of
-the predefined set of register names (@pxref{Registers}).
+_GDBN__ provides @dfn{convenience variables} that you can use within
+_GDBN__ to hold on to a value and refer to it later. These variables
+exist entirely within _GDBN__; they are not part of your program, and
+setting a convenience variable has no direct effect on further execution
+of your program. That is why you can use them freely.
+
+Convenience variables are prefixed with @samp{$}. Any name preceded by
+@samp{$} can be used for a convenience variable, unless it is one of
+the predefined machine-specific register names (@pxref{Registers}).
+(Value history references, in contrast, are @emph{numbers} preceded
+by @samp{$}. @xref{Value History, ,Value History}.)
You can save a value in a convenience variable with an assignment
expression, just as you would set a variable in your program. Example:
Convenience variables have no fixed types. You can assign a convenience
variable any type of value, including structures and arrays, even if
that variable already has a value of a different type. The convenience
-variable as an expression has whatever type its current value has.
+variable, when used as an expression, has the type of its current value.
@table @code
-@item info convenience
-@kindex info convenience
+@item show convenience
+@kindex show convenience
Print a list of convenience variables used so far, and their values.
-Abbreviated @samp{i con}.
+Abbreviated @code{show con}.
@end table
One of the ways to use a convenience variable is as a counter to be
-incremented or a pointer to be advanced. For example:
+incremented or a pointer to be advanced. For example, to print
+a field from successive elements of an array of structures:
-@example
+_0__@example
set $i = 0
print bar[$i++]->contents
-@i{@dots{}repeat that command by typing @key{RET}.}
-@end example
+@i{@dots{} repeat that command by typing @key{RET}.}
+_1__@end example
Some convenience variables are created automatically by _GDBN__ and given
values likely to be useful.
@table @code
@item $_
-The variable @code{$_} is automatically set by the @samp{x} command to
-the last address examined (@pxref{Memory}). Other commands which
-provide a default address for @samp{x} to examine also set @code{$_}
-to that address; these commands include @samp{info line} and @samp{info
-breakpoint}.
+@kindex $_
+The variable @code{$_} is automatically set by the @code{x} command to
+the last address examined (@pxref{Memory, ,Examining Memory}). Other
+commands which provide a default address for @code{x} to examine also
+set @code{$_} to that address; these commands include @code{info line}
+and @code{info breakpoint}. The type of @code{$_} is @code{void *}
+except when set by the @code{x} command, in which case it is a pointer
+to the type of @code{$__}.
@item $__
-The variable @code{$__} is automatically set by the @samp{x} command
-to the value found in the last address examined.
+@kindex $__
+The variable @code{$__} is automatically set by the @code{x} command
+to the value found in the last address examined. Its type is chosen
+to match the format in which the data was printed.
@end table
-@node Registers, , Convenience Vars, Data
+@node Registers, Floating Point Hardware, Convenience Vars, Data
@section Registers
@cindex registers
-Machine register contents can be referred to in expressions as variables
+You can refer to machine register contents, in expressions, as variables
with names starting with @samp{$}. The names of registers are different
-for each machine; use @samp{info registers} to see the names used on your
-machine. The names @code{$pc} and @code{$sp} are used on most machines for
-the program counter register and the stack pointer. Often @code{$fp} is
-used for a register that contains a pointer to the current stack frame,
-and @code{$ps} is used for a register that contains the processor
-status. These standard register names may be available on your machine
-even though the @code{info registers} command displays them with a
-different name. For example, on the SPARC, @code{info registers}
-displays the processor status register as @code{$psr} but you can also
-refer to it as @code{$ps}.
-
-_GDBN__ always considers the contents of an ordinary register as an integer
-when the register is examined in this way. Some machines have special
-registers which can hold nothing but floating point; these registers are
-considered floating point. There is no way to refer to the contents of an
-ordinary register as floating point value (although you can @emph{print}
-it as a floating point value with @samp{print/f $@var{regname}}).
-
-Some registers have distinct ``raw'' and ``virtual'' data formats. This
-means that the data format in which the register contents are saved by
-the operating system is not the same one that your program normally
-sees. For example, the registers of the 68881 floating point
-coprocessor are always saved in ``extended'' (raw) format, but all C
-programs expect to work with ``double'' (virtual) format. In such
-cases, _GDBN__ normally works with the virtual format only (the format that
-makes sense for your program), but the @samp{info registers} command
-prints the data in both formats.
-
-Register values are relative to the selected stack frame
-(@pxref{Selection}). This means that you get the value that the register
-would contain if all stack frames farther in were exited and their saved
-registers restored. In order to see the real contents of all registers,
-you must select the innermost frame (with @samp{frame 0}).
-
-Some registers are never saved (typically those numbered zero or one)
-because they are used for returning function values. In some operating
-systems (those using the ``caller saves'' convention), there are other
-registers intended for free alteration by a called routine. For these
-registers, relativization makes no difference.
+for each machine; use @code{info registers} to see the names used on
+your machine.
@table @code
@item info registers
@kindex info registers
-Print the names and relativized values of all registers.
+Print the names and values of all registers except floating-point
+registers (in the selected stack frame).
+
+@item info all-registers
+@kindex info all-registers
+@cindex floating point registers
+Print the names and values of all registers, including floating-point
+registers.
@item info registers @var{regname}
Print the relativized value of register @var{regname}. @var{regname}
or without the initial @samp{$}.
@end table
-@subsection Examples
-
-You could print the program counter in hex with
+_GDBN__ has four ``standard'' register names that are available (in
+expressions) on most machines---whenever they do not conflict with an
+architecture's canonical mnemonics for registers. The register names
+@code{$pc} and @code{$sp} are used for the program counter register and
+the stack pointer. @code{$fp} is used for a register that contains a
+pointer to the current stack frame, and @code{$ps} is used for a
+register that contains the processor status. For example,
+you could print the program counter in hex with
@example
p/x $pc
@end example
@noindent
-or add four to the stack pointer with
+or add four to the stack pointer @footnote{This is a way of removing
+one word from the stack, on machines where stacks grow downward in
+memory (most machines, nowadays). This assumes that the innermost
+stack frame is selected; setting @code{$sp} is not allowed when other
+stack frames are selected. To pop entire frames off the stack,
+regardless of machine architecture, use @code{return};
+@pxref{Returning, ,Returning from a Function}.} with
@example
set $sp += 4
@end example
-@noindent
-The last is a way of removing one word from the stack, on machines where
-stacks grow downward in memory (most machines, nowadays). This assumes
-that the innermost stack frame is selected. Setting @code{$sp} is
-not allowed when other stack frames are selected. (To pop entire frames
-off the stack, regardless of machine architecture, use @samp{return};
-@pxref{Returning}.)
-
-@node Symbols, Altering, Data, Top
-@chapter Examining the Symbol Table
+Whenever possible, these four standard register names are available on
+your machine even though the machine has different canonical mnemonics,
+so long as there is no conflict. The @code{info registers} command
+shows the canonical names. For example, on the SPARC, @code{info
+registers} displays the processor status register as @code{$psr} but you
+can also refer to it as @code{$ps}.
+
+_GDBN__ always considers the contents of an ordinary register as an
+integer when the register is examined in this way. Some machines have
+special registers which can hold nothing but floating point; these
+registers are considered to have floating point values. There is no way
+to refer to the contents of an ordinary register as floating point value
+(although you can @emph{print} it as a floating point value with
+@samp{print/f $@var{regname}}).
-The commands described in this section allow you to inquire about the
-symbols (names of variables, functions and types) defined in your
-program. This information is found by _GDBN__ in the symbol table loaded by
-the @samp{symbol-file} command; it is inherent in the text of your
-program and does not change as the program executes.
+Some registers have distinct ``raw'' and ``virtual'' data formats. This
+means that the data format in which the register contents are saved by
+the operating system is not the same one that your program normally
+sees. For example, the registers of the 68881 floating point
+coprocessor are always saved in ``extended'' (raw) format, but all C
+programs expect to work with ``double'' (virtual) format. In such
+cases, _GDBN__ normally works with the virtual format only (the format that
+makes sense for your program), but the @code{info registers} command
+prints the data in both formats.
+
+Normally, register values are relative to the selected stack frame
+(@pxref{Selection, ,Selecting a Frame}). This means that you get the
+value that the register would contain if all stack frames farther in
+were exited and their saved registers restored. In order to see the
+true contents of hardware registers, you must select the innermost
+frame (with @samp{frame 0}).
+
+However, _GDBN__ must deduce where registers are saved, from the machine
+code generated by your compiler. If some registers are not saved, or if
+_GDBN__ is unable to locate the saved registers, the selected stack
+frame will make no difference.
+_if__(_AMD29K__)
@table @code
-@item info address @var{symbol}
-@kindex info address
-Describe where the data for @var{symbol} is stored. For a register
-variable, this says which register it is kept in. For a non-register
-local variable, this prints the stack-frame offset at which the variable
-is always stored.
+@item set rstack_high_address @var{address}
+@kindex set rstack_high_address
+@cindex AMD 29K register stack
+@cindex register stack, AMD29K
+On AMD 29000 family processors, registers are saved in a separate
+``register stack''. There is no way for _GDBN__ to determine the extent
+of this stack. Normally, _GDBN__ just assumes that the stack is ``large
+enough''. This may result in _GDBN__ referencing memory locations that
+don't exist. If necessary, you can get around this problem by
+specifying the ending address of the register stack with the @code{set
+rstack_high_address} command. The argument should be an address, which
+you will probably want to precede with @samp{0x} to specify in
+hexadecimal.
-Note the contrast with @samp{print &@var{symbol}}, which does not work
-at all for a register variables, and for a stack local variable prints
-the exact address of the current instantiation of the variable.
+@item show rstack_high_address
+@kindex show rstack_high_address
+Display the current limit of the register stack, on AMD 29000 family
+processors.
+@end table
+_fi__(_AMD29K__)
-@item whatis @var{exp}
-@kindex whatis
-Print the data type of expression @var{exp}. @var{exp} is not
-actually evaluated, and any side-effecting operations (such as
-assignments or function calls) inside it do not take place.
-@xref{Expressions}.
+@node Floating Point Hardware, , Registers, Data
+@section Floating Point Hardware
+@cindex floating point
-@item whatis
-Print the data type of @code{$}, the last value in the value history.
+Depending on the host machine architecture, _GDBN__ may be able to give
+you more information about the status of the floating point hardware.
-@item ptype @var{typename}
-@kindex ptype
-Print a description of data type @var{typename}. @var{typename} may be
-the name of a type, or for C code it may have the form
-@samp{struct @var{struct-tag}}, @samp{union @var{union-tag}} or
-@samp{enum @var{enum-tag}}.@refill
+@table @code
+@item info float
+@kindex info float
+If available, provides hardware-dependent information about the floating
+point unit. The exact contents and layout vary depending on the
+floating point chip.
+@end table
+@c FIXME: this is a cop-out. Try to get examples, explanations. Only
+@c FIXME...supported currently on arm's and 386's. Mark properly with
+@c FIXME... m4 macros to isolate general statements from hardware-dep,
+@c FIXME... at that point.
+
+@node Languages, Symbols, Data, Top
+@chapter Using _GDBN__ with Different Languages
+@cindex languages
+
+Although programming languages generally have common aspects, they are
+rarely expressed in the same manner. For instance, in ANSI C,
+dereferencing a pointer @code{p} is accomplished by @code{*p}, but in
+Modula-2, it is accomplished by @code{p^}. Values can also be
+represented (and displayed) differently. Hex numbers in C are written
+like @samp{0x1ae}, while in Modula-2 they appear as @samp{1AEH}.
+
+@cindex working language
+Language-specific information is built into _GDBN__ for some languages,
+allowing you to express operations like the above in your program's
+native language, and allowing _GDBN__ to output values in a manner
+consistent with the syntax of your program's native language. The
+language you use to build expressions, called the @dfn{working
+language}, can be selected manually, or _GDBN__ can set it
+automatically.
-@item ptype @var{exp}
-Print a description of the type of expression @var{exp}. This is like
-@samp{whatis} except it prints a detailed description, instead of just
-the name of the type. For example, if the type of a variable is
-@samp{struct complex @{double real; double imag;@}}, @samp{whatis} will
-print @samp{struct complex} and @samp{ptype} will print @samp{struct
-complex @{double real; double imag;@}}
+@menu
+* Setting:: Switching between source languages
+* Show:: Displaying the language
+* Checks:: Type and Range checks
+* Support:: Supported languages
+@end menu
-@item info sources
-@kindex info sources
-Print the names of all source files in the program for which there
-is debugging information.
+@node Setting, Show, Languages, Languages
+@section Switching between source languages
-@item info functions
-@kindex info functions
-Print the names and data types of all defined functions.
+There are two ways to control the working language---either have _GDBN__
+set it automatically, or select it manually yourself. You can use the
+@code{set language} command for either purpose. On startup, _GDBN__
+defaults to setting the language automatically.
-@item info functions @var{regexp}
-Print the names and data types of all defined functions
-whose names contain a match for regular expression @var{regexp}.
-Thus, @samp{info fun step} finds all functions whose names
-include @samp{step}; @samp{info fun ^step} finds those whose names
-start with @samp{step}.
+@menu
+* Manually:: Setting the working language manually
+* Automatically:: Having _GDBN__ infer the source language
+@end menu
-@item info variables
-@kindex info variables
-Print the names and data types of all variables that are declared
-outside of functions (i.e., except for local variables).
+@node Manually, Automatically, Setting, Setting
+@subsection Setting the working language
-@item info variables @var{regexp}
-Print the names and data types of all variables (except for local
-variables) whose names contain a match for regular expression
-@var{regexp}.
+@kindex set language
+To set the language, issue the command @samp{set language @var{lang}},
+where @var{lang} is the name of a language: @code{c} or @code{modula-2}.
+For a list of the supported languages, type @samp{set language}.
+Setting the language manually prevents _GDBN__ from updating the working
+language automatically. This can lead to confusion if you try
+to debug a program when the working language is not the same as the
+source language, when an expression is acceptable to both
+languages---but means different things. For instance, if the current
+source file were written in C, and _GDBN__ was parsing Modula-2, a
+command such as:
-@ignore
-This was never implemented.
-@item info methods
-@itemx info methods @var{regexp}
-@kindex info methods
-The @samp{info-methods} command permits the user to examine all defined
-methods within C++ program, or (with the @var{regexp} argument) a
-specific set of methods found in the various C++ classes. Many
-C++ classes provide a large number of methods. Thus, the output
-from the @samp{ptype} command can be overwhelming and hard to use. The
-@samp{info-methods} command filters the methods, printing only those
-which match the regular-expression @var{regexp}.
-@end ignore
+@example
+print a = b + c
+@end example
-@item printsyms @var{filename}
-@kindex printsyms
-Write a complete dump of the debugger's symbol data into the
-file @var{filename}.
+@noindent
+might not have the effect you intended. In C, this means to add
+@code{b} and @code{c} and place the result in @code{a}. The result
+printed would be the value of @code{a}. In Modula-2, this means to compare
+@code{a} to the result of @code{b+c}, yielding a @code{BOOLEAN} value.
+
+If you allow _GDBN__ to set the language automatically, then
+you can count on expressions evaluating the same way in your debugging
+session and in your program.
+
+@node Automatically, , Manually, Setting
+@subsection Having _GDBN__ infer the source language
+
+To have _GDBN__ set the working language automatically, use @samp{set
+language local} or @samp{set language auto}. _GDBN__ then infers the
+language that a program was written in by looking at the name of its
+source files, and examining their extensions:
+
+@table @file
+@item *.mod
+Modula-2 source file
+
+@item *.c
+@itemx *.cc
+C or C++ source file.
@end table
-@node Altering, Sequences, Symbols, Top
-@chapter Altering Execution
+This information is recorded for each function or procedure in a source
+file. When your program stops in a frame (usually by encountering a
+breakpoint), _GDBN__ sets the working language to the language recorded
+for the function in that frame. If the language for a frame is unknown
+(that is, if the function or block corresponding to the frame was
+defined in a source file that does not have a recognized extension), the
+current working language is not changed, and _GDBN__ issues a warning.
-Once you think you have found an error in the program, you might want to
-find out for certain whether correcting the apparent error would lead to
-correct results in the rest of the run. You can find the answer by
-experiment, using the _GDBN__ features for altering execution of the
-program.
+This may not seem necessary for most programs, which are written
+entirely in one source language. However, program modules and libraries
+written in one source language can be used by a main program written in
+a different source language. Using @samp{set language auto} in this
+case frees you from having to set the working language manually.
-For example, you can store new values into variables or memory
-locations, give the program a signal, restart it at a different address,
-or even return prematurely from a function to its caller.
+@node Show, Checks, Setting, Languages
+@section Displaying the language
-@menu
-* Assignment:: Altering variable values or memory contents.
-* Jumping:: Altering control flow.
-* Signaling:: Making signals happen in the program.
-* Returning:: Making a function return prematurely.
-* Calling:: Calling functions from your program
-@end menu
+The following commands will help you find out which language is the
+working language, and also what language source files were written in.
-@node Assignment, Jumping, Altering, Altering
-@section Assignment to Variables
+@kindex show language
+@kindex info frame
+@kindex info source
+@table @code
+@item show language
+Display the current working language. This is the
+language you can use with commands such as @code{print} to
+build and compute expressions that may involve variables in your program.
+
+@item info frame
+Among the other information listed here (@pxref{Frame Info, ,Information
+about a Frame}) is the source language for this frame. This is the
+language that will become the working language if you ever use an
+identifier that is in this frame.
+
+@item info source
+Among the other information listed here (@pxref{Symbols, ,Examining the
+Symbol Table}) is the source language of this source file.
+@end table
+
+@node Checks, Support, Show, Languages
+@section Type and range Checking
+
+@quotation
+@emph{Warning:} In this release, the _GDBN__ commands for type and range
+checking are included, but they do not yet have any effect. This
+section documents the intended facilities.
+@end quotation
+@c FIXME remove warning when type/range code added
+
+Some languages are designed to guard you against making seemingly common
+errors through a series of compile- and run-time checks. These include
+checking the type of arguments to functions and operators, and making
+sure mathematical overflows are caught at run time. Checks such as
+these help to ensure a program's correctness once it has been compiled
+by eliminating type mismatches, and providing active checks for range
+errors when your program is running.
+
+_GDBN__ can check for conditions like the above if you wish.
+Although _GDBN__ will not check the statements in your program, it
+can check expressions entered directly into _GDBN__ for evaluation via
+the @code{print} command, for example. As with the working language,
+_GDBN__ can also decide whether or not to check automatically based on
+your program's source language. @xref{Support, ,Supported Languages},
+for the default settings of supported languages.
+
+@menu
+* Type Checking:: An overview of type checking
+* Range Checking:: An overview of range checking
+@end menu
+
+@cindex type checking
+@cindex checks, type
+@node Type Checking, Range Checking, Checks, Checks
+@subsection An overview of type checking
+
+Some languages, such as Modula-2, are strongly typed, meaning that the
+arguments to operators and functions have to be of the correct type,
+otherwise an error occurs. These checks prevent type mismatch
+errors from ever causing any run-time problems. For example,
+
+@example
+1 + 2 @result{} 3
+@exdent but
+@error{} 1 + 2.3
+@end example
+
+The second example fails because the @code{CARDINAL} 1 is not
+type-compatible with the @code{REAL} 2.3.
+
+For expressions you use in _GDBN__ commands, you can tell the _GDBN__
+type checker to skip checking; to treat any mismatches as errors and
+abandon the expression; or only issue warnings when type mismatches
+occur, but evaluate the expression anyway. When you choose the last of
+these, _GDBN__ evaluates expressions like the second example above, but
+also issues a warning.
+
+Even though you may turn type checking off, other type-based reasons may
+prevent _GDBN__ from evaluating an expression. For instance, _GDBN__ does not
+know how to add an @code{int} and a @code{struct foo}. These particular
+type errors have nothing to do with the language in use, and usually
+arise from expressions, such as the one described above, which make
+little sense to evaluate anyway.
+
+Each language defines to what degree it is strict about type. For
+instance, both Modula-2 and C require the arguments to arithmetical
+operators to be numbers. In C, enumerated types and pointers can be
+represented as numbers, so that they are valid arguments to mathematical
+operators. @xref{Support, ,Supported Languages}, for further
+details on specific languages.
+
+_GDBN__ provides some additional commands for controlling the type checker:
+
+@kindex set check
+@kindex set check type
+@kindex show check type
+@table @code
+@item set check type auto
+Set type checking on or off based on the current working language.
+@xref{Support, ,Supported Languages}, for the default settings for
+each language.
+
+@item set check type on
+@itemx set check type off
+Set type checking on or off, overriding the default setting for the
+current working language. Issue a warning if the setting does not
+match the language's default. If any type mismatches occur in
+evaluating an expression while typechecking is on, _GDBN__ prints a
+message and aborts evaluation of the expression.
+
+@item set check type warn
+Cause the type checker to issue warnings, but to always attempt to
+evaluate the expression. Evaluating the expression may still
+be impossible for other reasons. For example, _GDBN__ cannot add
+numbers and structures.
+
+@item show type
+Show the current setting of the type checker, and whether or not _GDBN__ is
+setting it automatically.
+@end table
+
+@cindex range checking
+@cindex checks, range
+@node Range Checking, , Type Checking, Checks
+@subsection An overview of Range Checking
+
+In some languages (such as Modula-2), it is an error to exceed the
+bounds of a type; this is enforced with run-time checks. Such range
+checking is meant to ensure program correctness by making sure
+computations do not overflow, or indices on an array element access do
+not exceed the bounds of the array.
+
+For expressions you use in _GDBN__ commands, you can tell _GDBN__ to
+ignore range errors; to always treat them as errors and abandon the
+expression; or to issue warnings when a range error occurs but evaluate
+the expression anyway.
+
+A range error can result from numerical overflow, from exceeding an
+array index bound, or when you type in a constant that is not a member
+of any type. Some languages, however, do not treat overflows as an
+error. In many implementations of C, mathematical overflow causes the
+result to ``wrap around'' to lower values---for example, if @var{m} is
+the largest integer value, and @var{s} is the smallest, then
+
+@example
+@var{m} + 1 @result{} @var{s}
+@end example
+
+This, too, is specific to individual languages, and in some cases
+specific to individual compilers or machines. @xref{Support, ,
+Supported Languages}, for further details on specific languages.
+
+_GDBN__ provides some additional commands for controlling the range checker:
+
+@kindex set check
+@kindex set check range
+@kindex show check range
+@table @code
+@item set check range auto
+Set range checking on or off based on the current working language.
+@xref{Support, ,Supported Languages}, for the default settings for
+each language.
+
+@item set check range on
+@itemx set check range off
+Set range checking on or off, overriding the default setting for the
+current working language. A warning is issued if the setting does not
+match the language's default. If a range error occurs, then a message
+is printed and evaluation of the expression is aborted.
+
+@item set check range warn
+Output messages when the _GDBN__ range checker detects a range error,
+but attempt to evaluate the expression anyway. Evaluating the
+expression may still be impossible for other reasons, such as accessing
+memory that the process does not own (a typical example from many UNIX
+systems).
+
+@item show range
+Show the current setting of the range checker, and whether or not it is
+being set automatically by _GDBN__.
+@end table
+
+@node Support, , Checks, Languages
+@section Supported Languages
+
+_GDBN__ 4 supports C, C++, and Modula-2. The syntax for C and C++ is so
+closely related that _GDBN__ does not distinguish the two. Some _GDBN__
+features may be used in expressions regardless of the language you
+use: the _GDBN__ @code{@@} and @code{::} operators, and the
+@samp{@{type@}addr} construct (@pxref{Expressions, ,Expressions}) can be
+used with the constructs of any of the supported languages.
+
+The following sections detail to what degree each of these
+source languages is supported by _GDBN__. These sections are
+not meant to be language tutorials or references, but serve only as a
+reference guide to what the _GDBN__ expression parser will accept, and
+what input and output formats should look like for different languages.
+There are many good books written on each of these languages; please
+look to these for a language reference or tutorial.
+
+@menu
+* C:: C and C++
+* Modula-2:: Modula-2
+@end menu
+
+@node C, Modula-2, Support, Support
+@subsection C and C++
+@cindex C and C++
+
+@cindex expressions in C or C++
+Since C and C++ are so closely related, _GDBN__ does not distinguish
+between them when interpreting the expressions recognized in _GDBN__
+commands.
+
+@cindex C++
+@kindex g++
+@cindex GNU C++
+The C++ debugging facilities are jointly implemented by the GNU C++
+compiler and _GDBN__. Therefore, to debug your C++ code effectively,
+you must compile your C++ programs with the GNU C++ compiler,
+@code{g++}.
+
+@menu
+* C Operators:: C and C++ Operators
+* C Constants:: C and C++ Constants
+* Cplusplus expressions:: C++ Expressions
+* C Defaults:: Default settings for C and C++
+* C Checks:: C and C++ Type and Range Checks
+* Debugging C:: _GDBN__ and C
+* Debugging C plus plus:: Special features for C++
+@end menu
+
+@cindex C and C++ operators
+@node C Operators, C Constants, C, C
+@subsubsection C and C++ Operators
+
+Operators must be defined on values of specific types. For instance,
+@code{+} is defined on numbers, but not on structures. Operators are
+often defined on groups of types. For the purposes of C and C++, the
+following definitions hold:
+
+@itemize @bullet
+@item
+@emph{Integral types} include @code{int} with any of its storage-class
+specifiers, @code{char}, and @code{enum}s.
+
+@item
+@emph{Floating-point types} include @code{float} and @code{double}.
+
+@item
+@emph{Pointer types} include all types defined as @code{(@var{type}
+*)}.
+
+@item
+@emph{Scalar types} include all of the above.
+@end itemize
+
+@noindent
+The following operators are supported. They are listed here
+in order of increasing precedence:
+
+@table @code
+_0__@item ,
+The comma or sequencing operator. Expressions in a comma-separated list
+are evaluated from left to right, with the result of the entire
+expression being the last expression evaluated.
+
+@item =
+Assignment. The value of an assignment expression is the value
+assigned. Defined on scalar types.
+
+@item @var{op}=
+Used in an expression of the form @w{@code{@var{a} @var{op}= @var{b}}},
+and translated to @w{@code{@var{a} = @var{a op b}}}.
+@w{@code{@var{op}=}} and @code{=} have the same precendence.
+@var{op} is any one of the operators @code{|}, @code{^}, @code{&},
+@code{<<}, @code{>>}, @code{+}, @code{-}, @code{*}, @code{/}, @code{%}.
+
+@item ?:
+The ternary operator. @code{@var{a} ? @var{b} : @var{c}} can be thought
+of as: if @var{a} then @var{b} else @var{c}. @var{a} should be of an
+integral type.
+
+@item ||
+Logical @sc{or}. Defined on integral types.
+
+@item &&
+Logical @sc{and}. Defined on integral types.
+
+@item |
+Bitwise @sc{or}. Defined on integral types.
+
+@item ^
+Bitwise exclusive-@sc{or}. Defined on integral types.
+
+@item &
+Bitwise @sc{and}. Defined on integral types.
+
+@item ==@r{, }!=
+Equality and inequality. Defined on scalar types. The value of these
+expressions is 0 for false and non-zero for true.
+
+@item <@r{, }>@r{, }<=@r{, }>=
+Less than, greater than, less than or equal, greater than or equal.
+Defined on scalar types. The value of these expressions is 0 for false
+and non-zero for true.
+
+@item <<@r{, }>>
+left shift, and right shift. Defined on integral types.
+
+@item @@
+The _GDBN__ ``artificial array'' operator (@pxref{Expressions, ,Expressions}).
+
+@item +@r{, }-
+Addition and subtraction. Defined on integral types, floating-point types and
+pointer types.
+
+@item *@r{, }/@r{, }%
+Multiplication, division, and modulus. Multiplication and division are
+defined on integral and floating-point types. Modulus is defined on
+integral types.
+
+@item ++@r{, }--
+Increment and decrement. When appearing before a variable, the
+operation is performed before the variable is used in an expression;
+when appearing after it, the variable's value is used before the
+operation takes place.
+
+@item *
+Pointer dereferencing. Defined on pointer types. Same precedence as
+@code{++}.
+
+@item &
+Address operator. Defined on variables. Same precedence as @code{++}.
+
+For debugging C++, _GDBN__ implements a use of @samp{&} beyond what's
+allowed in the C++ language itself: you can use @samp{&(&@var{ref})}
+(or, if you prefer, simply @samp{&&@var{ref}} to examine the address
+where a C++ reference variable (declared with @samp{&@var{ref}}) is
+stored.
+
+@item -
+Negative. Defined on integral and floating-point types. Same
+precedence as @code{++}.
+
+@item !
+Logical negation. Defined on integral types. Same precedence as
+@code{++}.
+
+@item ~
+Bitwise complement operator. Defined on integral types. Same precedence as
+@code{++}.
+
+@item .@r{, }->
+Structure member, and pointer-to-structure member. For convenience,
+_GDBN__ regards the two as equivalent, choosing whether to dereference a
+pointer based on the stored type information.
+Defined on @code{struct}s and @code{union}s.
+
+@item []
+Array indexing. @code{@var{a}[@var{i}]} is defined as
+@code{*(@var{a}+@var{i})}. Same precedence as @code{->}.
+
+@item ()
+Function parameter list. Same precedence as @code{->}.
+
+@item ::
+C++ scope resolution operator. Defined on
+@code{struct}, @code{union}, and @code{class} types.
+
+@item ::
+The _GDBN__ scope operator (@pxref{Expressions, ,Expressions}). Same precedence as
+@code{::}, above._1__
+@end table
+
+@cindex C and C++ constants
+@node C Constants, Cplusplus expressions, C Operators, C
+@subsubsection C and C++ Constants
+
+_GDBN__ allows you to express the constants of C and C++ in the
+following ways:
+
+@itemize @bullet
+@item
+Integer constants are a sequence of digits. Octal constants are
+specified by a leading @samp{0} (ie. zero), and hexadecimal constants by
+a leading @samp{0x} or @samp{0X}. Constants may also end with a letter
+@samp{l}, specifying that the constant should be treated as a
+@code{long} value.
+
+@item
+Floating point constants are a sequence of digits, followed by a decimal
+point, followed by a sequence of digits, and optionally followed by an
+exponent. An exponent is of the form:
+@samp{@w{e@r{[[}+@r{]|}-@r{]}@var{nnn}}}, where @var{nnn} is another
+sequence of digits. The @samp{+} is optional for positive exponents.
+
+@item
+Enumerated constants consist of enumerated identifiers, or their
+integral equivalents.
+
+@item
+Character constants are a single character surrounded by single quotes
+(@code{'}), or a number---the ordinal value of the corresponding character
+(usually its @sc{ASCII} value). Within quotes, the single character may
+be represented by a letter or by @dfn{escape sequences}, which are of
+the form @samp{\@var{nnn}}, where @var{nnn} is the octal representation
+of the character's ordinal value; or of the form @samp{\@var{x}}, where
+@samp{@var{x}} is a predefined special character---for example,
+@samp{\n} for newline.
+
+@item
+String constants are a sequence of character constants surrounded
+by double quotes (@code{"}).
+
+@item
+Pointer constants are an integral value.
+@end itemize
+
+@node Cplusplus expressions, C Defaults, C Constants, C
+@subsubsection C++ Expressions
+
+@cindex expressions in C++
+_GDBN__'s expression handling has the following extensions to
+interpret a significant subset of C++ expressions:
+
+@enumerate
+
+@cindex member functions
+@item
+Member function calls are allowed; you can use expressions like
+
+@example
+count = aml->GetOriginal(x, y)
+@end example
+
+@kindex this
+@cindex namespace in C++
+@item
+While a member function is active (in the selected stack frame), your
+expressions have the same namespace available as the member function;
+that is, _GDBN__ allows implicit references to the class instance
+pointer @code{this} following the same rules as C++.
+
+@cindex call overloaded functions
+@cindex type conversions in C++
+@item
+You can call overloaded functions; _GDBN__ will resolve the function
+call to the right definition, with one restriction---you must use
+arguments of the type required by the function that you want to call.
+_GDBN__ will not perform conversions requiring constructors or
+user-defined type operators.
+
+@cindex reference declarations
+@item
+_GDBN__ understands variables declared as C++ references; you can use them in
+expressions just as you do in C++ source---they are automatically
+dereferenced.
+
+In the parameter list shown when _GDBN__ displays a frame, the values of
+reference variables are not displayed (unlike other variables); this
+avoids clutter, since references are often used for large structures.
+The @emph{address} of a reference variable is always shown, unless
+you have specified @samp{set print address off}.
+
+@item
+_GDBN__ supports the C++ name resolution operator @code{::}---your
+expressions can use it just as expressions in your program do. Since
+one scope may be defined in another, you can use @code{::} repeatedly if
+necessary, for example in an expression like
+@samp{@var{scope1}::@var{scope2}::@var{name}}. _GDBN__ also allows
+resolving name scope by reference to source files, in both C and C++
+debugging (@pxref{Variables, ,Program Variables}).
+@end enumerate
+
+@node C Defaults, C Checks, Cplusplus expressions, C
+@subsubsection C and C++ Defaults
+@cindex C and C++ defaults
+
+If you allow _GDBN__ to set type and range checking automatically, they
+both default to @code{off} whenever the working language changes to
+C/C++. This happens regardless of whether you, or _GDBN__,
+selected the working language.
+
+If you allow _GDBN__ to set the language automatically, it sets the
+working language to C/C++ on entering code compiled from a source file
+whose name ends with @file{.c} or @file{.cc}.
+@xref{Automatically, ,Having _GDBN__ infer the source language}, for
+further details.
+
+@node C Checks, Debugging C, C Defaults, C
+@subsubsection C and C++ Type and Range Checks
+@cindex C and C++ checks
+
+@quotation
+@emph{Warning:} in this release, _GDBN__ does not yet perform type or
+range checking.
+@end quotation
+@c FIXME remove warning when type/range checks added
+
+By default, when _GDBN__ parses C or C++ expressions, type checking
+is not used. However, if you turn type checking on, _GDBN__ will
+consider two variables type equivalent if:
+
+@itemize @bullet
+@item
+The two variables are structured and have the same structure, union, or
+enumerated tag.
+
+@item
+Two two variables have the same type name, or types that have been
+declared equivalent through @code{typedef}.
+
+@ignore
+@c leaving this out because neither J Gilmore nor R Pesch understand it.
+@c FIXME--beers?
+@item
+The two @code{struct}, @code{union}, or @code{enum} variables are
+declared in the same declaration. (Note: this may not be true for all C
+compilers.)
+@end ignore
+@end itemize
+
+Range checking, if turned on, is done on mathematical operations. Array
+indices are not checked, since they are often used to index a pointer
+that is not itself an array.
+
+@node Debugging C, Debugging C plus plus, C Checks, C
+@subsubsection _GDBN__ and C
+
+The @code{set print union} and @code{show print union} commands apply to
+the @code{union} type. When set to @samp{on}, any @code{union} that is
+inside a @code{struct} or @code{class} will also be printed.
+Otherwise, it will appear as @samp{@{...@}}.
+
+The @code{@@} operator aids in the debugging of dynamic arrays, formed
+with pointers and a memory allocation function. (@pxref{Expressions, ,Expressions})
+
+@node Debugging C plus plus, , Debugging C, C
+@subsubsection _GDBN__ Features for C++
+
+@cindex commands for C++
+Some _GDBN__ commands are particularly useful with C++, and some are
+designed specifically for use with C++. Here is a summary:
+
+@table @code
+@cindex break in overloaded functions
+@item @r{breakpoint menus}
+When you want a breakpoint in a function whose name is overloaded,
+_GDBN__'s breakpoint menus help you specify which function definition
+you want. @xref{Breakpoint Menus}.
+
+@cindex overloading in C++
+@item rbreak @var{regex}
+Setting breakpoints using regular expressions is helpful for setting
+breakpoints on overloaded functions that are not members of any special
+classes.
+@xref{Set Breaks, ,Setting Breakpoints}.
+
+@cindex C++ exception handling
+@item catch @var{exceptions}
+@itemx info catch
+Debug C++ exception handling using these commands. @xref{Exception
+Handling, ,Breakpoints and Exceptions}.
+
+@cindex inheritance
+@item ptype @var{typename}
+Print inheritance relationships as well as other information for type
+@var{typename}.
+@xref{Symbols, ,Examining the Symbol Table}.
+
+@cindex C++ symbol display
+@item set print demangle
+@itemx show print demangle
+@itemx set print asm-demangle
+@itemx show print asm-demangle
+Control whether C++ symbols display in their source form, both when
+displaying code as C++ source and when displaying disassemblies.
+@xref{Print Settings, ,Print Settings}.
+
+@item set print object
+@itemx show print object
+Choose whether to print derived (actual) or declared types of objects.
+@xref{Print Settings, ,Print Settings}.
+
+@item set print vtbl
+@itemx show print vtbl
+Control the format for printing virtual function tables.
+@xref{Print Settings, ,Print Settings}.
+
+@item @r{Overloaded symbol names}
+You can specify a particular definition of an overloaded symbol, using
+the same notation that's used to declare such symbols in C++: type
+@code{@var{symbol}(@var{types})} rather than just @var{symbol}. You can
+also use _GDBN__'s command-line word completion facilities to list the
+available choices, or to finish the type list for you.
+@xref{Completion,, Command Completion}, for details on how to do this.
+@end table
+
+@node Modula-2, , C, Support
+@subsection Modula-2
+@cindex Modula-2
+
+The extensions made to _GDBN__ to support Modula-2 support output
+from the GNU Modula-2 compiler (which is currently being developed).
+Other Modula-2 compilers are not currently supported, and attempting to
+debug executables produced by them will most likely result in an error
+as _GDBN__ reads in the executable's symbol table.
+
+@cindex expressions in Modula-2
+@menu
+* M2 Operators:: Built-in operators
+* Built-In Func/Proc:: Built-in Functions and Procedures
+* M2 Constants:: Modula-2 Constants
+* M2 Defaults:: Default settings for Modula-2
+* Deviations:: Deviations from standard Modula-2
+* M2 Checks:: Modula-2 Type and Range Checks
+* M2 Scope:: The scope operators @code{::} and @code{.}
+* GDB/M2:: _GDBN__ and Modula-2
+@end menu
+
+@node M2 Operators, Built-In Func/Proc, Modula-2, Modula-2
+@subsubsection Operators
+@cindex Modula-2 operators
+
+Operators must be defined on values of specific types. For instance,
+@code{+} is defined on numbers, but not on structures. Operators are
+often defined on groups of types. For the purposes of Modula-2, the
+following definitions hold:
+
+@itemize @bullet
+
+@item
+@emph{Integral types} consist of @code{INTEGER}, @code{CARDINAL}, and
+their subranges.
+
+@item
+@emph{Character types} consist of @code{CHAR} and its subranges.
+
+@item
+@emph{Floating-point types} consist of @code{REAL}.
+
+@item
+@emph{Pointer types} consist of anything declared as @code{POINTER TO
+@var{type}}.
+
+@item
+@emph{Scalar types} consist of all of the above.
+
+@item
+@emph{Set types} consist of @code{SET}s and @code{BITSET}s.
+
+@item
+@emph{Boolean types} consist of @code{BOOLEAN}.
+@end itemize
+
+@noindent
+The following operators are supported, and appear in order of
+increasing precedence:
+
+@table @code
+@item ,
+Function argument or array index separator.
+_0__
+@item :=
+Assignment. The value of @var{var} @code{:=} @var{value} is
+@var{value}.
+
+@item <@r{, }>
+Less than, greater than on integral, floating-point, or enumerated
+types.
+
+@item <=@r{, }>=
+Less than, greater than, less than or equal to, greater than or equal to
+on integral, floating-point and enumerated types, or set inclusion on
+set types. Same precedence as @code{<}.
+
+@item =@r{, }<>@r{, }#
+Equality and two ways of expressing inequality, valid on scalar types.
+Same precedence as @code{<}. In _GDBN__ scripts, only @code{<>} is
+available for inequality, since @code{#} conflicts with the script
+comment character.
+
+@item IN
+Set membership. Defined on set types and the types of their members.
+Same precedence as @code{<}.
+
+@item OR
+Boolean disjunction. Defined on boolean types.
+
+@item AND@r{, }&
+Boolean conjuction. Defined on boolean types.
+
+@item @@
+The _GDBN__ ``artificial array'' operator (@pxref{Expressions, ,Expressions}).
+
+@item +@r{, }-
+Addition and subtraction on integral and floating-point types, or union
+and difference on set types.
+
+@item *
+Multiplication on integral and floating-point types, or set intersection
+on set types.
+
+@item /
+Division on floating-point types, or symmetric set difference on set
+types. Same precedence as @code{*}.
+
+@item DIV@r{, }MOD
+Integer division and remainder. Defined on integral types. Same
+precedence as @code{*}.
+
+@item -
+Negative. Defined on @code{INTEGER}s and @code{REAL}s.
+
+@item ^
+Pointer dereferencing. Defined on pointer types.
+
+@item NOT
+Boolean negation. Defined on boolean types. Same precedence as
+@code{^}.
+
+@item .
+@code{RECORD} field selector. Defined on @code{RECORD}s. Same
+precedence as @code{^}.
+
+@item []
+Array indexing. Defined on @code{ARRAY}s. Same precedence as @code{^}.
+
+@item ()
+Procedure argument list. Defined on @code{PROCEDURE}s. Same precedence
+as @code{^}.
+
+@item ::@r{, }.
+_GDBN__ and Modula-2 scope operators.
+@end table
+
+@quotation
+@emph{Warning:} Sets and their operations are not yet supported, so _GDBN__
+will treat the use of the operator @code{IN}, or the use of operators
+@code{+}, @code{-}, @code{*}, @code{/}, @code{=}, , @code{<>}, @code{#},
+@code{<=}, and @code{>=} on sets as an error.
+@end quotation
+_1__
+@cindex Modula-2 built-ins
+@node Built-In Func/Proc, M2 Constants, M2 Operators, Modula-2
+@subsubsection Built-in Functions and Procedures
+
+Modula-2 also makes available several built-in procedures and functions.
+In describing these, the following metavariables are used:
+
+@table @var
+
+@item a
+represents an @code{ARRAY} variable.
+
+@item c
+represents a @code{CHAR} constant or variable.
+
+@item i
+represents a variable or constant of integral type.
+
+@item m
+represents an identifier that belongs to a set. Generally used in the
+same function with the metavariable @var{s}. The type of @var{s} should
+be @code{SET OF @var{mtype}} (where @var{mtype} is the type of @var{m}.
+
+@item n
+represents a variable or constant of integral or floating-point type.
+
+@item r
+represents a variable or constant of floating-point type.
+
+@item t
+represents a type.
+
+@item v
+represents a variable.
+
+@item x
+represents a variable or constant of one of many types. See the
+explanation of the function for details.
+@end table
+
+All Modula-2 built-in procedures also return a result, described below.
+
+@table @code
+@item ABS(@var{n})
+Returns the absolute value of @var{n}.
+
+@item CAP(@var{c})
+If @var{c} is a lower case letter, it returns its upper case
+equivalent, otherwise it returns its argument
+
+@item CHR(@var{i})
+Returns the character whose ordinal value is @var{i}.
+
+@item DEC(@var{v})
+Decrements the value in the variable @var{v}. Returns the new value.
+
+@item DEC(@var{v},@var{i})
+Decrements the value in the variable @var{v} by @var{i}. Returns the
+new value.
+
+@item EXCL(@var{m},@var{s})
+Removes the element @var{m} from the set @var{s}. Returns the new
+set.
+
+@item FLOAT(@var{i})
+Returns the floating point equivalent of the integer @var{i}.
+
+@item HIGH(@var{a})
+Returns the index of the last member of @var{a}.
+
+@item INC(@var{v})
+Increments the value in the variable @var{v}. Returns the new value.
+
+@item INC(@var{v},@var{i})
+Increments the value in the variable @var{v} by @var{i}. Returns the
+new value.
+
+@item INCL(@var{m},@var{s})
+Adds the element @var{m} to the set @var{s} if it is not already
+there. Returns the new set.
+
+@item MAX(@var{t})
+Returns the maximum value of the type @var{t}.
+
+@item MIN(@var{t})
+Returns the minimum value of the type @var{t}.
+
+@item ODD(@var{i})
+Returns boolean TRUE if @var{i} is an odd number.
+
+@item ORD(@var{x})
+Returns the ordinal value of its argument. For example, the ordinal
+value of a character is its ASCII value (on machines supporting the
+ASCII character set). @var{x} must be of an ordered type, which include
+integral, character and enumerated types.
+
+@item SIZE(@var{x})
+Returns the size of its argument. @var{x} can be a variable or a type.
+
+@item TRUNC(@var{r})
+Returns the integral part of @var{r}.
+
+@item VAL(@var{t},@var{i})
+Returns the member of the type @var{t} whose ordinal value is @var{i}.
+@end table
+
+@quotation
+@emph{Warning:} Sets and their operations are not yet supported, so
+_GDBN__ will treat the use of procedures @code{INCL} and @code{EXCL} as
+an error.
+@end quotation
+
+@cindex Modula-2 constants
+@node M2 Constants, M2 Defaults, Built-In Func/Proc, Modula-2
+@subsubsection Constants
+
+_GDBN__ allows you to express the constants of Modula-2 in the following
+ways:
+
+@itemize @bullet
+
+@item
+Integer constants are simply a sequence of digits. When used in an
+expression, a constant is interpreted to be type-compatible with the
+rest of the expression. Hexadecimal integers are specified by a
+trailing @samp{H}, and octal integers by a trailing @samp{B}.
+
+@item
+Floating point constants appear as a sequence of digits, followed by a
+decimal point and another sequence of digits. An optional exponent can
+then be specified, in the form @samp{E@r{[}+@r{|}-@r{]}@var{nnn}}, where
+@samp{@r{[}+@r{|}-@r{]}@var{nnn}} is the desired exponent. All of the
+digits of the floating point constant must be valid decimal (base 10)
+digits.
+
+@item
+Character constants consist of a single character enclosed by a pair of
+like quotes, either single (@code{'}) or double (@code{"}). They may
+also be expressed by their ordinal value (their ASCII value, usually)
+followed by a @samp{C}.
+
+@item
+String constants consist of a sequence of characters enclosed by a
+pair of like quotes, either single (@code{'}) or double (@code{"}).
+Escape sequences in the style of C are also allowed. @xref{C
+Constants, ,C and C++ Constants}, for a brief explanation of escape
+sequences.
+
+@item
+Enumerated constants consist of an enumerated identifier.
+
+@item
+Boolean constants consist of the identifiers @code{TRUE} and
+@code{FALSE}.
+
+@item
+Pointer constants consist of integral values only.
+
+@item
+Set constants are not yet supported.
+@end itemize
+
+@node M2 Defaults, Deviations, M2 Constants, Modula-2
+@subsubsection Modula-2 Defaults
+@cindex Modula-2 defaults
+
+If type and range checking are set automatically by _GDBN__, they
+both default to @code{on} whenever the working language changes to
+Modula-2. This happens regardless of whether you, or _GDBN__,
+selected the working language.
+
+If you allow _GDBN__ to set the language automatically, then entering
+code compiled from a file whose name ends with @file{.mod} will set the
+working language to Modula-2. @xref{Automatically, ,Having _GDBN__ set
+the language automatically}, for further details.
+
+@node Deviations, M2 Checks, M2 Defaults, Modula-2
+@subsubsection Deviations from Standard Modula-2
+@cindex Modula-2, deviations from
+
+A few changes have been made to make Modula-2 programs easier to debug.
+This is done primarily via loosening its type strictness:
+
+@itemize @bullet
+@item
+Unlike in standard Modula-2, pointer constants can be formed by
+integers. This allows you to modify pointer variables during
+debugging. (In standard Modula-2, the actual address contained in a
+pointer variable is hidden from you; it can only be modified
+through direct assignment to another pointer variable or expression that
+returned a pointer.)
+
+@item
+C escape sequences can be used in strings and characters to represent
+non-printable characters. _GDBN__ will print out strings with these
+escape sequences embedded. Single non-printable characters are
+printed using the @samp{CHR(@var{nnn})} format.
+
+@item
+The assignment operator (@code{:=}) returns the value of its right-hand
+argument.
+
+@item
+All built-in procedures both modify @emph{and} return their argument.
+@end itemize
+
+@node M2 Checks, M2 Scope, Deviations, Modula-2
+@subsubsection Modula-2 Type and Range Checks
+@cindex Modula-2 checks
+
+@quotation
+@emph{Warning:} in this release, _GDBN__ does not yet perform type or
+range checking.
+@end quotation
+@c FIXME remove warning when type/range checks added
+
+_GDBN__ considers two Modula-2 variables type equivalent if:
+
+@itemize @bullet
+@item
+They are of types that have been declared equivalent via a @code{TYPE
+@var{t1} = @var{t2}} statement
+
+@item
+They have been declared on the same line. (Note: This is true of the
+GNU Modula-2 compiler, but it may not be true of other compilers.)
+@end itemize
+
+As long as type checking is enabled, any attempt to combine variables
+whose types are not equivalent is an error.
+
+Range checking is done on all mathematical operations, assignment, array
+index bounds, and all built-in functions and procedures.
+
+@node M2 Scope, GDB/M2, M2 Checks, Modula-2
+@subsubsection The scope operators @code{::} and @code{.}
+@cindex scope
+@kindex .
+@cindex colon, doubled as scope operator
+@ifinfo
+@kindex colon-colon
+@c Info cannot handoe :: but TeX can.
+@end ifinfo
+@iftex
+@kindex ::
+@end iftex
+
+There are a few subtle differences between the Modula-2 scope operator
+(@code{.}) and the _GDBN__ scope operator (@code{::}). The two have
+similar syntax:
+
+@example
+
+@var{module} . @var{id}
+@var{scope} :: @var{id}
+@end example
+
+@noindent
+where @var{scope} is the name of a module or a procedure,
+@var{module} the name of a module, and @var{id} is any declared
+identifier within your program, except another module.
+
+Using the @code{::} operator makes _GDBN__ search the scope
+specified by @var{scope} for the identifier @var{id}. If it is not
+found in the specified scope, then _GDBN__ will search all scopes
+enclosing the one specified by @var{scope}.
+
+Using the @code{.} operator makes _GDBN__ search the current scope for
+the identifier specified by @var{id} that was imported from the
+definition module specified by @var{module}. With this operator, it is
+an error if the identifier @var{id} was not imported from definition
+module @var{module}, or if @var{id} is not an identifier in
+@var{module}.
+
+@node GDB/M2, , M2 Scope, Modula-2
+@subsubsection _GDBN__ and Modula-2
+
+Some _GDBN__ commands have little use when debugging Modula-2 programs.
+Five subcommands of @code{set print} and @code{show print} apply
+specifically to C and C++: @samp{vtbl}, @samp{demangle},
+@samp{asm-demangle}, @samp{object}, and @samp{union}. The first four
+apply to C++, and the last to C's @code{union} type, which has no direct
+analogue in Modula-2.
+
+The @code{@@} operator (@pxref{Expressions, ,Expressions}), while available
+while using any language, is not useful with Modula-2. Its
+intent is to aid the debugging of @dfn{dynamic arrays}, which cannot be
+created in Modula-2 as they can in C or C++. However, because an
+address can be specified by an integral constant, the construct
+@samp{@{@var{type}@}@var{adrexp}} is still useful. (@pxref{Expressions, ,Expressions})
+_0__
+@cindex @code{#} in Modula-2
+In _GDBN__ scripts, the Modula-2 inequality operator @code{#} is
+interpreted as the beginning of a comment. Use @code{<>} instead.
+_1__
+@node Symbols, Altering, Languages, Top
+@chapter Examining the Symbol Table
+
+The commands described in this section allow you to inquire about the
+symbols (names of variables, functions and types) defined in your
+program. This information is inherent in the text of your program and
+does not change as your program executes. _GDBN__ finds it in your
+program's symbol table, in the file indicated when you started _GDBN__
+(@pxref{File Options, ,Choosing Files}), or by one of the
+file-management commands (@pxref{Files, ,Commands to Specify Files}).
+
+@table @code
+@item info address @var{symbol}
+@kindex info address
+Describe where the data for @var{symbol} is stored. For a register
+variable, this says which register it is kept in. For a non-register
+local variable, this prints the stack-frame offset at which the variable
+is always stored.
+
+Note the contrast with @samp{print &@var{symbol}}, which does not work
+at all for a register variables, and for a stack local variable prints
+the exact address of the current instantiation of the variable.
+
+@item whatis @var{exp}
+@kindex whatis
+Print the data type of expression @var{exp}. @var{exp} is not
+actually evaluated, and any side-effecting operations (such as
+assignments or function calls) inside it do not take place.
+@xref{Expressions, ,Expressions}.
+
+@item whatis
+Print the data type of @code{$}, the last value in the value history.
+
+@item ptype @var{typename}
+@kindex ptype
+Print a description of data type @var{typename}. @var{typename} may be
+the name of a type, or for C code it may have the form
+@samp{struct @var{struct-tag}}, @samp{union @var{union-tag}} or
+@samp{enum @var{enum-tag}}.
+
+@item ptype @var{exp}
+@itemx ptype
+Print a description of the type of expression @var{exp}. @code{ptype}
+differs from @code{whatis} by printing a detailed description, instead
+of just the name of the type. For example, if your program declares a
+variable as
+
+@example
+struct complex @{double real; double imag;@} v;
+@end example
+
+@noindent
+compare the output of the two commands:
+
+@example
+@group
+(_GDBP__) whatis v
+type = struct complex
+(_GDBP__) ptype v
+type = struct complex @{
+ double real;
+ double imag;
+@}
+@end group
+@end example
+
+@noindent
+As with @code{whatis}, using @code{ptype} without an argument refers to
+the type of @code{$}, the last value in the value history.
+
+@item info types @var{regexp}
+@itemx info types
+@kindex info types
+Print a brief description of all types whose name matches @var{regexp}
+(or all types in your program, if you supply no argument). Each
+complete typename is matched as though it were a complete line; thus,
+@samp{i type value} gives information on all types in your program whose
+name includes the string @code{value}, but @samp{i type ^value$} gives
+information only on types whose complete name is @code{value}.
+
+This command differs from @code{ptype} in two ways: first, like
+@code{whatis}, it does not print a detailed description; second, it
+lists all source files where a type is defined.
+
+@item info source
+@kindex info source
+Show the name of the current source file---that is, the source file for
+the function containing the current point of execution---and the language
+it was written in.
+
+@item info sources
+@kindex info sources
+Print the names of all source files in your program for which there is
+debugging information, organized into two lists: files whose symbols
+have already been read, and files whose symbols will be read when needed.
+
+@item info functions
+@kindex info functions
+Print the names and data types of all defined functions.
+
+@item info functions @var{regexp}
+Print the names and data types of all defined functions
+whose names contain a match for regular expression @var{regexp}.
+Thus, @samp{info fun step} finds all functions whose names
+include @code{step}; @samp{info fun ^step} finds those whose names
+start with @code{step}.
+
+@item info variables
+@kindex info variables
+Print the names and data types of all variables that are declared
+outside of functions (i.e., excluding local variables).
+
+@item info variables @var{regexp}
+Print the names and data types of all variables (except for local
+variables) whose names contain a match for regular expression
+@var{regexp}.
+
+@ignore
+This was never implemented.
+@item info methods
+@itemx info methods @var{regexp}
+@kindex info methods
+The @code{info methods} command permits the user to examine all defined
+methods within C++ program, or (with the @var{regexp} argument) a
+specific set of methods found in the various C++ classes. Many
+C++ classes provide a large number of methods. Thus, the output
+from the @code{ptype} command can be overwhelming and hard to use. The
+@code{info-methods} command filters the methods, printing only those
+which match the regular-expression @var{regexp}.
+@end ignore
+
+@item printsyms @var{filename}
+@itemx printpsyms @var{filename}
+@itemx printmsyms @var{filename}
+@kindex printsyms
+@cindex symbol dump
+@kindex printsyms
+@cindex partial symbol dump
+Write a dump of debugging symbol data into the file @var{filename}.
+These commands are used to debug the _GDBN__ symbol-reading code. Only
+symbols with debugging data are included. If you use @code{printsyms},
+_GDBN__ includes all the symbols for which it has already collected full
+details: that is, @var{filename} reflects symbols for only those files
+whose symbols _GDBN__ has read. You can use the command @code{info
+sources} to find out which files these are. If you use
+@code{printpsyms} instead, the dump shows information about symbols that
+_GDBN__ only knows partially---that is, symbols defined in files that
+_GDBN__ has skimmed, but not yet read completely. Finally,
+@code{printmsyms} dumps just the minimal symbol information required for
+each object file from which _GDBN__ has read some symbols. The description of
+@code{symbol-file} explains how _GDBN__ reads symbols; both @code{info
+source} and @code{symbol-file} are described in @ref{Files, ,Commands
+to Specify Files}.
+@end table
+
+@node Altering, _GDBN__ Files, Symbols, Top
+@chapter Altering Execution
+
+Once you think you have found an error in your program, you might want to
+find out for certain whether correcting the apparent error would lead to
+correct results in the rest of the run. You can find the answer by
+experiment, using the _GDBN__ features for altering execution of the
+program.
+
+For example, you can store new values into variables or memory
+locations, give your program a signal, restart it at a different address,
+or even return prematurely from a function to its caller.
+
+@menu
+* Assignment:: Assignment to Variables
+* Jumping:: Continuing at a Different Address
+* Signaling:: Giving your program a Signal
+* Returning:: Returning from a Function
+* Calling:: Calling your Program's Functions
+* Patching:: Patching your Program
+@end menu
+
+@node Assignment, Jumping, Altering, Altering
+@section Assignment to Variables
@cindex assignment
@cindex setting variables
To alter the value of a variable, evaluate an assignment expression.
-@xref{Expressions}. For example,
+@xref{Expressions, ,Expressions}. For example,
+
+@example
+print x=4
+@end example
+
+@noindent
+stores the value 4 into the variable @code{x}, and then prints the
+value of the assignment expression (which is 4). @xref{Languages,
+,Using _GDBN__ with Different Languages}, for more information on
+operators in supported languages.
+
+@kindex set variable
+@cindex variables, setting
+If you are not interested in seeing the value of the assignment, use the
+@code{set} command instead of the @code{print} command. @code{set} is
+really the same as @code{print} except that the expression's value is not
+printed and is not put in the value history (@pxref{Value History, ,Value History}). The
+expression is evaluated only for its effects.
+
+If the beginning of the argument string of the @code{set} command
+appears identical to a @code{set} subcommand, use the @code{set
+variable} command instead of just @code{set}. This command is identical
+to @code{set} except for its lack of subcommands. For example, a
+program might well have a variable @code{width}---which leads to
+an error if we try to set a new value with just @samp{set width=13}, as
+we might if @code{set width} did not happen to be a _GDBN__ command:
+
+@example
+(_GDBP__) whatis width
+type = double
+(_GDBP__) p width
+$4 = 13
+(_GDBP__) set width=47
+Invalid syntax in expression.
+@end example
+
+@noindent
+The invalid expression, of course, is @samp{=47}. What we can do in
+order to actually set our program's variable @code{width} is
+
+@example
+(_GDBP__) set var width=47
+@end example
+
+_GDBN__ allows more implicit conversions in assignments than C; you can
+freely store an integer value into a pointer variable or vice versa,
+and any structure can be converted to any other structure that is the
+same length or shorter.
+@comment FIXME: how do structs align/pad in these conversions?
+
+To store values into arbitrary places in memory, use the @samp{@{@dots{}@}}
+construct to generate a value of specified type at a specified address
+(@pxref{Expressions, ,Expressions}). For example, @code{@{int@}0x83040} refers
+to memory location @code{0x83040} as an integer (which implies a certain size
+and representation in memory), and
+
+@example
+set @{int@}0x83040 = 4
+@end example
+
+@noindent
+stores the value 4 into that memory location.
+
+@node Jumping, Signaling, Assignment, Altering
+@section Continuing at a Different Address
+
+Ordinarily, when you continue your program, you do so at the place where
+it stopped, with the @code{continue} command. You can instead continue at
+an address of your own choosing, with the following commands:
+
+@table @code
+@item jump @var{linespec}
+@kindex jump
+Resume execution at line @var{linespec}. Execution will stop
+immediately if there is a breakpoint there. @xref{List, ,Printing
+Source Lines}, for a description of the different forms of
+@var{linespec}.
+
+The @code{jump} command does not change the current stack frame, or
+the stack pointer, or the contents of any memory location or any
+register other than the program counter. If line @var{linespec} is in
+a different function from the one currently executing, the results may
+be bizarre if the two functions expect different patterns of arguments or
+of local variables. For this reason, the @code{jump} command requests
+confirmation if the specified line is not in the function currently
+executing. However, even bizarre results are predictable if you are
+well acquainted with the machine-language code of your program.
+
+@item jump *@var{address}
+Resume execution at the instruction at address @var{address}.
+@end table
+
+You can get much the same effect as the @code{jump} command by storing a
+new value into the register @code{$pc}. The difference is that this
+does not start your program running; it only changes the address where it
+@emph{will} run when it is continued. For example,
+
+@example
+set $pc = 0x485
+@end example
+
+@noindent
+causes the next @code{continue} command or stepping command to execute at
+address @code{0x485}, rather than at the address where your program stopped.
+@xref{Continuing and Stepping, ,Continuing and Stepping}.
+
+The most common occasion to use the @code{jump} command is to back up,
+perhaps with more breakpoints set, over a portion of a program that has
+already executed, in order to examine its execution in more detail.
+
+@node Signaling, Returning, Jumping, Altering
+@c @group
+@section Giving your program a Signal
+
+@table @code
+@item signal @var{signalnum}
+@kindex signal
+Resume execution where your program stopped, but give it immediately the
+signal number @var{signalnum}.
+
+Alternatively, if @var{signalnum} is zero, continue execution without
+giving a signal. This is useful when your program stopped on account of
+a signal and would ordinary see the signal when resumed with the
+@code{continue} command; @samp{signal 0} causes it to resume without a
+signal.
+
+@code{signal} does not repeat when you press @key{RET} a second time
+after executing the command.
+@end table
+@c @end group
+
+@node Returning, Calling, Signaling, Altering
+@section Returning from a Function
+
+@table @code
+@item return
+@itemx return @var{expression}
+@cindex returning from a function
+@kindex return
+You can cancel execution of a function call with the @code{return}
+command. If you give an
+@var{expression} argument, its value is used as the function's return
+value.
+@end table
+
+When you use @code{return}, _GDBN__ discards the selected stack frame
+(and all frames within it). You can think of this as making the
+discarded frame return prematurely. If you wish to specify a value to
+be returned, give that value as the argument to @code{return}.
+
+This pops the selected stack frame (@pxref{Selection, ,Selecting a
+Frame}), and any other frames inside of it, leaving its caller as the
+innermost remaining frame. That frame becomes selected. The
+specified value is stored in the registers used for returning values
+of functions.
+
+The @code{return} command does not resume execution; it leaves the
+program stopped in the state that would exist if the function had just
+returned. In contrast, the @code{finish} command (@pxref{Continuing
+and Stepping, ,Continuing and Stepping}) resumes execution until the
+selected stack frame returns naturally.
+
+@node Calling, Patching, Returning, Altering
+@section Calling your Program's Functions
+
+@cindex calling functions
+@kindex call
+@table @code
+@item call @var{expr}
+Evaluate the expression @var{expr} without displaying @code{void}
+returned values.
+@end table
+
+You can use this variant of the @code{print} command if you want to
+execute a function from your program, but without cluttering the output
+with @code{void} returned values. The result is printed and saved in
+the value history, if it is not void.
+
+@node Patching, , Calling, Altering
+@section Patching your Program
+@cindex patching binaries
+@cindex writing into executables
+@cindex writing into corefiles
+
+By default, _GDBN__ opens the file containing your program's executable
+code (or the corefile) read-only. This prevents accidental alterations
+to machine code; but it also prevents you from intentionally patching
+your program's binary.
+
+If you'd like to be able to patch the binary, you can specify that
+explicitly with the @code{set write} command. For example, you might
+want to turn on internal debugging flags, or even to make emergency
+repairs.
+
+@table @code
+@item set write on
+@itemx set write off
+@kindex set write
+If you specify @samp{set write on}, _GDBN__ will open executable and
+core files for both reading and writing; if you specify @samp{set write
+off} (the default), _GDBN__ will open them read-only.
+
+If you have already loaded a file, you must load it
+again (using the @code{exec-file} or @code{core-file} command) after
+changing @code{set write}, for your new setting to take effect.
+
+@item show write
+@kindex show write
+Display whether executable files and core files will be opened for
+writing as well as reading.
+@end table
+
+@node _GDBN__ Files, Targets, Altering, Top
+@chapter _GDBN__'s Files
+
+_GDBN__ needs to know the file name of the program to be debugged, both in
+order to read its symbol table and in order to start your program. To
+debug a core dump of a previous run, _GDBN__ must be told the file name of
+the core dump.
+
+@menu
+* Files:: Commands to Specify Files
+* Symbol Errors:: Errors Reading Symbol Files
+@end menu
+
+@node Files, Symbol Errors, _GDBN__ Files, _GDBN__ Files
+@section Commands to Specify Files
+@cindex core dump file
+@cindex symbol table
+
+The usual way to specify executable and core dump file names is with
+the command arguments given when you start _GDBN__, (@pxref{Invocation,
+,Getting In and Out of _GDBN__}.
+
+Occasionally it is necessary to change to a different file during a
+_GDBN__ session. Or you may run _GDBN__ and forget to specify the files you
+want to use. In these situations the _GDBN__ commands to specify new files
+are useful.
+
+@table @code
+@item file @var{filename}
+@cindex executable file
+@kindex file
+Use @var{filename} as the program to be debugged. It is read for its
+symbols and for the contents of pure memory. It is also the program
+executed when you use the @code{run} command. If you do not specify a
+directory and the file is not found in _GDBN__'s working directory, _GDBN__
+uses the environment variable @code{PATH} as a list of directories to
+search, just as the shell does when looking for a program to run. You
+can change the value of this variable, for both _GDBN__ and your program,
+using the @code{path} command.
+
+On systems with memory-mapped files, an auxiliary symbol table file
+@file{@var{filename}.syms} may be available for @var{filename}. If it
+is, _GDBN__ will map in the symbol table from
+@file{@var{filename}.syms}, starting up more quickly. See the
+descriptions of the options @samp{-mapped} and @samp{-readnow} (available
+on the command line, and with the commands @code{file}, @code{symbol-file},
+or @code{add-symbol-file}), for more information.
+
+@item file
+@code{file} with no argument makes _GDBN__ discard any information it
+has on both executable file and the symbol table.
+
+@item exec-file @r{[} @var{filename} @r{]}
+@kindex exec-file
+Specify that the program to be run (but not the symbol table) is found
+in @var{filename}. _GDBN__ will search the environment variable @code{PATH}
+if necessary to locate your program. Omitting @var{filename} means to
+discard information on the executable file.
+
+@item symbol-file @r{[} @var{filename} @r{]}
+@kindex symbol-file
+Read symbol table information from file @var{filename}. @code{PATH} is
+searched when necessary. Use the @code{file} command to get both symbol
+table and program to run from the same file.
+
+@code{symbol-file} with no argument clears out _GDBN__'s information on your
+program's symbol table.
+
+The @code{symbol-file} command causes _GDBN__ to forget the contents of its
+convenience variables, the value history, and all breakpoints and
+auto-display expressions. This is because they may contain pointers to
+the internal data recording symbols and data types, which are part of
+the old symbol table data being discarded inside _GDBN__.
+
+@code{symbol-file} will not repeat if you press @key{RET} again after
+executing it once.
+
+When _GDBN__ is configured for a particular environment, it will
+understand debugging information in whatever format is the standard
+generated for that environment; you may use either a GNU compiler, or
+other compilers that adhere to the local conventions. Best results are
+usually obtained from GNU compilers; for example, using @code{_GCC__}
+you can generate debugging information for optimized code.
+
+On some kinds of object files, the @code{symbol-file} command does not
+normally read the symbol table in full right away. Instead, it scans
+the symbol table quickly to find which source files and which symbols
+are present. The details are read later, one source file at a time,
+as they are needed.
+
+The purpose of this two-stage reading strategy is to make _GDBN__ start up
+faster. For the most part, it is invisible except for occasional
+pauses while the symbol table details for a particular source file are
+being read. (The @code{set verbose} command can turn these pauses
+into messages if desired. @xref{Messages/Warnings, ,Optional Warnings
+and Messages}.)
+
+When the symbol table is stored in COFF format, @code{symbol-file} does
+read the symbol table data in full right away. We have not implemented
+the two-stage strategy for COFF yet.
+
+@item symbol-file @var{filename} @r{[} -readnow @r{]} @r{[} -mapped @r{]}
+@itemx file @var{filename} @r{[} -readnow @r{]} @r{[} -mapped @r{]}
+@kindex readnow
+@cindex reading symbols immediately
+@cindex symbols, reading immediately
+@kindex mapped
+@cindex memory-mapped symbol file
+@cindex saving symbol table
+You can override the _GDBN__ two-stage strategy for reading symbol
+tables by using the @samp{-readnow} option with any of the commands that
+load symbol table information, if you want to be sure _GDBN__ has the
+entire symbol table available.
+
+If memory-mapped files are available on your system through the
+@code{mmap} system call, you can use another option, @samp{-mapped}, to
+cause _GDBN__ to write the symbols for your program into a reusable
+file. Future _GDBN__ debugging sessions will map in symbol information
+from this auxiliary symbol file (if the program hasn't changed), rather
+than spending time reading the symbol table from the executable
+program. Using the @samp{-mapped} option has the same effect as
+starting _GDBN__ with the @samp{-mapped} command-line option.
+
+You can use both options together, to make sure the auxiliary symbol
+file has all the symbol information for your program.
+
+The @code{.syms} file is specific to the host machine on which GDB is run.
+It holds an exact image of GDB's internal symbol table. It cannot be
+shared across multiple host platforms.
+
+The auxiliary symbol file for a program called @var{myprog} is called
+@samp{@var{myprog}.syms}. Once this file exists (so long as it is newer
+than the corresponding executable), _GDBN__ will always attempt to use
+it when you debug @var{myprog}; no special options or commands are
+needed.
+@c FIXME: for now no mention of directories, since this seems to be in
+@c flux. 13mar1992 status is that in theory GDB would look either in
+@c current dir or in same dir as myprog; but issues like competing
+@c GDB's, or clutter in system dirs, mean that in practice right now
+@c only current dir is used. FFish says maybe a special GDB hierarchy
+@c (eg rooted in val of env var GDBSYMS) could exist for mappable symbol
+@c files.
+
+@item core-file @r{[} @var{filename} @r{]}
+@kindex core
+@kindex core-file
+Specify the whereabouts of a core dump file to be used as the ``contents
+of memory''. Traditionally, core files contain only some parts of the
+address space of the process that generated them; _GDBN__ can access the
+executable file itself for other parts.
+
+@code{core-file} with no argument specifies that no core file is
+to be used.
+
+Note that the core file is ignored when your program is actually running
+under _GDBN__. So, if you have been running your program and you wish to
+debug a core file instead, you must kill the subprocess in which the
+program is running. To do this, use the @code{kill} command
+(@pxref{Kill Process, ,Killing the Child Process}).
+
+@item load @var{filename}
+@kindex load
+_if__(_GENERIC__)
+Depending on what remote debugging facilities are configured into
+_GDBN__, the @code{load} command may be available. Where it exists, it
+is meant to make @var{filename} (an executable) available for debugging
+on the remote system---by downloading, or dynamic linking, for example.
+@code{load} also records @var{filename}'s symbol table in _GDBN__, like
+the @code{add-symbol-file} command.
+
+If @code{load} is not available on your _GDBN__, attempting to execute
+it gets the error message ``@code{You can't do that when your target is
+@dots{}}''
+_fi__(_GENERIC__)
+
+_if__(_VXWORKS__)
+On VxWorks, @code{load} will dynamically link @var{filename} on the
+current target system as well as adding its symbols in _GDBN__.
+_fi__(_VXWORKS__)
+
+_if__(_I960__)
+@cindex download to Nindy-960
+With the Nindy interface to an Intel 960 board, @code{load} will
+download @var{filename} to the 960 as well as adding its symbols in
+_GDBN__.
+_fi__(_I960__)
+
+_if__(_H8__)
+@cindex download to H8/300
+@cindex H8/300 download
+When you select remote debugging to a Hitachi H8/300 board (@pxref{Hitachi
+H8/300 Remote,,_GDBN__ and the Hitachi H8/300}), the
+@code{load} command downloads your program to the H8/300 and also opens
+it as the current executable target for _GDBN__ on your host (like the
+@code{file} command).
+_fi__(_H8__)
+
+@code{load} will not repeat if you press @key{RET} again after using it.
+
+@item add-symbol-file @var{filename} @var{address}
+@itemx add-symbol-file @var{filename} @var{address} @r{[} -readnow @r{]} @r{[} -mapped @r{]}
+@kindex add-symbol-file
+@cindex dynamic linking
+The @code{add-symbol-file} command reads additional symbol table information
+from the file @var{filename}. You would use this command when @var{filename}
+has been dynamically loaded (by some other means) into the program that
+is running. @var{address} should be the memory address at which the
+file has been loaded; _GDBN__ cannot figure this out for itself.
+
+The symbol table of the file @var{filename} is added to the symbol table
+originally read with the @code{symbol-file} command. You can use the
+@code{add-symbol-file} command any number of times; the new symbol data thus
+read keeps adding to the old. To discard all old symbol data instead,
+use the @code{symbol-file} command.
+
+@code{add-symbol-file} will not repeat if you press @key{RET} after using it.
+
+You can use the @samp{-mapped} and @samp{-readnow} options just as with
+the @code{symbol-file} command, to change how _GDBN__ manages the symbol
+tabl einformation for @var{filename}.
+
+@item info files
+@itemx info target
+@kindex info files
+@kindex info target
+@code{info files} and @code{info target} are synonymous; both print
+the current targets (@pxref{Targets, ,Specifying a Debugging Target}),
+including the names of the executable and core dump files currently in
+use by _GDBN__, and the files from which symbols were loaded. The command
+@code{help targets} lists all possible targets rather than current
+ones.
+
+@end table
+
+All file-specifying commands allow both absolute and relative file names
+as arguments. _GDBN__ always converts the file name to an absolute path
+name and remembers it that way.
+
+@cindex shared libraries
+
+_GDBN__ supports SunOS, SVR4, and IBM RS/6000 shared libraries.
+_GDBN__ automatically loads symbol definitions from shared libraries
+when you use the @code{run} command, or when you examine a core file.
+(Before you issue the @code{run} command, _GDBN__ will not understand
+references to a function in a shared library, however---unless you are
+debugging a core file).
+@c FIXME: next _GDBN__ release should permit some refs to undef
+@c FIXME...symbols---eg in a break cmd---assuming they are from a shared lib
+
+@table @code
+@item info share
+@itemx info sharedlibrary
+@kindex info sharedlibrary
+@kindex info share
+Print the names of the shared libraries which are currently loaded.
+
+@item sharedlibrary @var{regex}
+@itemx share @var{regex}
+@kindex sharedlibrary
+@kindex share
+This is an obsolescent command; you can use it to explicitly
+load shared object library symbols for files matching a UNIX regular
+expression, but as with files loaded automatically, it will only load
+shared libraries required by your program for a core file or after
+typing @code{run}. If @var{regex} is omitted all shared libraries
+required by your program are loaded.
+@end table
+
+@node Symbol Errors, , Files, _GDBN__ Files
+@section Errors Reading Symbol Files
+
+While reading a symbol file, _GDBN__ will occasionally encounter problems,
+such as symbol types it does not recognize, or known bugs in compiler
+output. By default, _GDBN__ does not notify you of such problems, since
+they are relatively common and primarily of interest to people
+debugging compilers. If you are interested in seeing information
+about ill-constructed symbol tables, you can either ask _GDBN__ to print
+only one message about each such type of problem, no matter how many
+times the problem occurs; or you can ask _GDBN__ to print more messages,
+to see how many times the problems occur, with the @code{set
+complaints} command (@pxref{Messages/Warnings, ,Optional Warnings and
+Messages}).
+
+The messages currently printed, and their meanings, are:
+
+@table @code
+@item inner block not inside outer block in @var{symbol}
+
+The symbol information shows where symbol scopes begin and end
+(such as at the start of a function or a block of statements). This
+error indicates that an inner scope block is not fully contained
+in its outer scope blocks.
+
+_GDBN__ circumvents the problem by treating the inner block as if it had
+the same scope as the outer block. In the error message, @var{symbol}
+may be shown as ``@code{(don't know)}'' if the outer block is not a
+function.
+
+@item block at @var{address} out of order
+
+The symbol information for symbol scope blocks should occur in
+order of increasing addresses. This error indicates that it does not
+do so.
+
+_GDBN__ does not circumvent this problem, and will have trouble locating
+symbols in the source file whose symbols being read. (You can often
+determine what source file is affected by specifying @code{set verbose
+on}. @xref{Messages/Warnings, ,Optional Warnings and Messages}.)
+
+@item bad block start address patched
+
+The symbol information for a symbol scope block has a start address
+smaller than the address of the preceding source line. This is known
+to occur in the SunOS 4.1.1 (and earlier) C compiler.
+
+_GDBN__ circumvents the problem by treating the symbol scope block as
+starting on the previous source line.
+
+@item bad string table offset in symbol @var{n}
+
+@cindex foo
+Symbol number @var{n} contains a pointer into the string table which is
+larger than the size of the string table.
+
+_GDBN__ circumvents the problem by considering the symbol to have the
+name @code{foo}, which may cause other problems if many symbols end up
+with this name.
+
+@item unknown symbol type @code{0x@var{nn}}
+
+The symbol information contains new data types that _GDBN__ does not yet
+know how to read. @code{0x@var{nn}} is the symbol type of the misunderstood
+information, in hexadecimal.
+
+_GDBN__ circumvents the error by ignoring this symbol information. This
+will usually allow your program to be debugged, though certain symbols
+will not be accessible. If you encounter such a problem and feel like
+debugging it, you can debug @code{_GDBP__} with itself, breakpoint on
+@code{complain}, then go up to the function @code{read_dbx_symtab} and
+examine @code{*bufp} to see the symbol.
+
+@item stub type has NULL name
+_GDBN__ could not find the full definition for a struct or class.
+
+@item const/volatile indicator missing (ok if using g++ v1.x), got@dots{}
+
+The symbol information for a C++ member function is missing some
+information that recent versions of the compiler should have output
+for it.
+
+@item info mismatch between compiler and debugger
+
+_GDBN__ could not parse a type specification output by the compiler.
+@end table
+
+@node Targets, Controlling _GDBN__, _GDBN__ Files, Top
+@chapter Specifying a Debugging Target
+@cindex debugging target
+@kindex target
+
+A @dfn{target} is the execution environment occupied by your program.
+Often, _GDBN__ runs in the same host environment as your program; in
+that case, the debugging target is specified as a side effect when you
+use the @code{file} or @code{core} commands. When you need more
+flexibility---for example, running _GDBN__ on a physically separate
+host, or controlling a standalone system over a serial port or a
+realtime system over a TCP/IP connection---you can use the @code{target}
+command to specify one of the target types configured for _GDBN__
+(@pxref{Target Commands, ,Commands for Managing Targets}).
+
+@menu
+* Active Targets:: Active Targets
+* Target Commands:: Commands for Managing Targets
+* Remote:: Remote Debugging
+@end menu
+
+@node Active Targets, Target Commands, Targets, Targets
+@section Active Targets
+@cindex stacking targets
+@cindex active targets
+@cindex multiple targets
+
+There are three classes of targets: processes, core files, and
+executable files. _GDBN__ can work concurrently on up to three active
+targets, one in each class. This allows you to (for example) start a
+process and inspect its activity without abandoning your work on a core
+file.
+
+If, for example, you execute @samp{gdb a.out}, then the executable file
+@code{a.out} is the only active target. If you designate a core file as
+well---presumably from a prior run that crashed and coredumped---then
+_GDBN__ has two active targets and will use them in tandem, looking
+first in the corefile target, then in the executable file, to satisfy
+requests for memory addresses. (Typically, these two classes of target
+are complementary, since core files contain only a program's
+read-write memory---variables and so on---plus machine status, while
+executable files contain only the program text and initialized data.)
+
+When you type @code{run}, your executable file becomes an active process
+target as well. When a process target is active, all _GDBN__ commands
+requesting memory addresses refer to that target; addresses in an active
+core file or executable file target are obscured while the process
+target is active.
+
+Use the @code{core-file} and @code{exec-file} commands to select a
+new core file or executable target (@pxref{Files, ,Commands to Specify
+Files}). To specify as a target a process that is already running, use
+the @code{attach} command (@pxref{Attach, ,Debugging an
+Already-Running Process}.).
+
+@node Target Commands, Remote, Active Targets, Targets
+@section Commands for Managing Targets
+
+@table @code
+@item target @var{type} @var{parameters}
+Connects the _GDBN__ host environment to a target machine or process. A
+target is typically a protocol for talking to debugging facilities. You
+use the argument @var{type} to specify the type or protocol of the
+target machine.
+
+Further @var{parameters} are interpreted by the target protocol, but
+typically include things like device names or host names to connect
+with, process numbers, and baud rates.
+
+The @code{target} command will not repeat if you press @key{RET} again
+after executing the command.
+
+@item help target
+@kindex help target
+Displays the names of all targets available. To display targets
+currently selected, use either @code{info target} or @code{info files}
+(@pxref{Files, ,Commands to Specify Files}).
+
+@item help target @var{name}
+Describe a particular target, including any parameters necessary to
+select it.
+@end table
+
+Here are some common targets (available, or not, depending on the GDB
+configuration):
+
+@table @code
+@item target exec @var{prog}
+@kindex target exec
+An executable file. @samp{target exec @var{prog}} is the same as
+@samp{exec-file @var{prog}}.
+
+@item target core @var{filename}
+@kindex target core
+A core dump file. @samp{target core @var{filename}} is the same as
+@samp{core-file @var{filename}}.
+
+@item target remote @var{dev}
+@kindex target remote
+Remote serial target in GDB-specific protocol. The argument @var{dev}
+specifies what serial device to use for the connection (e.g.
+@file{/dev/ttya}). @xref{Remote, ,Remote Debugging}.
+
+_if__(_AMD29K__)
+@item target amd-eb @var{dev} @var{speed} @var{PROG}
+@kindex target amd-eb
+@cindex AMD EB29K
+Remote PC-resident AMD EB29K board, attached over serial lines.
+@var{dev} is the serial device, as for @code{target remote};
+@var{speed} allows you to specify the linespeed; and @var{PROG} is the
+name of the program to be debugged, as it appears to DOS on the PC.
+@xref{EB29K Remote, ,GDB with a Remote EB29K}.
+
+_fi__(_AMD29K__)
+_if__(_H8__)
+@item target hms
+@kindex target hms
+A Hitachi H8/300 board, attached via serial line to your host. Use
+special commands @code{device} and @code{speed} to control the serial
+line and the communications speed used. @xref{Hitachi H8/300
+Remote,,_GDBN__ and the Hitachi H8/300}.
+
+_fi__(_H8__)
+_if__(_I960__)
+@item target nindy @var{devicename}
+@kindex target nindy
+An Intel 960 board controlled by a Nindy Monitor. @var{devicename} is
+the name of the serial device to use for the connection, e.g.
+@file{/dev/ttya}. @xref{i960-Nindy Remote, ,_GDBN__ with a Remote i960 (Nindy)}.
+
+_fi__(_I960__)
+_if__(_VXWORKS__)
+@item target vxworks @var{machinename}
+@kindex target vxworks
+A VxWorks system, attached via TCP/IP. The argument @var{machinename}
+is the target system's machine name or IP address.
+@xref{VxWorks Remote, ,_GDBN__ and VxWorks}.
+_fi__(_VXWORKS__)
+@end table
+
+_if__(_GENERIC__)
+Different targets are available on different configurations of _GDBN__; your
+configuration may have more or fewer targets.
+_fi__(_GENERIC__)
+
+@node Remote, , Target Commands, Targets
+@section Remote Debugging
+@cindex remote debugging
+
+If you are trying to debug a program running on a machine that cannot run
+GDB in the usual way, it is often useful to use remote debugging. For
+example, you might use remote debugging on an operating system kernel, or on
+a small system which does not have a general purpose operating system
+powerful enough to run a full-featured debugger.
+
+Some configurations of GDB have special serial or TCP/IP interfaces
+to make this work with particular debugging targets. In addition,
+GDB comes with a generic serial protocol (specific to GDB, but
+not specific to any particular target system) which you can use if you
+write the remote stubs---the code that will run on the remote system to
+communicate with GDB.
+
+To use the GDB remote serial protocol, the program to be debugged on
+the remote machine needs to contain a debugging stub which talks to
+GDB over the serial line. Several working remote stubs are
+distributed with GDB; see the @file{README} file in the GDB
+distribution for more information.
+
+For details of this communication protocol, see the comments in the
+GDB source file @file{remote.c}.
+
+To start remote debugging, first run GDB and specify as an executable file
+the program that is running in the remote machine. This tells GDB how
+to find your program's symbols and the contents of its pure text. Then
+establish communication using the @code{target remote} command with a device
+name as an argument. For example:
@example
-print x=4
+target remote /dev/ttyb
@end example
@noindent
-would store the value 4 into the variable @code{x}, and then print
-the value of the assignment expression (which is 4).
+if the serial line is connected to the device named @file{/dev/ttyb}. This
+will stop the remote machine if it is not already stopped.
-All the assignment operators of C are supported, including the
-increment operators @samp{++} and @samp{--}, and combining
-assignments such as @samp{+=} and @samp{<<=}.
+Now you can use all the usual commands to examine and change data and to
+step and continue the remote program.
-@kindex set
-@kindex set variable
-@cindex variables, setting
-If you are not interested in seeing the value of the assignment, use the
-@samp{set} command instead of the @samp{print} command. @samp{set} is
-really the same as @samp{print} except that the expression's value is not
-printed and is not put in the value history (@pxref{Value History}). The
-expression is evaluated only for side effects.
-
-Note that if the beginning of the argument string of the @samp{set} command
-appears identical to a @samp{set} subcommand, it may be necessary to use
-the @samp{set variable} command. This command is identical to @samp{set}
-except for its lack of subcommands.
-
-_GDBN__ allows more implicit conversions in assignments than C does; you can
-freely store an integer value into a pointer variable or vice versa, and
-any structure can be converted to any other structure that is the same
-length or shorter.
-@comment FIXME: how do structs align/pad in these conversions?
+To resume the remote program and stop debugging it, use the @code{detach}
+command.
-To store values into arbitrary places in memory, use the @samp{@{@dots{}@}}
-construct to generate a value of specified type at a specified address
-(@pxref{Expressions}). For example, @code{@{int@}0x83040} would refer
-to memory location 0x83040 as an integer (which implies a certain size
-and representation in memory), and
+@kindex set remotedebug
+@kindex show remotedebug
+@cindex packets, reporting on stdout
+@cindex serial connections, debugging
+If you have trouble with the serial connection, you can use the command
+@code{set remotedebug}. This makes _GDBN__ report on all packets sent
+back and forth across the serial line to the remote machine. The
+packet-debugging information is printed on the _GDBN__ standard output
+stream. @code{set remotedebug off} turns it off, and @code{show
+remotedebug} will show you its current state.
-@example
-set @{int@}0x83040 = 4
-@end example
+Other remote targets may be available in your
+configuration of GDB; use @code{help targets} to list them.
+
+_if__(_GENERIC__)
+_dnl__ Text on starting up GDB in various specific cases; it goes up front
+_dnl__ in manuals configured for any of those particular situations, here
+_dnl__ otherwise.
+@menu
+_include__(gdbinv-m.m4)<>_dnl__
+@end menu
+_include__(gdbinv-s.m4)
+_fi__(_GENERIC__)
-would store the value 4 into that memory location.
+@node Controlling _GDBN__, Sequences, Targets, Top
+@chapter Controlling _GDBN__
-@node Jumping, Signaling, Assignment, Altering
-@section Continuing at a Different Address
+You can alter many aspects of _GDBN__'s interaction with you by using
+the @code{set} command. For commands controlling how _GDBN__ displays
+data, @pxref{Print Settings, ,Print Settings}; other settings are described here.
-Ordinarily, when you continue the program, you do so at the place where
-it stopped, with the @samp{cont} command. You can instead continue at
-an address of your own choosing, with the following commands:
+@menu
+* Prompt:: Prompt
+* Editing:: Command Editing
+* History:: Command History
+* Screen Size:: Screen Size
+* Numbers:: Numbers
+* Messages/Warnings:: Optional Warnings and Messages
+@end menu
+
+@node Prompt, Editing, Controlling _GDBN__, Controlling _GDBN__
+@section Prompt
+@cindex prompt
+
+_GDBN__ indicates its readiness to read a command by printing a string
+called the @dfn{prompt}. This string is normally @samp{(_GDBP__)}. You
+can change the prompt string with the @code{set prompt} command. For
+instance, when debugging _GDBN__ with _GDBN__, it is useful to change
+the prompt in one of the _GDBN__<>s so that you can always tell which
+one you are talking to.
@table @code
-@item jump @var{linenum}
-@kindex jump
-Resume execution at line number @var{linenum}. Execution may stop
-immediately if there is a breakpoint there.
+@item set prompt @var{newprompt}
+@kindex set prompt
+Directs _GDBN__ to use @var{newprompt} as its prompt string henceforth.
+@kindex show prompt
+@item show prompt
+Prints a line of the form: @samp{Gdb's prompt is: @var{your-prompt}}
+@end table
-The @samp{jump} command does not change the current stack frame, or
-the stack pointer, or the contents of any memory location or any
-register other than the program counter. If line @var{linenum} is in
-a different function from the one currently executing, the results may
-be bizarre if the two functions expect different patterns of arguments or
-of local variables. For this reason, the @samp{jump} command requests
-confirmation if the specified line is not in the function currently
-executing. However, even bizarre results are predictable based on
-careful study of the machine-language code of the program.
+@node Editing, History, Prompt, Controlling _GDBN__
+@section Command Editing
+@cindex readline
+@cindex command line editing
-@item jump *@var{address}
-Resume execution at the instruction at address @var{address}.
+_GDBN__ reads its input commands via the @dfn{readline} interface. This
+GNU library provides consistent behavior for programs which provide a
+command line interface to the user. Advantages are @code{emacs}-style
+or @code{vi}-style inline editing of commands, @code{csh}-like history
+substitution, and a storage and recall of command history across
+debugging sessions.
+
+You may control the behavior of command line editing in _GDBN__ with the
+command @code{set}.
+
+@table @code
+@kindex set editing
+@cindex editing
+@item set editing
+@itemx set editing on
+Enable command line editing (enabled by default).
+
+@item set editing off
+Disable command line editing.
+
+@kindex show editing
+@item show editing
+Show whether command line editing is enabled.
@end table
-You can get much the same effect as the @code{jump} command by storing a
-new value into the register @code{$pc}. The difference is that this
-does not start the program running; it only changes the address where it
-@emph{will} run when it is continued. For example,
+@node History, Screen Size, Editing, Controlling _GDBN__
+@section Command History
+
+@table @code
+@cindex history substitution
+@cindex history file
+@kindex set history filename
+@item set history filename @var{fname}
+Set the name of the _GDBN__ command history file to @var{fname}. This is
+the file from which _GDBN__ will read an initial command history
+list or to which it will write this list when it exits. This list is
+accessed through history expansion or through the history
+command editing characters listed below. This file defaults to the
+value of the environment variable @code{GDBHISTFILE}, or to
+@file{./.gdb_history} if this variable is not set.
+
+@cindex history save
+@kindex set history save
+@item set history save
+@itemx set history save on
+Record command history in a file, whose name may be specified with the
+@code{set history filename} command. By default, this option is disabled.
+
+@item set history save off
+Stop recording command history in a file.
+
+@cindex history size
+@kindex set history size
+@item set history size @var{size}
+Set the number of commands which _GDBN__ will keep in its history list.
+This defaults to the value of the environment variable
+@code{HISTSIZE}, or to 256 if this variable is not set.
+@end table
+
+@cindex history expansion
+History expansion assigns special meaning to the character @kbd{!}.
+@iftex
+@xref{Event Designators}.
+@end iftex
+Since @kbd{!} is also the logical not operator in C, history expansion
+is off by default. If you decide to enable history expansion with the
+@code{set history expansion on} command, you may sometimes need to
+follow @kbd{!} (when it is used as logical not, in an expression) with
+a space or a tab to prevent it from being expanded. The readline
+history facilities will not attempt substitution on the strings
+@kbd{!=} and @kbd{!(}, even when history expansion is enabled.
+
+The commands to control history expansion are:
+
+@table @code
+
+@kindex set history expansion
+@item set history expansion on
+@itemx set history expansion
+Enable history expansion. History expansion is off by default.
+
+@item set history expansion off
+Disable history expansion.
+
+The readline code comes with more complete documentation of
+editing and history expansion features. Users unfamiliar with @code{emacs}
+or @code{vi} may wish to read it.
+@iftex
+@xref{Command Line Editing}.
+@end iftex
+
+@c @group
+@kindex show history
+@item show history
+@itemx show history filename
+@itemx show history save
+@itemx show history size
+@itemx show history expansion
+These commands display the state of the _GDBN__ history parameters.
+@code{show history} by itself displays all four states.
+@c @end group
+@end table
+
+@table @code
+@kindex show commands
+@item show commands
+Display the last ten commands in the command history.
+
+@item show commands @var{n}
+Print ten commands centered on command number @var{n}.
+
+@item show commands +
+Print ten commands just after the commands last printed.
+@end table
+
+@node Screen Size, Numbers, History, Controlling _GDBN__
+@section Screen Size
+@cindex size of screen
+@cindex pauses in output
+
+Certain commands to _GDBN__ may produce large amounts of information
+output to the screen. To help you read all of it, _GDBN__ pauses and
+asks you for input at the end of each page of output. Type @key{RET}
+when you want to continue the output. _GDBN__ also uses the screen
+width setting to determine when to wrap lines of output. Depending on
+what is being printed, it tries to break the line at a readable place,
+rather than simply letting it overflow onto the following line.
+
+Normally _GDBN__ knows the size of the screen from the termcap data base
+together with the value of the @code{TERM} environment variable and the
+@code{stty rows} and @code{stty cols} settings. If this is not correct,
+you can override it with the @code{set height} and @code{set
+width} commands:
+
+@table @code
+@item set height @var{lpp}
+@itemx show height
+@itemx set width @var{cpl}
+@itemx show width
+@kindex set height
+@kindex set width
+@kindex show width
+@kindex show height
+These @code{set} commands specify a screen height of @var{lpp} lines and
+a screen width of @var{cpl} characters. The associated @code{show}
+commands display the current settings.
+
+If you specify a height of zero lines, _GDBN__ will not pause during output
+no matter how long the output is. This is useful if output is to a file
+or to an editor buffer.
+@end table
+
+@node Numbers, Messages/Warnings, Screen Size, Controlling _GDBN__
+@section Numbers
+@cindex number representation
+@cindex entering numbers
+
+You can always enter numbers in octal, decimal, or hexadecimal in _GDBN__ by
+the usual conventions: octal numbers begin with @samp{0}, decimal
+numbers end with @samp{.}, and hexadecimal numbers begin with @samp{0x}.
+Numbers that begin with none of these are, by default, entered in base
+10; likewise, the default display for numbers---when no particular
+format is specified---is base 10. You can change the default base for
+both input and output with the @code{set radix} command.
+
+@table @code
+@kindex set radix
+@item set radix @var{base}
+Set the default base for numeric input and display. Supported choices
+for @var{base} are decimal 2, 8, 10, 16. @var{base} must itself be
+specified either unambiguously or using the current default radix; for
+example, any of
@example
-set $pc = 0x485
+set radix 1010
+set radix 012
+set radix 10.
+set radix 0xa
@end example
-@noindent
-causes the next @samp{cont} command or stepping command to execute at
-address 0x485, rather than at the address where the program stopped.
-@xref{Stepping}.
+@noindent
+will set the base to decimal. On the other hand, @samp{set radix 10}
+will leave the radix unchanged no matter what it was.
+
+@kindex show radix
+@item show radix
+Display the current default base for numeric input and display.
+@end table
+
+@node Messages/Warnings, , Numbers, Controlling _GDBN__
+@section Optional Warnings and Messages
+
+By default, _GDBN__ is silent about its inner workings. If you are running
+on a slow machine, you may want to use the @code{set verbose} command.
+It will make _GDBN__ tell you when it does a lengthy internal operation, so
+you will not think it has crashed.
+
+Currently, the messages controlled by @code{set verbose} are those
+which announce that the symbol table for a source file is being read
+(@pxref{Files, ,Commands to Specify Files}, in the description of the
+command @code{symbol-file}).
+@c The following is the right way to do it, but emacs 18.55 does not support
+@c @ref, and neither the emacs lisp manual version of texinfmt or makeinfo
+@c is released.
+@ignore
+see @code{symbol-file} in @ref{Files, ,Commands to Specify Files}).
+@end ignore
+
+@table @code
+@kindex set verbose
+@item set verbose on
+Enables _GDBN__'s output of certain informational messages.
+
+@item set verbose off
+Disables _GDBN__'s output of certain informational messages.
-The most common occasion to use the @samp{jump} command is to back up,
-perhaps with more breakpoints set, over a portion of a program that has
-already executed.
+@kindex show verbose
+@item show verbose
+Displays whether @code{set verbose} is on or off.
+@end table
-@node Signaling, Returning, Jumping, Altering
-@section Giving the Program a Signal
+By default, if _GDBN__ encounters bugs in the symbol table of an object
+file, it is silent; but if you are debugging a compiler, you may find
+this information useful (@pxref{Symbol Errors, ,Errors Reading Symbol Files}).
@table @code
-@item signal @var{signalnum}
-@kindex signal
-Resume execution where the program stopped, but give it immediately the
-signal number @var{signalnum}.
+@kindex set complaints
+@item set complaints @var{limit}
+Permits _GDBN__ to output @var{limit} complaints about each type of unusual
+symbols before becoming silent about the problem. Set @var{limit} to
+zero to suppress all complaints; set it to a large number to prevent
+complaints from being suppressed.
-Alternatively, if @var{signalnum} is zero, continue execution without
-giving a signal. This is useful when the program stopped on account of
-a signal and would ordinary see the signal when resumed with the
-@samp{cont} command; @samp{signal 0} causes it to resume without a
-signal.
+@kindex show complaints
+@item show complaints
+Displays how many symbol complaints _GDBN__ is permitted to produce.
@end table
-@node Returning, Calling, Signaling, Altering
-@section Returning from a Function
+By default, _GDBN__ is cautious, and asks what sometimes seem to be a
+lot of stupid questions to confirm certain commands. For example, if
+you try to run a program which is already running:
-@table @code
-@item return
-@cindex returning from a function
-@kindex return
-You can cancel execution of a function call with the @samp{return}
-command.
-@end table
+@example
+(_GDBP__) run
+The program being debugged has been started already.
+Start it from the beginning? (y or n)
+@end example
-This command has the effect of discarding the selected stack
-frame (and all frames within it), so that control moves to the caller of
-that function. You can think of this as making the discarded frame
-return prematurely.
+If you are willing to unflinchingly face the consequences of your own
+commands, you can disable this ``feature'':
-First select the stack frame that you wish to return from
-(@pxref{Selection}). Then type the @samp{return} command. If you wish
-to specify the value to be returned, give that as an argument.
+@table @code
+@kindex set confirm
+@cindex flinching
+@cindex confirmation
+@cindex stupid questions
+@item set confirm off
+Disables confirmation requests.
-This pops the selected stack frame (and any other frames inside of it),
-leaving its caller as the innermost remaining frame. That frame becomes
-selected. The specified value is stored in the registers used for
-returning values of functions.
+@item set confirm on
+Enables confirmation requests (the default).
-The @samp{return} command does not resume execution; it leaves the
-program stopped in the state that would exist if the function had just
-returned. Contrast this with the @samp{finish} command
-(@pxref{Stepping}), which resumes execution until the selected stack
-frame returns @emph{naturally}.
+@item show confirm
+@kindex show confirm
+Displays state of confirmation requests.
+@end table
-@node Calling, , Returning, Altering
-@comment node-name, next, previous, up
-@section Calling your Program's Functions
+@c FIXME this does not really belong here. But where *does* it belong?
+@cindex reloading symbols
+Some systems allow individual object files that make up your program to
+be replaced without stopping and restarting your program.
+_if__(_VXWORKS__)
+For example, in VxWorks you can simply recompile a defective object file
+and keep on running.
+_fi__(_VXWORKS__)
+If you are running on one of these systems, you can allow _GDBN__ to
+reload the symbols for automatically relinked modules:
-@cindex calling functions
-@kindex call
@table @code
-@item call @var{expr}
-Evaluate the expression @var{expr} without displaying @code{void}
-returned values.
+@kindex set symbol-reloading
+@item set symbol-reloading on
+Replace symbol definitions for the corresponding source file when an
+object file with a particular name is seen again.
+
+@item set symbol-reloading off
+Do not replace symbol definitions when re-encountering object files of
+the same name. This is the default state; if you are not running on a
+system that permits automatically relinking modules, you should leave
+@code{symbol-reloading} off, since otherwise _GDBN__ may discard symbols
+when linking large programs, that may contain several modules (from
+different directories or libraries) with the same name.
+
+@item show symbol-reloading
+Show the current @code{on} or @code{off} setting.
@end table
-You can use this variant of the @samp{print} command if you want to
-execute some piece of your program, but without cluttering the output
-with @code{void} returned values. The result is printed and saved in
-the value history, if it is not void.
-
-@node Sequences, Emacs, Altering, Top
+@node Sequences, Emacs, Controlling _GDBN__, Top
@chapter Canned Sequences of Commands
-Aside from breakpoint commands (@pxref{Break Commands}),_GDBN__ provides two
-ways to store sequences of commands for execution as a unit:
-user-defined commands and command files.
+Aside from breakpoint commands (@pxref{Break Commands, ,Breakpoint
+Command Lists}), _GDBN__ provides two ways to store sequences of commands
+for execution as a unit: user-defined commands and command files.
@menu
-* Define:: User-defined commands.
-* Command Files:: Command files.
-* Output:: Controlled output commands useful in
- user-defined commands and command files.
+* Define:: User-Defined Commands
+* Command Files:: Command Files
+* Output:: Commands for Controlled Output
@end menu
@node Define, Command Files, Sequences, Sequences
@cindex user-defined command
A @dfn{user-defined command} is a sequence of _GDBN__ commands to which you
-assign a new name as a command. This is done with the @samp{define}
+assign a new name as a command. This is done with the @code{define}
command.
@table @code
by that name, you are asked to confirm that you want to redefine it.
The definition of the command is made up of other _GDBN__ command lines,
-which are given following the @samp{define} command. The end of these
-commands is marked by a line containing @samp{end}.
+which are given following the @code{define} command. The end of these
+commands is marked by a line containing @code{end}.
@item document @var{commandname}
@kindex document
Give documentation to the user-defined command @var{commandname}. The
command @var{commandname} must already be defined. This command reads
-lines of documentation just as @samp{define} reads the lines of the
-command definition, ending with @samp{end}. After the @samp{document}
-command is finished, @samp{help} on command @var{commandname} will print
+lines of documentation just as @code{define} reads the lines of the
+command definition, ending with @code{end}. After the @code{document}
+command is finished, @code{help} on command @var{commandname} will print
the documentation you have specified.
-You may use the @samp{document} command again to change the
-documentation of a command. Redefining the command with @samp{define}
+You may use the @code{document} command again to change the
+documentation of a command. Redefining the command with @code{define}
does not change the documentation.
+
+@item help user-defined
+@kindex help user-defined
+List all user-defined commands, with the first line of the documentation
+(if any) for each.
+
+@item show user
+@itemx show user @var{commandname}
+@kindex show user
+Display the _GDBN__ commands used to define @var{commandname} (but not its
+documentation). If no @var{commandname} is given, display the
+definitions for all user-defined commands.
@end table
User-defined commands do not take arguments. When they are executed, the
Commands that would ask for confirmation if used interactively proceed
without asking when used inside a user-defined command. Many _GDBN__ commands
that normally print messages to say what they are doing omit the messages
-when used in user-defined command.
+when used in a user-defined command.
@node Command Files, Output, Define, Sequences
@section Command Files
@cindex command files
A command file for _GDBN__ is a file of lines that are _GDBN__ commands. Comments
-(lines starting with @samp{#}) may also be included. An empty line in a
+(lines starting with @kbd{#}) may also be included. An empty line in a
command file does nothing; it does not mean to repeat the last command, as
it would from the terminal.
@cindex init file
-@cindex @file{._GDBP__init}
-When you start _GDBN__, it first executes commands from its @dfn{init files}.
-These are files named @file{._GDBP__init}. _GDBN__ reads the init file (if any)
-in your home directory and then the init file (if any) in the current
-working directory. (The init files are not executed if the @samp{-nx}
-option is given.) You can also request the execution of a command file
-with the @samp{source} command:
+@cindex @file{_GDBINIT__}
+When you start _GDBN__, it automatically executes commands from its
+@dfn{init files}. These are files named @file{_GDBINIT__}. _GDBN__ reads
+the init file (if any) in your home directory and then the init file
+(if any) in the current working directory. (The init files are not
+executed if you use the @samp{-nx} option; @pxref{Mode Options,
+,Choosing Modes}.) You can also request the execution of a command
+file with the @code{source} command:
@table @code
@item source @var{filename}
Commands that would ask for confirmation if used interactively proceed
without asking when used in a command file. Many _GDBN__ commands that
normally print messages to say what they are doing omit the messages
-when used in a command file.
+when called from command files.
@node Output, , Command Files, Sequences
@section Commands for Controlled Output
-During the execution of a command file or a user-defined command, the only
-output that appears is what is explicitly printed by the commands of the
-definition. This section describes three commands useful for generating
-exactly the output you want.
+During the execution of a command file or a user-defined command, normal
+_GDBN__ output is suppressed; the only output that appears is what is
+explicitly printed by the commands in the definition. This section
+describes three commands useful for generating exactly the output you
+want.
@table @code
@item echo @var{text}
@kindex echo
-@comment I don't consider backslash-space a standard C escape sequence
-@comment because it's not in ANSI.
-Print @var{text}. Nonprinting characters can be included in @var{text}
-using C escape sequences, such as @samp{\n} to print a newline. @b{No
-newline will be printed unless you specify one.} In addition to the
-standard C escape sequences a backslash followed by a space stands for a
-space. This is useful for outputting a string with spaces at the
-beginning or the end, since leading and trailing spaces are otherwise
-trimmed from all arguments. Thus, to print @samp{@ and foo =@ }, use the
-command @samp{echo \@ and foo = \@ }.
-@comment FIXME: verify hard copy actually issues enspaces for '@ '! Will this
-@comment confuse texinfo?
+@c I do not consider backslash-space a standard C escape sequence
+@c because it is not in ANSI.
+Print @var{text}. Nonprinting characters can be included in
+@var{text} using C escape sequences, such as @samp{\n} to print a
+newline. @strong{No newline will be printed unless you specify one.}
+In addition to the standard C escape sequences, a backslash followed
+by a space stands for a space. This is useful for outputting a
+string with spaces at the beginning or the end, since leading and
+trailing spaces are otherwise trimmed from all arguments.
+To print @samp{@w{ }and foo =@w{ }}, use the command
+@samp{echo \@w{ }and foo = \@w{ }}.
A backslash at the end of @var{text} can be used, as in C, to continue
the command onto subsequent lines. For example,
@kindex output
Print the value of @var{expression} and nothing but that value: no
newlines, no @samp{$@var{nn} = }. The value is not entered in the
-value history either. @xref{Expressions} for more information on
-expressions.
+value history either. @xref{Expressions, ,Expressions}, for more information on
+expressions.
@item output/@var{fmt} @var{expression}
-Print the value of @var{expression} in format @var{fmt}.
-@xref{Output formats}, for more information.
+Print the value of @var{expression} in format @var{fmt}. You can use
+the same formats as for @code{print}; @pxref{Output formats}, for more
+information.
@item printf @var{string}, @var{expressions}@dots{}
@kindex printf
Print the values of the @var{expressions} under the control of
@var{string}. The @var{expressions} are separated by commas and may
be either numbers or pointers. Their values are printed as specified
-by @var{string}, exactly as if the program were to execute
+by @var{string}, exactly as if your program were to execute
@example
printf (@var{string}, @var{expressions}@dots{});
For example, you can print two values in hex like this:
-@example
+@smallexample
printf "foo, bar-foo = 0x%x, 0x%x\n", foo, bar-foo
-@end example
+@end smallexample
The only backslash-escape sequences that you can use in the format
string are the simple ones that consist of backslash followed by a
letter.
@end table
-@node Emacs, Remote, Sequences, Top
+_if__(_LUCID__)
+@node Emacs, Energize, Sequences, Top
+_fi__(_LUCID__)
+_if__(!_LUCID__)
+@node Emacs, _GDBN__ Bugs, Sequences, Top
+_fi__(!_LUCID__)
@chapter Using _GDBN__ under GNU Emacs
@cindex emacs
@itemize @bullet
@item
-All ``terminal'' input and output goes through the Emacs buffer. This
-applies both to _GDBN__ commands and their output, and to the input and
-output done by the program you are debugging.
+All ``terminal'' input and output goes through the Emacs buffer.
+@end itemize
+
+This applies both to _GDBN__ commands and their output, and to the input
+and output done by the program you are debugging.
This is useful because it means that you can copy the text of previous
commands and input them again; you can even use parts of the output
in this way.
-All the facilities of Emacs' Shell mode are available for this purpose.
+All the facilities of Emacs' Shell mode are available for interacting
+with your program. In particular, you can send signals the usual
+way---for example, @kbd{C-c C-c} for an interrupt, @kbd{C-c C-z} for a
+stop.
+@itemize @bullet
@item
-_GDBN__ displays source code through Emacs. Each time _GDBN__ displays a
-stack frame, Emacs automatically finds the source file for that frame
-and puts an arrow (@samp{=>}) at the left margin of the current line.
-Emacs uses a separate buffer for source display, and splits the window
-to show both your _GDBN__ session and the source.
+_GDBN__ displays source code through Emacs.
+@end itemize
+
+Each time _GDBN__ displays a stack frame, Emacs automatically finds the
+source file for that frame and puts an arrow (_0__@samp{=>}_1__) at the
+left margin of the current line. Emacs uses a separate buffer for
+source display, and splits the window to show both your _GDBN__ session
+and the source.
-Explicit _GDBN__ @samp{list} or search commands still produce output as
+Explicit _GDBN__ @code{list} or search commands still produce output as
usual, but you probably will have no reason to use them.
-@end itemize
@quotation
@emph{Warning:} If the directory where your program resides is not your
current directory, it can be easy to confuse Emacs about the location of
the source files, in which case the auxiliary display buffer will not
appear to show your source. _GDBN__ can find programs by searching your
-environment's @samp{PATH} variable, so the _GDBN__ I/O session will proceed
-normally; but Emacs doesn't get enough information back from _GDBN__ to
-locate the source files in this situation. To avoid this problem,
-either start _GDBN__ mode from the directory where your program resides, or
-specify a full path name when prompted for the @kbd{M-x gdb} argument.
-
-A similar confusion can result if you use the _GDBN__ @samp{file} command to
+environment's @code{PATH} variable, so the _GDBN__ input and output
+session will proceed normally; but Emacs does not get enough information
+back from _GDBN__ to locate the source files in this situation. To
+avoid this problem, either start _GDBN__ mode from the directory where
+your program resides, or specify a full path name when prompted for the
+@kbd{M-x gdb} argument.
+
+A similar confusion can result if you use the _GDBN__ @code{file} command to
switch to debugging a program in some other location, from an existing
-_GDBN__ I/O buffer in Emacs.
+_GDBN__ buffer in Emacs.
@end quotation
-By default, @kbd{M-x gdb} calls the program called ``@code{gdb}''. If
+By default, @kbd{M-x gdb} calls the program called @file{gdb}. If
you need to call _GDBN__ by a different name (for example, if you keep
several configurations around, with different names) you can set the
Emacs variable @code{gdb-command-name}; for example,
+
@example
(setq gdb-command-name "mygdb")
@end example
+
@noindent
(preceded by @kbd{ESC ESC}, or typed in the @code{*scratch*} buffer, or
-in your @samp{.emacs} file) will make Emacs call the program named
+in your @file{.emacs} file) will make Emacs call the program named
``@code{mygdb}'' instead.
In the _GDBN__ I/O buffer, you can use these special Emacs commands in
Describe the features of Emacs' _GDBN__ Mode.
@item M-s
-Execute to another source line, like the _GDBN__ @samp{step} command; also
+Execute to another source line, like the _GDBN__ @code{step} command; also
update the display window to show the current file and location.
@item M-n
Execute to next source line in this function, skipping all function
-calls, like the _GDBN__ @samp{next} command. Then update the display window
+calls, like the _GDBN__ @code{next} command. Then update the display window
to show the current file and location.
@item M-i
-Execute one instruction, like the _GDBN__ @samp{stepi} command; update
+Execute one instruction, like the _GDBN__ @code{stepi} command; update
display window accordingly.
@item M-x gdb-nexti
-Execute to next instruction, using the _GDBN__ @samp{nexti} command; update
+Execute to next instruction, using the _GDBN__ @code{nexti} command; update
display window accordingly.
@item C-c C-f
Execute until exit from the selected stack frame, like the _GDBN__
-@samp{finish} command.
+@code{finish} command.
@item M-c
-@comment C-c C-p in emacs 19
-Continue execution of the program, like the _GDBN__ @samp{cont} command.
+Continue execution of your program, like the _GDBN__ @code{continue}
+command.
+
+@emph{Warning:} In Emacs v19, this command is @kbd{C-c C-p}.
@item M-u
-@comment C-c C-u in emacs 19
Go up the number of frames indicated by the numeric argument
(@pxref{Arguments, , Numeric Arguments, emacs, The GNU Emacs Manual}),
-like the _GDBN__ @samp{up} command.@refill
+like the _GDBN__ @code{up} command.
+
+@emph{Warning:} In Emacs v19, this command is @kbd{C-c C-u}.
@item M-d
-@comment C-c C-d in emacs 19
Go down the number of frames indicated by the numeric argument, like the
-_GDBN__ @samp{down} command.
+_GDBN__ @code{down} command.
+
+@emph{Warning:} In Emacs v19, this command is @kbd{C-c C-d}.
@item C-x &
Read the number where the cursor is positioned, and insert it at the end
of the _GDBN__ I/O buffer. For example, if you wish to disassemble code
around an address that was displayed earlier, type @kbd{disassemble};
then move the cursor to the address display, and pick up the
-argument for @samp{disassemble} by typing @kbd{C-x &}.
+argument for @code{disassemble} by typing @kbd{C-x &}.
You can customize this further on the fly by defining elements of the list
-@samp{gdb-print-command}; once it is defined, you can format or
+@code{gdb-print-command}; once it is defined, you can format or
otherwise process numbers picked up by @kbd{C-x &} before they are
-inserted. A numeric argument to @kbd{C-x &} will both flag that you
+inserted. A numeric argument to @kbd{C-x &} will both indicate that you
wish special formatting, and act as an index to pick an element of the
list. If the list element is a string, the number to be inserted is
-formatted using the Emacs function @samp{format}; otherwise the number
+formatted using the Emacs function @code{format}; otherwise the number
is passed as an argument to the corresponding list element.
-
-@item M-x gdb-display-frame
-Explicitly request display of the source code surrounding the current
-frame location, in another window. _GDBN__ does this display automatically;
-but if, for example, you accidentally kill the buffer where it is
-displayed, this command is a way of getting it back.
@end table
In any source file, the Emacs command @kbd{C-x SPC} (@code{gdb-break})
tells _GDBN__ to set a breakpoint on the source line point is on.
+If you accidentally delete the source-display buffer, an easy way to get
+it back is to type the command @code{f} in the _GDBN__ buffer, to
+request a frame display; when you run under Emacs, this will recreate
+the source buffer if necessary to show you the context of the current
+frame.
+
The source files displayed in Emacs are in ordinary Emacs buffers
which are visiting the source files in the usual way. You can edit
the files with these buffers if you wish; but keep in mind that _GDBN__
delete lines from the text, the line numbers that _GDBN__ knows will cease
to correspond properly to the code.
-@comment The following dropped because Epoch is nonstandard. Reactivate
+@c The following dropped because Epoch is nonstandard. Reactivate
@ignore
-@kindex emacs epoch environment
+@kindex emacs epoch environment
@kindex epoch
@kindex inspect
-Version 18 of Emacs has a built-in window system called the @samp{epoch}
+Version 18 of Emacs has a built-in window system called the @code{epoch}
environment. Users of this environment can use a new command,
-@samp{inspect} which performs identically to @samp{print} except that
+@code{inspect} which performs identically to @code{print} except that
each value is printed in its own window.
@end ignore
-@node Remote, _GDBN__ Bugs, Emacs, Top
-@chapter Remote Debugging
-@cindex remote debugging
-
-If you are trying to debug a program running on a machine that can't run
-_GDBN__ in the usual way, it is often useful to use remote debugging. For
-example, you might be debugging an operating system kernel, or debugging
-a small system which does not have a general purpose operating system
-powerful enough to run a full-featured debugger. Currently _GDBN__ supports
-remote debugging over a serial connection, and (using Sun RPC) over a
-TCP/IP connection.
-
-The program to be debugged on the remote machine needs to contain a
-debugging device driver which talks to _GDBN__ over the serial line. The
-same version of _GDBN__ that is used ordinarily can be used for this.
-Several sample remote debugging drivers are distributed with _GDBN__; see
-the @file{README} file in the _GDBN__ distribution for more information.
-
-@menu
-* Remote Commands:: Commands used to start and finish remote debugging.
-@end menu
-
-For details of the communication protocol, see the comments in the _GDBN__
-source file @file{remote.c}.
-
-@node Remote Commands, , Remote, Remote
-@section Commands for Remote Debugging
-
-To start remote debugging, first run _GDBN__ and specify as an executable file
-the program that is running in the remote machine. This tells _GDBN__ how
-to find the program's symbols and the contents of its pure text. Then
-establish communication using the @samp{target remote} command with a device
-name as an argument. For example:
-
-@example
-target remote /dev/ttyb
-@end example
-
-@noindent
-if the serial line is connected to the device named @file{/dev/ttyb}. This
-will stop the remote machine if it is not already stopped.
-
-Now you can use all the usual commands to examine and change data and to
-step and continue the remote program.
-
-To resume the remote program and stop debugging it, use the @samp{detach}
-command.
-
-Other remote targets be available in your
-configuration of _GDBN__; use @samp{info targets} to list them.
-
-@table @code
-@item reset
-@kindex reset
-For a target attached through a serial line, this command sends a
-``break'' to the remote target system; this is only useful if the target
-has been equipped with a circuit to perform a hard reset (or some other
-interesting action) when a break is detected.
-@end table
-
-@node _GDBN__ Bugs, Installing _GDBN__, Remote, Top
-@comment node-name, next, previous, up
+_if__(_LUCID__)
+@node Energize, _GDBN__ Bugs, Emacs, Top
+@chapter Using _GDBN__ with Energize
+
+@cindex Energize
+The Energize Programming System is an integrated development environment
+that includes a point-and-click interface to many programming tools.
+When you use _GDBN__ in this environment, you can use the standard
+Energize graphical interface to drive _GDBN__; you can also, if you
+choose, type _GDBN__ commands as usual in a debugging window. Even if
+you use the graphical interface, the debugging window (which uses Emacs,
+and resembles the standard Emacs interface to _GDBN__) displays the
+equivalent commands, so that the history of your debugging session is
+properly reflected.
+
+When Energize starts up a _GDBN__ session, it uses one of the
+command-line options @samp{-energize} or @samp{-cadillac} (``cadillac''
+is the name of the communications protocol used by the Energize system).
+This option makes _GDBN__ run as one of the tools in the Energize Tool
+Set: it sends all output to the Energize kernel, and accept input from
+it as well.
+
+See the user manual for the Energize Programming System for
+information on how to use the Energize graphical interface and the other
+development tools that Energize integrates with _GDBN__.
+
+@node _GDBN__ Bugs, Renamed Commands, Energize, Top
+_fi__(_LUCID__)
+_if__(!_LUCID__)
+@node _GDBN__ Bugs, Renamed Commands, Emacs, Top
+_fi__(!_LUCID__)
@chapter Reporting Bugs in _GDBN__
@cindex Bugs in _GDBN__
@cindex Reporting Bugs in _GDBN__
Your bug reports play an essential role in making _GDBN__ reliable.
Reporting a bug may help you by bringing a solution to your problem, or it
-may not. But in any case the important function of a bug report is to help
+may not. But in any case the principal function of a bug report is to help
the entire community by making the next version of _GDBN__ work better. Bug
reports are your contribution to the maintenance of _GDBN__.
In order for a bug report to serve its purpose, you must include the
-information that makes for fixing the bug.
+information that enables us to fix the bug.
@menu
-* Bug Criteria:: Have You Found a Bug?
-* Bug Reporting:: How to Report Bugs
+* Bug Criteria:: Have You Found a Bug?
+* Bug Reporting:: How to Report Bugs
@end menu
@node Bug Criteria, Bug Reporting, _GDBN__ Bugs, _GDBN__ Bugs
@node Bug Reporting, , Bug Criteria, _GDBN__ Bugs
@section How to Report Bugs
@cindex Bug Reports
-@cindex Compiler Bugs, Reporting
+@cindex _GDBN__ Bugs, Reporting
-@comment The following is meant to be neutral and helpful, not just a plug for
-@comment is welcome.
A number of companies and individuals offer support for GNU products.
If you obtained _GDBN__ from a support organization, we recommend you
-contact that organization first.
+contact that organization first.
-Among these organizations are Cygnus Support (Palo Alto CA, USA); C2V
-(Paris, France); Dynamix Corporation (King of Prussia PA, USA); The Nice
-Computer Company (Perth, Australia); Optimal Solutions (Seattle WA,
-USA); and The Pharos Group (Las Cruces NM, USA).
-
-Full contact information is in the file @samp{etc/SERVICE} in the GNU
-Emacs distribution. Numerous individual consultants are also listed
-there.
-@comment END NEUTRAL+HELPFUL section
+Contact information for many support companies and individuals is
+available in the file @file{etc/SERVICE} in the GNU Emacs distribution.
In any event, we also recommend that you send bug reports for _GDBN__ to one
of these addresses:
@strong{Do not send bug reports to @samp{info-gdb}, or to
@samp{help-gdb}, or to any newsgroups.} Most users of _GDBN__ do not want to
-receive bug reports. Those that do, have asked to be on @samp{bug-gdb}.
+receive bug reports. Those that do, have arranged to receive @samp{bug-gdb}.
-The mailing list @samp{bug-gdb} has a newsgroup which serves as a
-repeater. The mailing list and the newsgroup carry exactly the same
-messages. Often people think of posting bug reports to the newsgroup
-instead of mailing them. This appears to work, but it has one problem
-which can be crucial: a newsgroup posting does not contain a mail path
-back to the sender. Thus, if we need to ask for more information, we
-may be unable to reach you. For this reason, it is better to send bug
-reports to the mailing list.
+The mailing list @samp{bug-gdb} has a newsgroup @samp{gnu.gdb.bug} which
+serves as a repeater. The mailing list and the newsgroup carry exactly
+the same messages. Often people think of posting bug reports to the
+newsgroup instead of mailing them. This appears to work, but it has one
+problem which can be crucial: a newsgroup posting often lacks a mail
+path back to the sender. Thus, if we need to ask for more information,
+we may be unable to reach you. For this reason, it is better to send
+bug reports to the mailing list.
As a last resort, send bug reports on paper to:
@example
GNU Debugger Bugs
+Free Software Foundation
545 Tech Square
Cambridge, MA 02139
@end example
fact or leave it out, state it!
Often people omit facts because they think they know what causes the
-problem and they conclude that some details don't matter. Thus, you might
+problem and assume that some details do not matter. Thus, you might
assume that the name of the variable you use in an example does not matter.
-Well, probably it doesn't, but one cannot be sure. Perhaps the bug is a
+Well, probably it does not, but one cannot be sure. Perhaps the bug is a
stray memory reference which happens to fetch from the location where that
name is stored in memory; perhaps, if the name were different, the contents
of that location would fool the debugger into doing the right thing despite
easiest thing for you to do, and the most helpful.
Keep in mind that the purpose of a bug report is to enable us to fix
-the bug if it is not known. It isn't very important what happens if
+the bug if it is new to us. It is not as important as what happens if
the bug is already known. Therefore, always write your bug reports on
-the assumption that the bug is not known.
+the assumption that the bug has not been reported previously.
Sometimes people give a few sketchy facts and ask, ``Does this ring a
bell?'' Those bug reports are useless, and we urge everyone to
@itemize @bullet
@item
-The version of _GDBN__. _GDBN__ announces it on startup; you can also print it
-at any time using @samp{info version}.
+The version of _GDBN__. _GDBN__ announces it if you start with no
+arguments; you can also print it at any time using @code{show version}.
-Without this, we won't know whether there is any point in looking for
+Without this, we will not know whether there is any point in looking for
the bug in the current version of _GDBN__.
@item
-A complete input script, and all necessary source files, that will
-reproduce the bug.
+The type of machine you are using, and the operating system name and
+version number.
@item
What compiler (and its version) was used to compile _GDBN__---e.g.
-``_GCC__-1.37.1''.
+``_GCC__-2.0''.
@item
-What compiler (and its version) was used to compile _GDBN__.
+What compiler (and its version) was used to compile the program you
+are debugging---e.g. ``_GCC__-2.0''.
@item
-The command arguments you gave the compiler to compile that example and
+The command arguments you gave the compiler to compile your example and
observe the bug. For example, did you use @samp{-O}? To guarantee
-you won't omit something important, list them all.
+you will not omit something important, list them all. A copy of the
+Makefile (or the output from make) is sufficient.
If we were to try to guess the arguments, we would probably guess wrong
-and then we would not encounter the bug.
+and then we might not encounter the bug.
@item
-The type of machine you are using, and the operating system name and
-version number.
+A complete input script, and all necessary source files, that will
+reproduce the bug.
@item
A description of what behavior you observe that you believe is
incorrect. For example, ``It gets a fatal signal.''
-Of course, if the bug is that _GDBN__ gets a fatal signal, then we
-will certainly notice it. But if the bug is incorrect output, we might
-not notice unless it is glaringly wrong.
+Of course, if the bug is that _GDBN__ gets a fatal signal, then we will
+certainly notice it. But if the bug is incorrect output, we might not
+notice unless it is glaringly wrong. We are human, after all. You
+might as well not give us a chance to make a mistake.
Even if the problem you experience is a fatal signal, you should still
say so explicitly. Suppose something strange is going on, such as,
your copy of _GDBN__ is out of synch, or you have encountered a
bug in the C library on your system. (This has happened!) Your copy
-might crash and ours would not. If you @i{told} us to expect a crash,
+might crash and ours would not. If you told us to expect a crash,
then when ours fails to crash, we would know that the bug was not
happening for us. If you had not told us to expect a crash, then we
would not be able to draw any conclusion from our observations.
diffs. If you even discuss something in the _GDBN__ source, refer to
it by context, not by line number.
-The line numbers in our development sources don't match those in your
+The line numbers in our development sources will not match those in your
sources. Your line numbers would convey no useful information to us.
-
@end itemize
Here are some things that are not necessary:
Of course, if you can find a simpler example to report @emph{instead}
of the original one, that is a convenience for us. Errors in the
output will be easier to spot, running under the debugger will take
-less time, etc.
+less time, etc.
-However, simplification is not vital; if you don't want to do this,
+However, simplification is not vital; if you do not want to do this,
report the bug anyway and send us the entire test case you used.
@item
A patch for the bug.
-A patch for the bug does help us if it is a good one. But don't omit
+A patch for the bug does help us if it is a good one. But do not omit
the necessary information, such as the test case, on the assumption that
a patch is all we need. We might see problems with your patch and decide
to fix the problem another way, or we might not understand it at all.
Sometimes with a program as complicated as _GDBN__ it is very hard to
construct an example that will make the program follow a certain path
-through the code. If you don't send us the example, we won't be able
-to construct one, so we won't be able to verify that the bug is fixed.
+through the code. If you do not send us the example, we will not be able
+to construct one, so we will not be able to verify that the bug is fixed.
-And if we can't understand what bug you are trying to fix, or why your
-patch should be an improvement, we won't install it. A test case will
+And if we cannot understand what bug you are trying to fix, or why your
+patch should be an improvement, we will not install it. A test case will
help us to understand.
@item
A guess about what the bug is or what it depends on.
-Such guesses are usually wrong. Even we can't guess right about such
+Such guesses are usually wrong. Even we cannot guess right about such
things without first using the debugger to find the facts.
@end itemize
+@c Note: no need to update nodes for rdl-apps.texi since it appears
+@c *only* in the TeX version of the manual.
+@c Note: eventually, make a cross reference to the readline Info nodes.
@iftex
-@include readline/inc-readline.texinfo
-@include readline/inc-history.texinfo
+@c appendices describing GNU readline. Distributed with readline code.
+@include rluser.texinfo
+@include inc-hist.texi
@end iftex
-@node Installing _GDBN__, License, _GDBN__ Bugs, Top
-@appendix Installing _GDBN__
-@cindex configuring _GDBN__
+@node Renamed Commands, Formatting Documentation, _GDBN__ Bugs, Top
+@appendix Renamed Commands
+
+The following commands were renamed in GDB 4, in order to make the
+command set as a whole more consistent and easier to use and remember:
+
+@kindex add-syms
+@kindex delete environment
+@kindex info copying
+@kindex info convenience
+@kindex info directories
+@kindex info editing
+@kindex info history
+@kindex info targets
+@kindex info values
+@kindex info version
+@kindex info warranty
+@kindex set addressprint
+@kindex set arrayprint
+@kindex set prettyprint
+@kindex set screen-height
+@kindex set screen-width
+@kindex set unionprint
+@kindex set vtblprint
+@kindex set demangle
+@kindex set asm-demangle
+@kindex set sevenbit-strings
+@kindex set array-max
+@kindex set caution
+@kindex set history write
+@kindex show addressprint
+@kindex show arrayprint
+@kindex show prettyprint
+@kindex show screen-height
+@kindex show screen-width
+@kindex show unionprint
+@kindex show vtblprint
+@kindex show demangle
+@kindex show asm-demangle
+@kindex show sevenbit-strings
+@kindex show array-max
+@kindex show caution
+@kindex show history write
+@kindex unset
+
+@c TEXI2ROFF-KILL
+@ifinfo
+@c END TEXI2ROFF-KILL
+@example
+OLD COMMAND NEW COMMAND
+@c TEXI2ROFF-KILL
+--------------- -------------------------------
+@c END TEXI2ROFF-KILL
+add-syms add-symbol-file
+delete environment unset environment
+info convenience show convenience
+info copying show copying
+info directories show directories
+info editing show commands
+info history show values
+info targets help target
+info values show values
+info version show version
+info warranty show warranty
+set/show addressprint set/show print address
+set/show array-max set/show print elements
+set/show arrayprint set/show print array
+set/show asm-demangle set/show print asm-demangle
+set/show caution set/show confirm
+set/show demangle set/show print demangle
+set/show history write set/show history save
+set/show prettyprint set/show print pretty
+set/show screen-height set/show height
+set/show screen-width set/show width
+set/show sevenbit-strings set/show print sevenbit-strings
+set/show unionprint set/show print union
+set/show vtblprint set/show print vtbl
+
+unset [No longer an alias for delete]
+@end example
+@c TEXI2ROFF-KILL
+@end ifinfo
+
+@tex
+\vskip \parskip\vskip \baselineskip
+\halign{\tt #\hfil &\qquad#&\tt #\hfil\cr
+{\bf Old Command} &&{\bf New Command}\cr
+add-syms &&add-symbol-file\cr
+delete environment &&unset environment\cr
+info convenience &&show convenience\cr
+info copying &&show copying\cr
+info directories &&show directories \cr
+info editing &&show commands\cr
+info history &&show values\cr
+info targets &&help target\cr
+info values &&show values\cr
+info version &&show version\cr
+info warranty &&show warranty\cr
+set{\rm / }show addressprint &&set{\rm / }show print address\cr
+set{\rm / }show array-max &&set{\rm / }show print elements\cr
+set{\rm / }show arrayprint &&set{\rm / }show print array\cr
+set{\rm / }show asm-demangle &&set{\rm / }show print asm-demangle\cr
+set{\rm / }show caution &&set{\rm / }show confirm\cr
+set{\rm / }show demangle &&set{\rm / }show print demangle\cr
+set{\rm / }show history write &&set{\rm / }show history save\cr
+set{\rm / }show prettyprint &&set{\rm / }show print pretty\cr
+set{\rm / }show screen-height &&set{\rm / }show height\cr
+set{\rm / }show screen-width &&set{\rm / }show width\cr
+set{\rm / }show sevenbit-strings &&set{\rm / }show print sevenbit-strings\cr
+set{\rm / }show unionprint &&set{\rm / }show print union\cr
+set{\rm / }show vtblprint &&set{\rm / }show print vtbl\cr
+\cr
+unset &&\rm(No longer an alias for delete)\cr
+}
+@end tex
+@c END TEXI2ROFF-KILL
+
+@node Formatting Documentation, Installing GDB, Renamed Commands, Top
+@appendix Formatting the Documentation
+
+@cindex GDB reference card
+@cindex reference card
+The GDB 4 release includes an already-formatted reference card, ready
+for printing on a PostScript or GhostScript printer, in the @file{gdb}
+subdirectory of the main source directory---in
+@file{gdb-_GDB_VN__/gdb/refcard.ps} of the version _GDB_VN__ release. If you have
+a PostScript or GhostScript printer, you can print the reference card
+by just sending @file{refcard.ps} to the printer.
+
+The release also includes the source for the reference card. You
+can format it, using @TeX{}, by typing:
+
+@example
+make refcard.dvi
+@end example
+
+The GDB reference card is designed to print in landscape mode on US
+``letter'' size paper; that is, on a sheet 11 inches wide by 8.5 inches
+high. You will need to specify this form of printing as an option to
+your @sc{dvi} output program.
+
+@cindex documentation
+
+All the documentation for GDB comes as part of the machine-readable
+distribution. The documentation is written in Texinfo format, which is
+a documentation system that uses a single source file to produce both
+on-line information and a printed manual. You can use one of the Info
+formatting commands to create the on-line version of the documentation
+and @TeX{} (or @code{texi2roff}) to typeset the printed version.
+
+GDB includes an already formatted copy of the on-line Info version of
+this manual in the @file{gdb} subdirectory. The main Info file is
+@file{gdb-@var{version-number}/gdb/gdb.info}, and it refers to
+subordinate files matching @samp{gdb.info*} in the same directory. If
+necessary, you can print out these files, or read them with any editor;
+but they are easier to read using the @code{info} subsystem in GNU Emacs
+or the standalone @code{info} program, available as part of the GNU
+Texinfo distribution.
+
+If you want to format these Info files yourself, you need one of the
+Info formatting programs, such as @code{texinfo-format-buffer} or
+@code{makeinfo}.
+
+If you have @code{makeinfo} installed, and are in the top level GDB
+source directory (@file{gdb-_GDB_VN__}, in the case of version _GDB_VN__), you can
+make the Info file by typing:
+
+@example
+cd gdb
+make gdb.info
+@end example
+
+If you want to typeset and print copies of this manual, you need
+@TeX{}, a printing program such as @code{lpr}, and @file{texinfo.tex},
+the Texinfo definitions file.
+
+@TeX{} is typesetting program; it does not print files directly, but
+produces output files called @sc{dvi} files. To print a typeset
+document, you need a program to print @sc{dvi} files. If your system
+has @TeX{} installed, chances are it has such a program. The precise
+command to use depends on your system; @kbd{lpr -d} is common; another
+is @kbd{dvips}. The @sc{dvi} print command may require a file name
+without any extension or a @samp{.dvi} extension.
+
+@TeX{} also requires a macro definitions file called
+@file{texinfo.tex}. This file tells @TeX{} how to typeset a document
+written in Texinfo format. On its own, @TeX{} cannot read, much less
+typeset a Texinfo file. @file{texinfo.tex} is distributed with GDB
+and is located in the @file{gdb-@var{version-number}/texinfo}
+directory.
+
+If you have @TeX{} and a @sc{dvi} printer program installed, you can
+typeset and print this manual. First switch to the the @file{gdb}
+subdirectory of the main source directory (for example, to
+@file{gdb-_GDB_VN__/gdb}) and then type:
+
+@example
+make gdb.dvi
+@end example
+
+@node Installing GDB, Copying, Formatting Documentation, Top
+@appendix Installing GDB
+@cindex configuring GDB
@cindex installation
-The script @samp{config.gdb} automates the process of preparing _GDBN__ for
-installation; you can then use @samp{make} to actually build it. For
-example,
+@iftex
+@c irrelevant in info file; it's as current as the code it lives with.
+@quotation
+@emph{Warning:} These installation instructions are current as of
+GDB version _GDB_VN__. If you're installing a more recent release
+of GDB, we may have improved the installation procedures since
+printing this manual; see the @file{README} file included in your
+release for the most recent instructions.
+@end quotation
+@end iftex
+
+GDB comes with a @code{configure} script that automates the process
+of preparing GDB for installation; you can then use @code{make} to
+build the program.
+
+The GDB distribution includes all the source code you need for GDB in
+a single directory, whose name is usually composed by appending the
+version number to @samp{gdb}.
+
+For example, the GDB version _GDB_VN__ distribution is in the @file{gdb-_GDB_VN__}
+directory. That directory contains:
+
+@table @code
+@item gdb-_GDB_VN__/configure @r{(and supporting files)}
+script for configuring GDB and all its supporting libraries.
+
+@item gdb-_GDB_VN__/gdb
+the source specific to GDB itself
+
+@item gdb-_GDB_VN__/bfd
+source for the Binary File Descriptor library
+
+@item gdb-_GDB_VN__/include
+GNU include files
+
+@item gdb-_GDB_VN__/libiberty
+source for the @samp{-liberty} free software library
+
+@item gdb-_GDB_VN__/readline
+source for the GNU command-line interface
+
+@item gdb-_GDB_VN__/glob
+source for the GNU filename pattern-matching subroutine
+
+@item gdb-_GDB_VN__/mmalloc
+source for the GNU memory-mapped malloc package
+@end table
+
+The simplest way to configure and build GDB is to run @code{configure}
+from the @file{gdb-@var{version-number}} source directory, which in
+this example is the @file{gdb-_GDB_VN__} directory.
+
+First switch to the @file{gdb-@var{version-number}} source directory
+if you are not already in it; then run @code{configure}. Pass the
+identifier for the platform on which GDB will run as an
+argument.
+
+For example:
+
+@example
+cd gdb-_GDB_VN__
+./configure @var{host}
+make
+@end example
+
+@noindent
+where @var{host} is an identifier such as @samp{sun4} or
+@samp{decstation}, that identifies the platform where GDB will run.
+
+Running @samp{configure @var{host}} followed by @code{make} builds the
+@file{bfd}, @file{readline}, @file{mmalloc}, and @file{libiberty}
+libraries, then @code{gdb} itself. The configured source files, and the
+binaries, are left in the corresponding source directories.
+
+@code{configure} is a Bourne-shell (@code{/bin/sh}) script; if your
+system does not recognize this automatically when you run a different
+shell, you may need to run @code{sh} on it explicitly:
+
+@example
+sh configure @var{host}
+@end example
+
+If you run @code{configure} from a directory that contains source
+directories for multiple libraries or programs, such as the
+@file{gdb-_GDB_VN__} source directory for version _GDB_VN__, @code{configure}
+creates configuration files for every directory level underneath (unless
+you tell it not to, with the @samp{--norecursion} option).
+
+You can run the @code{configure} script from any of the
+subordinate directories in the GDB distribution, if you only want to
+configure that subdirectory; but be sure to specify a path to it.
+
+For example, with version _GDB_VN__, type the following to configure only
+the @code{bfd} subdirectory:
+
+@example
+@group
+cd gdb-_GDB_VN__/bfd
+../configure @var{host}
+@end group
+@end example
+
+You can install @code{_GDBP__} anywhere; it has no hardwired paths.
+However, you should make sure that the shell on your path (named by
+the @samp{SHELL} environment variable) is publicly readable. Remember
+that GDB uses the shell to start your program---some systems refuse to
+let GDB debug child processes whose programs are not readable.
+
+@menu
+* Separate Objdir:: Compiling GDB in another directory
+* Config Names:: Specifying names for hosts and targets
+* configure Options:: Summary of options for configure
+@end menu
+
+@node Separate Objdir, Config Names, Installing GDB, Installing GDB
+@section Compiling GDB in Another Directory
+
+If you want to run GDB versions for several host or target machines,
+you'll need a different @code{gdb} compiled for each combination of
+host and target. @code{configure} is designed to make this easy by
+allowing you to generate each configuration in a separate subdirectory,
+rather than in the source directory. If your @code{make} program
+handles the @samp{VPATH} feature (GNU @code{make} does), running
+@code{make} in each of these directories then builds the @code{gdb}
+program specified there.
+
+To build @code{gdb} in a separate directory, run @code{configure}
+with the @samp{--srcdir} option to specify where to find the source.
+(You'll also need to specify a path to find @code{configure}
+itself from your working directory. If the path to @code{configure}
+would be the same as the argument to @samp{--srcdir}, you can leave out
+the @samp{--srcdir} option; it will be assumed.)
+
+For example, with version _GDB_VN__, you can build GDB in a separate
+directory for a Sun 4 like this:
@example
-config.gdb sun3os4
+@group
+cd gdb-_GDB_VN__
+mkdir ../gdb-sun4
+cd ../gdb-sun4
+../gdb-_GDB_VN__/configure sun4
make
+@end group
+@end example
+
+When @code{configure} builds a configuration using a remote source
+directory, it creates a tree for the binaries with the same structure
+(and using the same names) as the tree under the source directory. In
+the example, you'd find the Sun 4 library @file{libiberty.a} in the
+directory @file{gdb-sun4/libiberty}, and GDB itself in
+@file{gdb-sun4/gdb}.
+
+One popular reason to build several GDB configurations in separate
+directories is to configure GDB for cross-compiling (where GDB
+runs on one machine---the host---while debugging programs that run on
+another machine---the target). You specify a cross-debugging target by
+giving the @samp{--target=@var{target}} option to @code{configure}.
+
+When you run @code{make} to build a program or library, you must run
+it in a configured directory---whatever directory you were in when you
+called @code{configure} (or one of its subdirectories).
+
+The @code{Makefile} generated by @code{configure} for each source
+directory also runs recursively. If you type @code{make} in a source
+directory such as @file{gdb-_GDB_VN__} (or in a separate configured
+directory configured with @samp{--srcdir=@var{path}/gdb-_GDB_VN__}), you
+will build all the required libraries, then build GDB.
+
+When you have multiple hosts or targets configured in separate
+directories, you can run @code{make} on them in parallel (for example,
+if they are NFS-mounted on each of the hosts); they will not interfere
+with each other.
+
+@node Config Names, configure Options, Separate Objdir, Installing GDB
+@section Specifying Names for Hosts and Targets
+
+The specifications used for hosts and targets in the @code{configure}
+script are based on a three-part naming scheme, but some short predefined
+aliases are also supported. The full naming scheme encodes three pieces
+of information in the following pattern:
+
+@example
+@var{architecture}-@var{vendor}-@var{os}
+@end example
+
+For example, you can use the alias @code{sun4} as a @var{host} argument
+or in a @code{--target=@var{target}} option, but the equivalent full name
+is @samp{sparc-sun-sunos4}.
+
+The @code{configure} script accompanying GDB does not provide
+any query facility to list all supported host and target names or
+aliases. @code{configure} calls the Bourne shell script
+@code{config.sub} to map abbreviations to full names; you can read the
+script, if you wish, or you can use it to test your guesses on
+abbreviations---for example:
+
+@example
+% sh config.sub sun4
+sparc-sun-sunos411
+% sh config.sub sun3
+m68k-sun-sunos411
+% sh config.sub decstation
+mips-dec-ultrix42
+% sh config.sub hp300bsd
+m68k-hp-bsd
+% sh config.sub i386v
+i386-unknown-sysv
+% sh config.sub i786v
+Invalid configuration `i786v': machine `i786v' not recognized
+@end example
+
+@noindent
+@code{config.sub} is also distributed in the GDB source
+directory (@file{gdb-_GDB_VN__}, for version _GDB_VN__).
+
+@node configure Options, , Config Names, Installing GDB
+@section @code{configure} Options
+
+Here is a summary of all the @code{configure} options and arguments that
+you might use for building GDB:
+
+@example
+configure @r{[}--srcdir=@var{path}@r{]}
+ @r{[}--norecursion@r{]} @r{[}--rm@r{]}
+ @r{[}--target=@var{target}@r{]} @var{host}
@end example
@noindent
-is all that's required to install _GDBN__ on a Sun 3 running SunOS 4.
+You may introduce options with a single @samp{-} rather than
+@samp{--} if you prefer; but you may abbreviate option names if you use
+@samp{--}.
@table @code
-@kindex config.gdb
-@item config.gdb @var{machine}
-@itemx config.gdb -srcdir=@var{dir} @var{machine}
-This is the most usual way of configuring _GDBN__; to debug programs running
-on the same machine as _GDBN__ itself. If you wish to build the _GDBN__ binaries
-in a completely different directory from the sources, specify a path to
-the source directory using the @samp{-srcdir} option.
-
-@item config.gdb -host
-@cindex host environments
-Display a list of supported host environments for _GDBN__.
-
-@item config.gdb @var{host} @var{target}
-@itemx config.gdb -srcdir=@var{dir} @var{host} @var{target}
-@cindex cross-debugging
-_GDBN__ can also be used as a cross-debugger, running on a machine of one
-type while debugging a program running on a machine of another type.
-You configure it this way by specifying first the @var{host}, then the
-@var{target} environment on the @code{config.gdb} argument list; the
-@var{host} is where _GDBN__ runs, and the @var{target} is where your program
-runs. @xref{Remote}. Again, you can use @samp{-srcdir} to specify a
-path to the _GDBN__ source.
-
-@item config.gdb -target
-@cindex target environments
-Display a list of supported target environments for _GDBN__.
+@item --srcdir=@var{path}
+@strong{Warning: using this option requires GNU @code{make}, or another
+@code{make} that implements the @code{VPATH} feature.}@*
+Use this option to make configurations in directories separate from the
+GDB source directories. Among other things, you can use this to
+build (or maintain) several configurations simultaneously, in separate
+directories. @code{configure} writes configuration specific files in
+the current directory, but arranges for them to use the source in the
+directory @var{path}. @code{configure} will create directories under
+the working directory in parallel to the source directories below
+@var{path}.
+
+@item --norecursion
+Configure only the directory level where @code{configure} is executed; do not
+propagate configuration to subdirectories.
+
+@item --rm
+Remove the configuration that the other arguments specify.
+
+@c This does not work (yet if ever). FIXME.
+@c @item --parse=@var{lang} @dots{}
+@c Configure the GDB expression parser to parse the listed languages.
+@c @samp{all} configures GDB for all supported languages. To get a
+@c list of all supported languages, omit the argument. Without this
+@c option, GDB is configured to parse all supported languages.
+
+@item --target=@var{target}
+Configure GDB for cross-debugging programs running on the specified
+@var{target}. Without this option, GDB is configured to debug
+programs that run on the same machine (@var{host}) as GDB itself.
+
+There is no convenient way to generate a list of all available targets.
+
+@item @var{host} @dots{}
+Configure GDB to run on the specified @var{host}.
+
+There is no convenient way to generate a list of all available hosts.
@end table
-@node License,,,
+@noindent
+@code{configure} accepts other options, for compatibility with
+configuring other GNU tools recursively; but these are the only
+options that affect GDB or its supporting libraries.
+
+@node Copying, Index, Installing GDB, Top
@unnumbered GNU GENERAL PUBLIC LICENSE
-@center Version 1, February 1989
+@center Version 2, June 1991
@display
-Copyright @copyright{} 1989 Free Software Foundation, Inc.
+Copyright @copyright{} 1989, 1991 Free Software Foundation, Inc.
675 Mass Ave, Cambridge, MA 02139, USA
Everyone is permitted to copy and distribute verbatim copies
@unnumberedsec Preamble
- The license agreements of most software companies try to keep users
-at the mercy of those companies. By contrast, our General Public
+ The licenses for most software are designed to take away your
+freedom to share and change it. By contrast, the GNU General Public
License is intended to guarantee your freedom to share and change free
-software---to make sure the software is free for all its users. The
-General Public License applies to the Free Software Foundation's
-software and to any other program whose authors commit to using it.
-You can use it for your programs, too.
+software---to make sure the software is free for all its users. This
+General Public License applies to most of the Free Software
+Foundation's software and to any other program whose authors commit to
+using it. (Some other Free Software Foundation software is covered by
+the GNU Library General Public License instead.) You can apply it to
+your programs, too.
When we speak of free software, we are referring to freedom, not
-price. Specifically, the General Public License is designed to make
-sure that you have the freedom to give away or sell copies of free
-software, that you receive source code or can get it if you want it,
-that you can change the software or use pieces of it in new free
-programs; and that you know you can do these things.
+price. Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+this service if you wish), that you receive source code or can get it
+if you want it, that you can change the software or use pieces of it
+in new free programs; and that you know you can do these things.
To protect your rights, we need to make restrictions that forbid
anyone to deny you these rights or to ask you to surrender the rights.
These restrictions translate to certain responsibilities for you if you
distribute copies of the software, or if you modify it.
- For example, if you distribute copies of a such a program, whether
+ For example, if you distribute copies of such a program, whether
gratis or for a fee, you must give the recipients all the rights that
you have. You must make sure that they, too, receive or can get the
-source code. And you must tell them their rights.
+source code. And you must show them these terms so they know their
+rights.
We protect your rights with two steps: (1) copyright the software, and
(2) offer you this license which gives you legal permission to copy,
that any problems introduced by others will not reflect on the original
authors' reputations.
+ Finally, any free program is threatened constantly by software
+patents. We wish to avoid the danger that redistributors of a free
+program will individually obtain patent licenses, in effect making the
+program proprietary. To prevent this, we have made it clear that any
+patent must be licensed for everyone's free use or not licensed at all.
+
The precise terms and conditions for copying, distribution and
modification follow.
@iftex
-@unnumberedsec TERMS AND CONDITIONS
+@unnumberedsec TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
@end iftex
@ifinfo
-@center TERMS AND CONDITIONS
+@center TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
@end ifinfo
@enumerate
@item
-This License Agreement applies to any program or other work which
-contains a notice placed by the copyright holder saying it may be
-distributed under the terms of this General Public License. The
-``Program'', below, refers to any such program or work, and a ``work based
-on the Program'' means either the Program or any work containing the
-Program or a portion of it, either verbatim or with modifications. Each
-licensee is addressed as ``you''.
+This License applies to any program or other work which contains
+a notice placed by the copyright holder saying it may be distributed
+under the terms of this General Public License. The ``Program'', below,
+refers to any such program or work, and a ``work based on the Program''
+means either the Program or any derivative work under copyright law:
+that is to say, a work containing the Program or a portion of it,
+either verbatim or with modifications and/or translated into another
+language. (Hereinafter, translation is included without limitation in
+the term ``modification''.) Each licensee is addressed as ``you''.
+
+Activities other than copying, distribution and modification are not
+covered by this License; they are outside its scope. The act of
+running the Program is not restricted, and the output from the Program
+is covered only if its contents constitute a work based on the
+Program (independent of having been made by running the Program).
+Whether that is true depends on what the Program does.
@item
-You may copy and distribute verbatim copies of the Program's source
-code as you receive it, in any medium, provided that you conspicuously and
-appropriately publish on each copy an appropriate copyright notice and
-disclaimer of warranty; keep intact all the notices that refer to this
-General Public License and to the absence of any warranty; and give any
-other recipients of the Program a copy of this General Public License
-along with the Program. You may charge a fee for the physical act of
-transferring a copy.
+You may copy and distribute verbatim copies of the Program's
+source code as you receive it, in any medium, provided that you
+conspicuously and appropriately publish on each copy an appropriate
+copyright notice and disclaimer of warranty; keep intact all the
+notices that refer to this License and to the absence of any warranty;
+and give any other recipients of the Program a copy of this License
+along with the Program.
-@item
-You may modify your copy or copies of the Program or any portion of
-it, and copy and distribute such modifications under the terms of Paragraph
-1 above, provided that you also do the following:
+You may charge a fee for the physical act of transferring a copy, and
+you may at your option offer warranty protection in exchange for a fee.
-@itemize @bullet
@item
-cause the modified files to carry prominent notices stating that
-you changed the files and the date of any change; and
+You may modify your copy or copies of the Program or any portion
+of it, thus forming a work based on the Program, and copy and
+distribute such modifications or work under the terms of Section 1
+above, provided that you also meet all of these conditions:
+@enumerate a
@item
-cause the whole of any work that you distribute or publish, that
-in whole or in part contains the Program or any part thereof, either
-with or without modifications, to be licensed at no charge to all
-third parties under the terms of this General Public License (except
-that you may choose to grant warranty protection to some or all
-third parties, at your option).
+You must cause the modified files to carry prominent notices
+stating that you changed the files and the date of any change.
@item
-If the modified program normally reads commands interactively when
-run, you must cause it, when started running for such interactive use
-in the simplest and most usual way, to print or display an
-announcement including an appropriate copyright notice and a notice
-that there is no warranty (or else, saying that you provide a
-warranty) and that users may redistribute the program under these
-conditions, and telling the user how to view a copy of this General
-Public License.
+You must cause any work that you distribute or publish, that in
+whole or in part contains or is derived from the Program or any
+part thereof, to be licensed as a whole at no charge to all third
+parties under the terms of this License.
@item
-You may charge a fee for the physical act of transferring a
-copy, and you may at your option offer warranty protection in
-exchange for a fee.
-@end itemize
+If the modified program normally reads commands interactively
+when run, you must cause it, when started running for such
+interactive use in the most ordinary way, to print or display an
+announcement including an appropriate copyright notice and a
+notice that there is no warranty (or else, saying that you provide
+a warranty) and that users may redistribute the program under
+these conditions, and telling the user how to view a copy of this
+License. (Exception: if the Program itself is interactive but
+does not normally print such an announcement, your work based on
+the Program is not required to print an announcement.)
+@end enumerate
-Mere aggregation of another independent work with the Program (or its
-derivative) on a volume of a storage or distribution medium does not bring
-the other work under the scope of these terms.
+These requirements apply to the modified work as a whole. If
+identifiable sections of that work are not derived from the Program,
+and can be reasonably considered independent and separate works in
+themselves, then this License, and its terms, do not apply to those
+sections when you distribute them as separate works. But when you
+distribute the same sections as part of a whole which is a work based
+on the Program, the distribution of the whole must be on the terms of
+this License, whose permissions for other licensees extend to the
+entire whole, and thus to each and every part regardless of who wrote it.
+
+Thus, it is not the intent of this section to claim rights or contest
+your rights to work written entirely by you; rather, the intent is to
+exercise the right to control the distribution of derivative or
+collective works based on the Program.
+
+In addition, mere aggregation of another work not based on the Program
+with the Program (or with a work based on the Program) on a volume of
+a storage or distribution medium does not bring the other work under
+the scope of this License.
@item
-You may copy and distribute the Program (or a portion or derivative of
-it, under Paragraph 2) in object code or executable form under the terms of
-Paragraphs 1 and 2 above provided that you also do one of the following:
+You may copy and distribute the Program (or a work based on it,
+under Section 2) in object code or executable form under the terms of
+Sections 1 and 2 above provided that you also do one of the following:
-@itemize @bullet
+@enumerate a
@item
-accompany it with the complete corresponding machine-readable
-source code, which must be distributed under the terms of
-Paragraphs 1 and 2 above; or,
+Accompany it with the complete corresponding machine-readable
+source code, which must be distributed under the terms of Sections
+1 and 2 above on a medium customarily used for software interchange; or,
@item
-accompany it with a written offer, valid for at least three
-years, to give any third party free (except for a nominal charge
-for the cost of distribution) a complete machine-readable copy of the
-corresponding source code, to be distributed under the terms of
-Paragraphs 1 and 2 above; or,
+Accompany it with a written offer, valid for at least three
+years, to give any third party, for a charge no more than your
+cost of physically performing source distribution, a complete
+machine-readable copy of the corresponding source code, to be
+distributed under the terms of Sections 1 and 2 above on a medium
+customarily used for software interchange; or,
@item
-accompany it with the information you received as to where the
-corresponding source code may be obtained. (This alternative is
+Accompany it with the information you received as to the offer
+to distribute corresponding source code. (This alternative is
allowed only for noncommercial distribution and only if you
-received the program in object code or executable form alone.)
-@end itemize
+received the program in object code or executable form with such
+an offer, in accord with Subsection b above.)
+@end enumerate
-Source code for a work means the preferred form of the work for making
-modifications to it. For an executable file, complete source code means
-all the source code for all modules it contains; but, as a special
-exception, it need not include source code for modules which are standard
-libraries that accompany the operating system on which the executable
-file runs, or for standard header files or definitions files that
-accompany that operating system.
+The source code for a work means the preferred form of the work for
+making modifications to it. For an executable work, complete source
+code means all the source code for all modules it contains, plus any
+associated interface definition files, plus the scripts used to
+control compilation and installation of the executable. However, as a
+special exception, the source code distributed need not include
+anything that is normally distributed (in either source or binary
+form) with the major components (compiler, kernel, and so on) of the
+operating system on which the executable runs, unless that component
+itself accompanies the executable.
+
+If distribution of executable or object code is made by offering
+access to copy from a designated place, then offering equivalent
+access to copy the source code from the same place counts as
+distribution of the source code, even though third parties are not
+compelled to copy the source along with the object code.
@item
-You may not copy, modify, sublicense, distribute or transfer the
-Program except as expressly provided under this General Public License.
-Any attempt otherwise to copy, modify, sublicense, distribute or transfer
-the Program is void, and will automatically terminate your rights to use
-the Program under this License. However, parties who have received
-copies, or rights to use copies, from you under this General Public
-License will not have their licenses terminated so long as such parties
-remain in full compliance.
+You may not copy, modify, sublicense, or distribute the Program
+except as expressly provided under this License. Any attempt
+otherwise to copy, modify, sublicense or distribute the Program is
+void, and will automatically terminate your rights under this License.
+However, parties who have received copies, or rights, from you under
+this License will not have their licenses terminated so long as such
+parties remain in full compliance.
@item
-By copying, distributing or modifying the Program (or any work based
-on the Program) you indicate your acceptance of this license to do so,
-and all its terms and conditions.
+You are not required to accept this License, since you have not
+signed it. However, nothing else grants you permission to modify or
+distribute the Program or its derivative works. These actions are
+prohibited by law if you do not accept this License. Therefore, by
+modifying or distributing the Program (or any work based on the
+Program), you indicate your acceptance of this License to do so, and
+all its terms and conditions for copying, distributing or modifying
+the Program or works based on it.
@item
Each time you redistribute the Program (or any work based on the
-Program), the recipient automatically receives a license from the original
-licensor to copy, distribute or modify the Program subject to these
-terms and conditions. You may not impose any further restrictions on the
-recipients' exercise of the rights granted herein.
+Program), the recipient automatically receives a license from the
+original licensor to copy, distribute or modify the Program subject to
+these terms and conditions. You may not impose any further
+restrictions on the recipients' exercise of the rights granted herein.
+You are not responsible for enforcing compliance by third parties to
+this License.
+
+@item
+If, as a consequence of a court judgment or allegation of patent
+infringement or for any other reason (not limited to patent issues),
+conditions are imposed on you (whether by court order, agreement or
+otherwise) that contradict the conditions of this License, they do not
+excuse you from the conditions of this License. If you cannot
+distribute so as to satisfy simultaneously your obligations under this
+License and any other pertinent obligations, then as a consequence you
+may not distribute the Program at all. For example, if a patent
+license would not permit royalty-free redistribution of the Program by
+all those who receive copies directly or indirectly through you, then
+the only way you could satisfy both it and this License would be to
+refrain entirely from distribution of the Program.
+
+If any portion of this section is held invalid or unenforceable under
+any particular circumstance, the balance of the section is intended to
+apply and the section as a whole is intended to apply in other
+circumstances.
+
+It is not the purpose of this section to induce you to infringe any
+patents or other property right claims or to contest validity of any
+such claims; this section has the sole purpose of protecting the
+integrity of the free software distribution system, which is
+implemented by public license practices. Many people have made
+generous contributions to the wide range of software distributed
+through that system in reliance on consistent application of that
+system; it is up to the author/donor to decide if he or she is willing
+to distribute software through any other system and a licensee cannot
+impose that choice.
+
+This section is intended to make thoroughly clear what is believed to
+be a consequence of the rest of this License.
+
+@item
+If the distribution and/or use of the Program is restricted in
+certain countries either by patents or by copyrighted interfaces, the
+original copyright holder who places the Program under this License
+may add an explicit geographical distribution limitation excluding
+those countries, so that distribution is permitted only in or among
+countries not thus excluded. In such case, this License incorporates
+the limitation as if written in the body of this License.
@item
The Free Software Foundation may publish revised and/or new versions
address new problems or concerns.
Each version is given a distinguishing version number. If the Program
-specifies a version number of the license which applies to it and ``any
+specifies a version number of this License which applies to it and ``any
later version'', you have the option of following the terms and conditions
either of that version or of any later version published by the Free
Software Foundation. If the Program does not specify a version number of
-the license, you may choose any version ever published by the Free Software
+this License, you may choose any version ever published by the Free Software
Foundation.
@item
REPAIR OR CORRECTION.
@item
-IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL
-ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
+IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
-INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES
-ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT
-LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES
-SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE
-WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN
-ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
+INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
+OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
+TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
+YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
+PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGES.
@end enumerate
@iftex
@unnumberedsec Applying These Terms to Your New Programs
If you develop a new program, and you want it to be of the greatest
-possible use to humanity, the best way to achieve this is to make it
-free software which everyone can redistribute and change under these
-terms.
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
- To do so, attach the following notices to the program. It is safest to
-attach them to the start of each source file to most effectively convey
-the exclusion of warranty; and each file should have at least the
-``copyright'' line and a pointer to where the full notice is found.
+ To do so, attach the following notices to the program. It is safest
+to attach them to the start of each source file to most effectively
+convey the exclusion of warranty; and each file should have at least
+the ``copyright'' line and a pointer to where the full notice is found.
@smallexample
-@var{one line to give the program's name and a brief idea of what it does.}
+@var{one line to give the program's name and an idea of what it does.}
Copyright (C) 19@var{yy} @var{name of author}
-This program is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 1, or (at your option)
-any later version.
+This program is free software; you can redistribute it and/or
+modify it under the terms of the GNU General Public License
+as published by the Free Software Foundation; either version 2
+of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
-along with this program; if not, write to the Free Software
-Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+along with this program; if not, write to the
+Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA.
@end smallexample
Also add information on how to contact you by electronic and paper mail.
@smallexample
Gnomovision version 69, Copyright (C) 19@var{yy} @var{name of author}
-Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
-This is free software, and you are welcome to redistribute it
-under certain conditions; type `show c' for details.
+Gnomovision comes with ABSOLUTELY NO WARRANTY; for details
+type `show w'. This is free software, and you are welcome
+to redistribute it under certain conditions; type `show c'
+for details.
@end smallexample
-The hypothetical commands `show w' and `show c' should show the
-appropriate parts of the General Public License. Of course, the
-commands you use may be called something other than `show w' and `show
-c'; they could even be mouse-clicks or menu items---whatever suits your
-program.
+The hypothetical commands @samp{show w} and @samp{show c} should show
+the appropriate parts of the General Public License. Of course, the
+commands you use may be called something other than @samp{show w} and
+@samp{show c}; they could even be mouse-clicks or menu items---whatever
+suits your program.
You should also get your employer (if you work as a programmer) or your
school, if any, to sign a ``copyright disclaimer'' for the program, if
necessary. Here is a sample; alter the names:
-@smallexample
-Yoyodyne, Inc., hereby disclaims all copyright interest in the
-program `Gnomovision' (a program to direct compilers to make passes
-at assemblers) written by James Hacker.
+@example
+Yoyodyne, Inc., hereby disclaims all copyright
+interest in the program `Gnomovision'
+(which makes passes at compilers) written
+by James Hacker.
@var{signature of Ty Coon}, 1 April 1989
Ty Coon, President of Vice
-@end smallexample
-
-That's all there is to it!
-
-@node Commands, Concepts, License, Top
-@unnumbered Command Index
+@end example
-@printindex ky
+This General Public License does not permit incorporating your program into
+proprietary programs. If your program is a subroutine library, you may
+consider it more useful to permit linking proprietary applications with the
+library. If this is what you want to do, use the GNU Library General
+Public License instead of this License.
-@node Concepts, , Commands, Top
+@node Index, , Copying, Top
@unnumbered Index
@printindex cp
+@tex
+% I think something like @colophon should be in texinfo. In the
+% meantime:
+\long\def\colophon{\hbox to0pt{}\vfill
+\centerline{The body of this manual is set in}
+\centerline{\fontname\tenrm,}
+\centerline{with headings in {\bf\fontname\tenbf}}
+\centerline{and examples in {\tt\fontname\tentt}.}
+\centerline{{\it\fontname\tenit\/},}
+\centerline{{\bf\fontname\tenbf}, and}
+\centerline{{\sl\fontname\tensl\/}}
+\centerline{are used for emphasis.}\vfill}
+\page\colophon
+@end tex
+
@contents
@bye
projects / binutils.git / blobdiff