+_dnl__ -*-Texinfo-*-
+_dnl__ Copyright (c) 1988 1989 1990 1991 Free Software Foundation, Inc.
\input texinfo
@setfilename _GDBP__.info
+@c $Id$
+@c THIS MANUAL REQUIRES TEXINFO-2 macros and info-makers to format properly.
@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 with all configurations, from wherever you got this).
_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).
+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
+_1__
+will produce (assuming your path finds either GNU m4 >= 0.84, 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).
_fi__(0)
+_include__(gdbVN.m4)
+@tex
+\def\$#1${{#1}} % Kluge: collect RCS revision info without $...$
+\xdef\manvers{\$Revision$} % For use in headers, footers too
+@end tex
@c
-@synindex ky cp
+@syncodeindex 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 Fri Sep 20 16:10:52 1991 John Gilmore (gnu at cygnus.com)
@c Sat Dec 22 02:51:40 1990 John Gilmore (gnu at cygint)
@ifinfo
This file documents the GNU debugger _GDBN__.
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
+@c @smallbook
@setchapternewpage odd
_if__(_GENERIC__)
-@settitle Using _GDBN__ (v4.0)
+@settitle Using _GDBN__ (<v>_GDB_VN__)
_fi__(_GENERIC__)
_if__(!_GENERIC__)
-@settitle Using _GDBN__ v4.0 (_HOST__)
+@settitle Using _GDBN__ <v>_GDB_VN__ (_HOST__)
_fi__(!_GENERIC__)
@iftex
-@c @finalout
+@finalout
@end iftex
@titlepage
@title{Using _GDBN__}
_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 @subtitle Third Edition---_GDBN__ version _GDB_VN__
+@subtitle _GDBN__ version _GDB_VN__
+@subtitle July 1991
+@author{Richard M. Stallman@qquad @hfill Free Software Foundation}
+@author{Roland H. Pesch@qquad @hfill Cygnus Support}
@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 rms\@ai.mit.edu, pesch\@cygnus.com\par
+\hfill {\it Using _GDBN__}, \manvers\par
\hfill \TeX{}info \texinfoversion\par
}
@end tex
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)
+@node Top, Summary, (dir), (dir)
+@ifinfo
+This file describes version _GDB_VN__ of GDB, the GNU symbolic debugger.
+@end ifinfo
+
+@menu
+* Summary:: Summary of _GDBN__
+* New Features:: New Features in _GDBN__ version _GDB_VN__
+* 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::
+* Installing _GDBN__:: Installing _GDBN__
+* Copying:: GNU GENERAL PUBLIC LICENSE
+* Index:: Index
+
+ --- The Detailed Node Listing ---
+
+Summary of _GDBN__
+
+* Free Software:: Free Software
+* Contributors:: Contributors to _GDBN__
+
+Getting In and Out of _GDBN__
+
+* Starting _GDBN__:: Starting _GDBN__
+* Leaving _GDBN__:: Leaving _GDBN__
+* Shell Commands:: Shell Commands
+
+Starting _GDBN__
+
+* File Options:: Choosing Files
+* Mode Options:: Choosing Modes
+
+_GDBN__ Commands
+
+* Command Syntax:: Command Syntax
+* 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
+
+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
+* Builtin 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 the 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
+
+* Subdirectories:: Configuration subdirectories
+* Config Names:: Specifying names for hosts and targets
+* configure Options:: Summary of options for configure
+* Formatting Documentation:: How to format and print GDB documentation
+@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
_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
+
+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.
-_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.
+@menu
+* Free Software:: Free Software
+* Contributors:: Contributors to GDB
+@end menu
-@node Free Software,,,
+@node Free Software, Contributors, Summary, Summary
@unnumberedsec Free Software
-_GDBN__ is Free Software, protected by the GNU General Public License (GPL).
+_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
you have these freedoms and that you can't take these freedoms away
from anyone else.
-For full details, @pxref{License}.
+@c FIXME: (passim) go through all xrefs, expanding to use text headings
+For full details, @pxref{Copying}.
+@node Contributors, , Free Software, Summary
+@unnumberedsec Contributors to GDB
-@node New Features, Invocation, Top, Top
-@unnumbered New Features in _GDBN__ version 4.0
+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.
-@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.
+Changes much prior to version 2.0 are lost in the mists of time.
-@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.
+@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
-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.
+So that they may not regard their long labor as thankless, we
+particularly thank those who shepherded GDB through major releases: John
+Gilmore (releases _GDB_VN__, 4.0); Jim Kingdon (releases 3.9, 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 _GDB_VN__ uses the BFD subroutine library to examine multiple
+object-file formats; BFD was a joint project of V. Gumby
+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.
+
+@node New Features, Sample Session, Summary, Top
+@unnumbered New Features since _GDBN__ 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;
+_GDBN__ 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, _GDBN__ 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
+_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 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
+_GDBN__ 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 _GDBN__ as either a native debugger or a
+cross-debugger. @xref{Installing _GDBN__} for details on how to
+configure and on what architectures are now available.
+
+@item Interaction
+The user interface to _GDBN__'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
-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.
-@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++
+_GDBN__ 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}: _GDBN__
+can break when an exception is raised, before the stack is peeled back
+to the exception handler's context.
+
+@item Modula-2
+_GDBN__ 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 _GDBN__ and the GNU Modula-2
+compiler will continue through the fall of 1991 and 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 _GDBN__ 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 _GDBN__ itself.
+@xref{Renamed Commands}, for details on what commands were renamed.
+
+@item Shared Libraries
+_GDBN__ _GDB_VN__ can debug programs and core files that use SunOS shared
+libraries. You can load symbols from a shared library with the command
+@code{sharedlibrary} (@pxref{Files}).
+
+@item Reference Card
+_GDBN__ _GDB_VN__ has a reference card; @xref{Formatting Documentation} for
+instructions on printing it.
+
+@item Work in Progress
+Kernel debugging for BSD and Mach systems; Tahoe and HPPA architecture
+support.
-@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.
+@end table
-@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.
+@node Sample Session, Invocation, New Features, Top
+@chapter A Sample _GDBN__ Session
-@item
-SHARED LIBRARIES: _GDBN__ 4.0 supports SunOS shared libraries.
+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
-WORK IN PROGRESS: kernel debugging for BSD and Mach systems; Tahoe and
-HPPA architecture support.
+@iftex
+In this sample session, we emphasize user input like this: @i{input},
+to make it easier to pick out from the surrounding output.
+@end iftex
-@end itemize
+@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} builtin @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}:
+
+@smallexample
+$ @i{cd gnu/m4}
+$ @i{./m4}
+@i{define(foo,0000)}
+
+@i{foo}
+0000
+@i{define(bar,defn(`foo'))}
+
+@i{bar}
+0000
+@i{changequote(<QUOTE>,<UNQUOTE>)}
+
+@i{define(baz,defn(<QUOTE>foo<UNQUOTE>))}
+@i{baz}
+@i{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
+$ @i{_GDBP__ m4}
+GDB is free software and you are welcome to distribute copies of it
+ under certain conditions; type "info copying" to see the conditions.
+There is absolutely no warranty for GDB; type "info warranty" for details.
+GDB _GDB_VN__, Copyright 1991 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
+then tell _GDBN__ to use a narrower display width than usual, so
+that examples will fit in this manual.
+
+@smallexample
+(_GDBP__) @i{set width 70}
+@end smallexample
+
+@noindent
+Let's see how the @code{m4} builtin @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__) @i{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__) @i{run}
+Starting program: /work/Editorial/gdb/gnu/m4/m4
+@i{define(foo,0000)}
+
+@i{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
+@i{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__) @i{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__) @i{s}
+set_quotes (lq=0x34c78 "<QUOTE>", rq=0x34c88 "<UNQUOTE>")
+ at input.c:530
+530 if (lquote != def_lquote)
+@end smallexample
+
+@noindent
+The summary display showing the subroutine where @code{m4} is now
+suspended (and its arguments) is called a stack frame display. We can
+use the @code{backtrace} command (which can also be spelled @code{bt}),
+to see where we are in the stack: it displays a stack frame for each
+active subroutine.
+
+@smallexample
+(_GDBP__) @i{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__) @i{s}
+0x3b5c 532 if (rquote != def_rquote)
+(_GDBP__) @i{s}
+0x3b80 535 lquote = (lq == nil || *lq == '\0') ? def_lquote :\
+ xstrdup(lq);
+(_GDBP__) @i{n}
+536 rquote = (rq == nil || *rq == '\0') ? def_rquote : xstrdup\
+(rq);
+(_GDBP__) @i{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__) @i{p lquote}
+$1 = 0x35d40 "<QUOTE>"
+(_GDBP__) @i{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__) @i{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__) @i{n}
+539 len_rquote = strlen(lquote);
+(_GDBP__) @i{n}
+540 @}
+(_GDBP__) @i{p len_lquote}
+$3 = 9
+(_GDBP__) @i{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__) p len_lquote=strlen(lquote)
+$5 = 7
+(_GDBP__) 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__) @i{c}
+Continuing.
+
+@i{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
+@i{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__) @i{quit}
+_1__@end smallexample
-@node Invocation, User Interface, New Features, Top
-@chapter Starting _GDBN__
+@node Invocation, Commands, Sample Session, Top
+@chapter Getting In and Out of _GDBN__
-_GDBN__ is invoked with the shell command @samp{_GDBP__}. Once started, it reads
-commands from the terminal until you tell it to exit.
+@menu
+* Starting _GDBN__:: Starting _GDBN__
+* Leaving _GDBN__:: Leaving _GDBN__
+* Shell Commands:: Shell Commands
+@end menu
+
+@node Starting _GDBN__, Leaving _GDBN__, Invocation, Invocation
+@section Starting _GDBN__
+
+_GDBN__ is invoked with the shell command @code{_GDBP__}. Once started,
+it reads commands from the terminal until you tell it to exit.
-The most usual way to start _GDBN__ is with one argument or two, specifying
-an executable program as the argument:
+You can run @code{_GDBP__} with no arguments or options; but the most
+usual way to start _GDBN__ is with one argument or two, specifying an
+executable program as the argument:
@example
_GDBP__ program
@end example
@noindent
-or you can start with both an executable program and a core file specified:
+You can also start with both an executable program and a core file specified:
@example
_GDBP__ program core
@end example
-You can get more detailed control over how _GDBN__ starts up using some of
-the command-line options.
+You can, instead, specify a process ID as a second argument, if you want
+to debug a running process:
+@example
+_GDBP__ 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).
+
+@noindent
+You can further control how _GDBN__ starts up by using command-line
+options. _GDBN__ itself can remind you of the options available:
+@example
+_GDBP__ -help
+@end example
+@noindent
+will 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.
-@node File Options, Mode Options, Invocation, Invocation
-@section Options and Arguments to Choose Files
+@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, Starting _GDBN__, Starting _GDBN__
+@subsection Choosing Files
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.
+second, if any, is equivalent to a @samp{-c} option. Many options have
+both long and short forms; both are shown here. The long forms are also
+recognized 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.
@end table
-@node Mode Options, Remote i960-Nindy, File Options, Invocation
-@section Options to Choose Modes
+_if__(!_GENERIC__)
+@node Mode Options, Mode Options, File Options, Starting _GDBN__
+_fi__(!_GENERIC__)
+_if__(_GENERIC__)
+@node Mode Options, , File Options, Starting _GDBN__
+_fi__(_GENERIC__)
+@subsection Choosing Modes
@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}.
-@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.
(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.
+
@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
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
-
-_if__(_I960__)
-@node i960-Nindy Remote,,,
-@section _GDBN__ with a Remote Intel 960 (Nindy)
-
-``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:
-
-@itemize @bullet
-@item
-Through command line options specifying device, baud rate, and protocol;
-
-@item
-By responding to a prompt on startup;
-
-@item
-By using the @samp{target} command at any point during your _GDBN__ session.
-@end itemize
-
-@node Nindy Startup,,,
-@subsection Startup with Nindy
-
-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}).
+Set the line speed (baud rate or bits per second) of any serial
+interface used by _GDBN__ for remote debugging.
-@node Nindy Options,,,
-@subsection Options for Nindy
+@item -tty=@var{device}
+Run using @var{device} for your program's standard input and output.
+@c FIXME: kingdon thinks there's more to -tty. Investigate.
+@end table
-These are the startup options for beginning your _GDBN__ session with a
-Nindy-960 board attached:
+_if__(!_GENERIC__)
+_include__(gdbinv-s.m4)
+_fi__(!_GENERIC__)
+@node Leaving _GDBN__, Shell Commands, Starting _GDBN__, Invocation
+@section Leaving _GDBN__
+@cindex exiting _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.
+@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
-@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
+@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 -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.
+If you've been using _GDBN__ to control an attached process or device,
+you can release it with the @code{detach} command; @pxref{Attach}.
-@quotation
-@emph{Warning:} Many target systems do not have the hardware that this
-requires; it only works with a few boards.
-@end quotation
+@node Shell Commands, , Leaving _GDBN__, Invocation
+@section Shell Commands
+If you need to execute occasional shell commands during your
+debugging session, there's no need to leave or suspend _GDBN__; you can
+just use the @code{shell} command.
+@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
-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
+The utility @code{make} is often needed in development environments.
+You don't have to use the @code{shell} command for this purpose in _GDBN__:
-@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
+@table @code
+@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
-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__)
+@node Commands, Running, Invocation, Top
+@chapter _GDBN__ Commands
-@node User Interface, Files, Invocation, Top
-@chapter _GDBN__ Commands and Displays
+@menu
+* Command Syntax:: Command Syntax
+* Help:: Getting Help
+@end menu
+@node Command Syntax, Help, 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}.
-
-@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.
+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
+@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's 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.
+A line of input starting with @kbd{#} is a comment; it does nothing.
This is useful mainly in command files (@xref{Command Files}).
+@node Help, , Command Syntax, Commands
+@section Getting Help
@cindex online documentation
@kindex help
+You can always ask _GDBN__ itself for information on its commands, using the
+command @code{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
+@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:
+@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
-@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.
+@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}:
+@smallexample
+(_GDBP__) help status
+Status inquiries.
-@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
+List of commands:
-@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.
+show -- Generic command for showing things set with "set"
+info -- Generic command for printing status
-@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.
+Type "help" followed by command name for full documentation.
+Command name abbreviations are allowed if unambiguous.
+(_GDBP__)
+@end smallexample
-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}.
+@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
+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.
+@c FIXME: @pxref{Index} used to be here, but even though it shows up in
+@c FIXME...the 'aux' file with a pageno the xref can't find it.
+
+@c @group
@table @code
-@kindex set editing
-@cindex editing
-@item set editing
-@itemx set editing on
-Enable command line editing (enabled by default).
+@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've set (@code{info breakpoints}).
+You can get a complete list of the @code{info} sub-commands with
+@w{@code{help info}}.
-@item set editing off
-Disable command line editing.
+@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}.
-@kindex show editing
-@item show editing
-Show whether command line editing is enabled.
+@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 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.
+Here are three miscellaneous @code{show} subcommands, all of which are
+exceptional in lacking corresponding @code{set} commands:
-@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.
+@table @code
+@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're 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
-@item set history write off
-Make _GDBN__ stop recording command history in a file.
+@node Running, Stopping, Commands, Top
+@chapter Running Programs Under _GDBN__
-@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
+@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
+@end menu
-@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 Compilation, Starting, Running, Running
+@section Compiling for Debugging
-The commands to control history expansion are:
+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.
-@table @code
+To request debugging information, specify the @samp{-g} option when you run
+the compiler.
-@kindex set history expansion
-@item set history expansion on
-@itemx set history expansion
-Enable history expansion. History expansion is off by default.
+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.
-@item set history expansion off
-Disable history expansion.
+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.
+
+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!).
-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}.
+Older versions of the GNU C compiler 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.
-@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.
+@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.
-@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.
+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
-@end table
+@node Starting, Arguments, Compilation, Running
+@section Starting your Program
+@cindex starting
+@cindex running
@table @code
-@kindex info editing
-@item info editing
-Display the last ten commands in the command history.
+@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}), or using the @code{file} or @code{exec-file}
+command (@pxref{Files}).
+@refill
+@end table
-@item info editing @var{n}
-Print ten commands centered on command number @var{n}.
+On targets that support processes, @code{run} creates an inferior
+process and makes that process run your program. On other targets,
+@code{run} jumps to the start of the program.
-@item info editing +
-Print ten commands just after the commands last printed.
+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 will only affect
+the program the next time you start it.) This information may be
+divided into four categories:
-@end table
+@table @asis
+@item The @i{arguments.}
+You 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}.@refill
-Occasionally it is useful to execute a shell command from within _GDBN__.
-This can be done with the @samp{shell} command.
+@item The @i{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
+the program. @xref{Environment}.@refill
-@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}.
+@item The @i{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}.
+
+@item The @i{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}.
+
+@cindex pipes
+@emph{Warning:} While input and output redirection work, you can't use
+pipes to pass the output of the program you're debugging to another
+program; if you attempt this, _GDBN__ is likely to wind up debugging the
+wrong program.
@end table
-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__:
+When you issue the @code{run} command, your program begins to execute
+immediately. @xref{Stopping}, 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 the inferior, using the @code{print} or
+@code{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.
-@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{}}.
-@end table
+@node Arguments, Environment, Starting, Running
+@section Your Program's Arguments
-@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.
+@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 the program.
+_GDBN__ uses the shell indicated by your environment variable
+@code{SHELL} if it exists; otherwise, _GDBN__ uses @code{/bin/sh}.
+
+@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
-@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.
+@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.
-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.
+@item show args
+@kindex show args
+Show the arguments to give your program when it is started.
@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 Environment, Working Directory, Arguments, Running
+@section Your Program's Environment
+
+@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 the program with a modified
+environment without having to start _GDBN__ over again.
@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
+@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's 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 don't 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}.
+
+@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 doesn't include leading, trailing
+@c blanks. Gnu asks: does anyone care?
+
+For example, this command:
@example
-set radix 012
-set radix 10.
-set radix 0xa
+set env USER = foo
@end example
@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.
+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 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
-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.
+@node Working Directory, Input/Output, Environment, Running
+@section Your Program's Working Directory
-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}).
-@end ignore
+@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.
-@table @code
-@kindex set verbose
-@item set verbose on
-Enables _GDBN__'s output of certain informational messages.
+The _GDBN__ working directory also serves as a default for the commands
+that specify files for _GDBN__ to operate on. @xref{Files}.
-@item set verbose off
-Disables _GDBN__'s output of certain informational messages.
+@table @code
+@item cd @var{directory}
+@kindex cd
+Set _GDBN__'s working directory to @var{directory}.
-@kindex show verbose
-@item show verbose
-Displays whether @samp{set verbose} is on or off.
+@item pwd
+@kindex pwd
+Print _GDBN__'s working directory.
@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}.
+@node Input/Output, Attach, Working Directory, Running
+@section Your Program's Input and Output
-@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.
+@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.
-@kindex show complaints
-@item show complaints
-Displays how many symbol complaints _GDBN__ is permitted to produce.
+@table @code
+@item info terminal
+@kindex info terminal
+Displays _GDBN__'s recorded information about the terminal modes your
+program is using.
@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
+You can redirect the program's input and/or output using shell
+redirection with the @code{run} command. For example,
-(_GDBP__) run
-The program being debugged has been started already.
-Start it from the beginning? (y or n)
+_0__@example
+run > outfile
+_1__@end example
+
+@noindent
+starts the program, diverting its output to the file @file{outfile}.
+
+@kindex tty
+@cindex controlling terminal
+Another way to specify where the 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,
+
+@example
+tty /dev/ttyb
@end example
-If you're willing to unflinchingly face the consequences of your own
-commands, you can disable this ``feature'':
+@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.
-@table @code
-@kindex set caution
-@cindex flinching
-@cindex stupid questions
-@item set caution off
-Disables cautious questions.
+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.
-@item set caution on
-Enables cautious questions (the default).
+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.
+
+@node Attach, Kill Process, Input/Output, Running
+@section Debugging an Already-Running Process
+@kindex attach
+@cindex attach
-@item show caution
-@kindex show caution
-Displays state of cautious questions.
+@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
-@node Files, Compilation, User Interface, Top
-@chapter Specifying _GDBN__'s Files
+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.
-@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.
-
-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}.
+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}.
-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.
+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 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.
-
-@samp{file} with no argument makes both executable file and symbol
-table become unspecified.
-
-@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.
+@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 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.
+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}).
-@samp{symbol-file} with no argument clears out _GDBN__'s information on your
-program's symbol table.
+@node Kill Process, , Attach, Running
+@c @group
+@section Killing the Child Process
-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__.
+@table @code
+@item kill
+@kindex kill
+Kill the child process in which your program is running under _GDBN__.
+@end table
-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.
+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
-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}).
+On some operating systems, a program can't 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 the program
+outside the debugger.
-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.
+The @code{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 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).
-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.
+@node Stopping, Stack, Running, Top
+@chapter Stopping and Continuing
-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}).
+The principal purpose of using a debugger is so that you can stop your
+program before it terminates; or so that, if the program runs into
+trouble, you can investigate and find out why.
-The messages currently printed, and their meanings, are:
+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 inner block not inside outer block in @var{symbol}
+@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
-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.
+@menu
+* Breakpoints:: Breakpoints, Watchpoints, and Exceptions
+* Continuing and Stepping:: Resuming Execution
+* Signals:: Signals
+@end menu
-@item block at @var{address} out of order
+@node Breakpoints, Continuing and Stepping, Stopping, Stopping
+@section Breakpoints, Watchpoints, and Exceptions
-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}.)
+@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 the program will stop.
+You can set breakpoints with the @code{break} command and its variants
+(@pxref{Set Breaks}), to specify the place where the 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}).
-@item bad block start address patched
+@cindex watchpoints
+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}), 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.
+
+Each breakpoint or watchpoint is assigned a number when it is created;
+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 the program until you enable it again.
-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}
+@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
-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}
+@node Set Breaks, Set Watchpoints, Breakpoints, Breakpoints
+@subsection Setting Breakpoints
-@item unknown symbol type @code{0xNN}
+@kindex break
+@kindex b
+Breakpoints are set with the @code{break} command (abbreviated @code{b}).
-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.
+You have several ways to say where the breakpoint should go.
-@c @item stub type has NULL name
-@c
-@c FIXME, Mike Tiemann needs to write about what this means.
+@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.
-@item const/volatile indicator missing, got 'X'
+@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.
-The symbol information for a C++ type is missing some information that
-the compiler should have output for it.
+@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.
-@item C++ type mismatch between compiler and debugger
+@item break @var{filename}:@var{linenum}
+Set a breakpoint at line @var{linenum} in source file @var{filename}.
-The debugger could not parse a type specification output by the compiler
-for some C++ object.
+@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.
-@end table
+@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.
-@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.
+@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}). In any selected frame but the innermost, this will
+cause the 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} doesn't 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.
-@samp{core-file} with no argument specifies that no core file is
-to be used.
+_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.
-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}).
+@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}, for more
+information on breakpoint conditions.
-@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.
+@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 the first time it
+is hit. @xref{Disabling}.
-@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.
+@item rbreak @var{regex}
+@kindex rbreak
+@cindex regular expression
+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{$_} and @code{info breakpoints}
+@item info breakpoints @r{[}@var{n}@r{]}
+@item info break @r{[}@var{n}@r{]}
+Print a list of all breakpoints (but not watchpoints) set and not
+deleted, showing their numbers, where in the program they are, and any
+special features in use for them. Disabled breakpoints are included in
+the list, but marked as disabled. @code{info break} with a breakpoint
+number @var{n} as argument lists only that breakpoint. The convenience
+variable @code{$_} and the default examining-address for the @code{x}
+command are set to the address of the last breakpoint listed
+(@pxref{Memory}). The equivalent command for watchpoints is @code{info
+watch}. @end table
-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.
+_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 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 Set Watchpoints, Exception Handling, Set Breaks, Breakpoints
+@subsection Setting Watchpoints
+@cindex setting watchpoints
+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.
-Beware: the similar command @samp{info targets} lists all possible
-targets rather than current ones.
+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.
-@end table
+@table @code
+@kindex watch
+@item watch @var{expr}
+Set a watchpoint for an expression.
-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.
+@kindex info watchpoints
+@item info watchpoints
+This command prints a list of watchpoints; it is otherwise similar to
+@code{info break}.
+@end table
-@kindex sharedlibrary
-@kindex share
-@cindex shared libraries
+@node Exception Handling, Delete Breaks, Set Watchpoints, Breakpoints
+@subsection Breakpoints and Exceptions
+@cindex exception handlers
-_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:
+Some languages, such as GNU C++, implement exception handling. You can
+use _GDBN__ 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.
@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 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
+You can use @code{info catch} to list active exception handlers;
+@pxref{Frame Info}.
-@node Compilation, Targets, Files, Top
-@chapter Compiling for Debugging
+There are currently some limitations to exception handling in _GDBN__.
+These will be corrected in a future release.
-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.
+@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 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
-To request debugging information, specify the @samp{-g} option when you run
-the compiler.
+@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's 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:
-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.
+@example
+ /* @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
-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.
+@noindent
+To make the debugger catch all exceptions before any stack
+unwinding takes place, set a breakpoint on @code{__raise_exception}
+(@pxref{Breakpoints}).
-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}).
+With a conditional breakpoint (@xref{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 the
+program when any of a number of exceptions are raised.
-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 Delete Breaks, Disabling, Exception Handling, Breakpoints
+@subsection Deleting 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.
+@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 the program to stop there. This
+is called @dfn{deleting} the breakpoint. A breakpoint that has been
+deleted no longer exists; it is forgotten.
-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
+With the @code{clear} command you can delete breakpoints according to
+where they are in the program. With the @code{delete} command you can
+delete individual breakpoints or watchpoints by specifying their
+breakpoint numbers.
-@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.
+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.
-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 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.
-@menu
-* Active Targets:: Active Targets
-* Target Commands:: Commands for Managing Targets
-@end menu
+@item clear @var{function}
+@itemx clear @var{filename}:@var{function}
+Delete any breakpoints set at entry to the function @var{function}.
-@node Active Targets, Target Commands, Targets, Targets
-@section Active Targets
-@cindex stacking targets
-@cindex active targets
-@cindex multiple targets
+@item clear @var{linenum}
+@itemx clear @var{filename}:@var{linenum}
+Delete any breakpoints set at or within the code of the specified line.
+
+@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've @code{set confirm off}). You
+can abbreviate this command as @code{d}.
+@end table
+
+@node Disabling, Conditions, Delete Breaks, Breakpoints
+@subsection Disabling Breakpoints
+
+@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.
+
+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
+don't know which numbers to use.
+
+A breakpoint or watchpoint can have any of four different states of
+enablement:
+
+@itemize @bullet
+@item
+Enabled. The breakpoint will stop the program. A breakpoint set
+with the @code{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 set
+with the @code{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
+
+You can use the following commands to enable or disable breakpoints and
+watchpoints:
+
+@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}.
+
+@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 the program.
+
+@item enable @r{[}breakpoints@r{]} once @var{bnums}@dots{}
+Enable the specified breakpoints temporarily. Each will be disabled
+again the next time it stops the program.
+
+@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 the program.
+@end table
+
+Save for a breakpoint set with @code{tbreak} (@pxref{Set Breaks}),
+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;
+@pxref{Continuing and Stepping}.)
+
+@node Conditions, Break Commands, Disabling, Breakpoints
+@subsection Break Conditions
+@cindex conditional breakpoints
+@cindex breakpoint conditions
+
+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 @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.
+
+Break conditions ca 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 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}).
+
+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}.
+They can also be changed at any time with the @code{condition} command.
+The @code{watch} command doesn't recognize the @code{if} keyword;
+@code{condition} is the only way to impose a further condition on a
+watchpoint.
+
+@table @code
+@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
+the 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. _GDBN__ does
+not actually evaluate @var{expression} at the time the @code{condition}
+command is given, however. @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 c @var{count}
+@itemx fg @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.
+
+An argument to this command is meaningful only when the program stopped
+due to a breakpoint. At other times, the argument to @code{continue} is
+ignored.
+
+The synonym @code{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.
+
+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}.
+
+@node Break Commands, Breakpoint Menus, Conditions, Breakpoints
+@subsection Breakpoint Command Lists
+
+@cindex breakpoint commands
+You can give any breakpoint (or watchpoint) 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 @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.
+
+To remove all commands from a breakpoint, type @code{commands} followed
+immediately by @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
+
+Pressing @key{RET} as a means of repeating the last _GDBN__ command is
+disabled within a @var{command-list}.
+
+You can use breakpoint commands to start the 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.
+
+@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.
+
+The commands @code{echo} and @code{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 @code{x} is positive.
+
+_0__@example
+break foo if x>0
+commands
+silent
+echo x is\040
+output x
+echo \n
+cont
+end
+_1__@end example
+
+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 the program does not stop, and start with the @code{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
+
+@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.
+
+Under Unix, you can get around this problem by writing actions into
+the breakpoint condition rather than in 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 zero so the 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. _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:
+
+@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
+
+
+@node Error in Breakpoints, , Breakpoint Menus, Breakpoints
+@subsection ``Cannot Insert Breakpoints''
+
+@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 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.
+
+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 @code{exec-file} command to specify that _GDBN__
+should run the program under that name. Then start the program again.
+
+@c FIXME: RMS commented here "Show example". Maybe when someone
+@c explains the first FIXME: in this section...
+
+@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 and Stepping, Signals, Breakpoints, Stopping
+@section Continuing and Stepping
+
+@cindex stepping
+@cindex continuing
+@cindex resuming execution
+@dfn{Continuing} means resuming program execution until your program
+completes normally. In contrast, @dfn{stepping} means resuming program
+execution for a very limited time: one line of source code, or one
+machine instruction. Either when continuing or when stepping, the
+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; @pxref{Signals}.)
+
+@table @code
+@item continue @r{[}@var{ignore-count}@r{]}
+@kindex continue
+Resume program execution, at the address where the 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}).
+
+To resume execution at a different place, you can use @code{return}
+(@pxref{Returning}) to go back to the calling function; or @code{jump}
+(@pxref{Jumping}) to go to an arbitrary location in your program.
+
+@end table
+
+A typical technique for using stepping is to set a breakpoint
+(@pxref{Breakpoints}) at the beginning of the function or the section of
+the program in which a problem is believed to lie, run the 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.
+
+@table @code
+@item step
+@kindex step
+@kindex s
+Continue running the program until control reaches a different source
+line, then stop it and return control to _GDBN__. This command is
+abbreviated @code{s}.
+
+@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
+
+@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 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 finish
+@kindex finish
+Continue running until just after function in the selected stack frame
+returns. Print the returned value (if any).
+
+Contrast this with the @code{return} command (@pxref{Returning}).
+
+@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.
+
+This means that when you reach the end of a loop after single stepping
+though it, @code{until} will cause the 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.
+
+@code{until} always stops the program if it attempts to exit the current
+stack frame.
+
+@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
+(_GDBP__) f
+#0 main (argc=4, argv=0xf7fffae8) at m4.c:206
+206 expand_input();
+(_GDBP__) until
+195 for ( ; argc > 0; NEXTARG) @{
+@end example
+
+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.
+
+@code{until} with no argument works by means of single
+instruction stepping, and hence is slower than @code{until} with an
+argument.
+
+@item until @var{location}
+@item u @var{location}
+Continue running the 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}). This form of the command uses breakpoints, and hence is
+quicker than @code{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 @code{step}.
+
+@item nexti
+@itemx ni
+@kindex nexti
+@kindex ni
+Execute one machine instruction, but if it is a function call,
+proceed until the function returns.
+
+An argument is a repeat count, as in @code{next}.
+@end table
+
+
+@node Signals, , Continuing and Stepping, Stopping
+@section Signals
+@cindex signals
+
+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 the program has
+requested an alarm).
+
+@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 the interrupt: to kill the program.
+
+_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.
+
+@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 @code{handle} command.
+
+@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 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
+
+@c @group
+The keywords allowed by the @code{handle} command can be abbreviated.
+Their full names are:
+
+@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.
+
+@item stop
+_GDBN__ should stop the program when this signal happens. This implies
+the @code{print} keyword as well.
+
+@item print
+_GDBN__ should print a message when this signal happens.
+
+@item noprint
+_GDBN__ should not mention the occurrence of the signal at all. This
+implies the @code{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.
+
+@item nopass
+_GDBN__ should not allow the program to see this signal.
+@end table
+@c @end group
+
+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 @code{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 @code{handle} command with
+@code{pass} or @code{nopass} to control whether that signal will be seen by
+the program when you later continue it.
+
+You can also use the @code{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. 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}.
+
+@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.
+
+@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
+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 @code{frame} command does
+(@pxref{Frame Info, Info}).
+
+@menu
+* Frames:: Stack Frames
+* Backtrace:: Backtraces
+* Selection:: Selecting a Frame
+* Frame Info:: Information on a Frame
+@end menu
+
+@node Frames, Backtrace, Stack, Stack
+@section Stack Frames
+
+@cindex frame
+@cindex stack frame
+The call stack is divided up into contiguous pieces called @dfn{stack
+frames}, or @dfn{frames} for short; each frame is the data associated
+with one call to one function. The frame contains the arguments given
+to the function, the function's local variables, and the address at
+which the function is executing.
+
+@cindex initial frame
+@cindex outermost frame
+@cindex innermost frame
+When your program is started, the stack has only one frame, that of the
+function @code{main}. This is called the @dfn{initial} frame or the
+@dfn{outermost} frame. Each time a function is called, a new frame is
+made. Each time a function returns, the frame for that function invocation
+is eliminated. If a function is recursive, there can be many frames for
+the same function. The frame for the function in which execution is
+actually occurring is called the @dfn{innermost} frame. This is the most
+recently created of all the stack frames that still exist.
+
+@cindex frame pointer
+Inside your program, stack frames are identified by their addresses. A
+stack frame consists of many bytes, each of which has its own address; each
+kind of computer has a convention for choosing one of those bytes whose
+address serves as the address of the frame. Usually this address is kept
+in a register called the @dfn{frame pointer register} while execution is
+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 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 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 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
+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.
+
+@table @code
+@item backtrace
+@itemx bt
+@kindex backtrace
+@kindex bt
+Print a backtrace of the entire stack: one line per frame for all
+frames in the stack.
+
+You can stop the backtrace at any time by typing the system interrupt
+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}
+Similar, but print only the outermost @var{n} frames.
+@end table
+
+@kindex where
+@kindex info stack
+@kindex info s
+The names @code{where} and @code{info stack} (abbreviated @code{info s})
+are additional aliases for @code{backtrace}.
+
+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.
+
+@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 group
+@end smallexample
+
+@noindent
+The display for frame zero doesn't begin with a program counter
+value, indicating that the 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
+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
+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
+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
+@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 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:
+
+@smallexample
+(_GDBP__) up
+#1 0x22f0 in main (argc=1, argv=0xf7fffbf4, env=0xf7fffbfc) at env.c:10
+10 read_input_file (argv[i]);
+@end smallexample
+
+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}.
+
+@table @code
+@item up-silently @var{n}
+@itemx down-silently @var{n}
+@kindex down-silently
+@kindex up-silently
+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.
+
+@end table
+
+@node Frame Info, , Selection, Stack
+@section Information About a Frame
+
+There are several other commands to print information about the selected
+stack frame.
+
+@table @code
+@item frame
+@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}).
+
+@item info frame
+@kindex info frame
+@itemx info f
+@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 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
+something has gone wrong that has made the stack format fail to fit
+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.
+
+@item info args
+@kindex info args
+Print the arguments of the selected frame, each on a separate line.
+
+@item info locals
+@kindex info locals
+Print the local variables of the selected frame, each on a separate
+line. These are all variables declared static or automatic within all
+program blocks that execution in this frame is currently inside of.
+
+@item info catch
+@kindex info catch
+@cindex catch exceptions
+@cindex exception handlers
+Print a list of all the exception handlers that are active in the
+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}.
+@end table
+
+@node Source, Data, Stack, Top
+@chapter Examining Source Files
+
+_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 built it. When your program stops, _GDBN__ spontaneously
+prints the line where it stopped. Likewise, when you select a stack
+frame (@pxref{Selection}), _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}.
+
+@menu
+* 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
+@section Printing Source Lines
+
+@kindex list
+@kindex l
+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 @code{list} command most commonly used:
+
+@table @code
+@item list @var{linenum}
+Print lines centered around line number @var{linenum} in the
+current source file.
+
+@item list @var{function}
+Print lines centered around the beginning of function
+@var{function}.
+
+@item list
+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
+lines centered around that line.
+
+@item list -
+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 @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 source file.
+
+@cindex linespec
+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 @code{list}:
+
+@table @code
+@item list @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 lines ending with @var{last}.
+
+@item list @var{first},
+Print lines starting with @var{first}.
+
+@item list +
+Print lines just after the lines last printed.
+
+@item list -
+Print lines just before the lines last printed.
+
+@item list
+As described in the preceding table.
+@end table
+
+Here are the ways of specifying a single source line---all the
+kinds of linespec.
+
+@table @code
+@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 @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{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}. 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
+
+@node Search, Source Path, List, Source
+@section Searching Source Files
+@cindex searching
+@kindex reverse-search
+
+There are two commands for searching through the current source file for a
+regular expression.
+
+@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 abbreviate the command name
+as @code{fo}. The synonym @samp{search @var{regexp}} is also supported.
+
+@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 as @code{rev}.
+@end table
+
+@node Source Path, Machine Code, Search, Source
+@section Specifying Source Directories
+
+@cindex source path
+@cindex directories for source files
+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__ 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 executable search path is @emph{not} used for this purpose. Neither is
+the current working directory, unless it happens to be in the source
+path.
+
+If _GDBN__ can't 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
+each line is in the file, etc.
+
+@kindex directory
+When you start _GDBN__, its source path is empty.
+To add other directories, use the @code{directory} command.
+
+@table @code
+@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 @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.
+
+@c RET-repeat for @code{directory} is explicitly disabled, but since
+@c repeating it would be a no-op we don't say that. (thanks to RMS)
+
+@item show directories
+@kindex show directories
+Print the source path: show which directories it contains.
+@end table
+
+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 @code{directory} with no argument to reset the source path to empty.
+
+@item
+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 Machine Code, , Source Path, Source
+@section Source and Machine Code
+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.
+
+@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}).
+@end table
+
+For example, we can use @code{info line} to inquire on where the object
+code for the first line of function @code{m4_changequote} lies:
+@smallexample
+(_GDBP__) info line m4_changecom
+Line 895 of "builtin.c" starts at pc 0x634c and ends at 0x6350.
+@end smallexample
-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.
+@noindent
+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
-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.
+@cindex @code{$_} and @code{info line}
+After @code{info line}, the default address for the @code{x}
+command is changed to the starting address of the line, so that
+@samp{x/i} is sufficient to begin examining the machine code
+(@pxref{Memory}). Also, this address is saved as the value of the
+convenience variable @code{$_} (@pxref{Convenience Vars}).
-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.
+@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.
+@end table
-When you specify a new target in a given stratum, it replaces any target
-previously in that stratum.
+We can use @code{disassemble} to inspect the object code
+range shown in the last @code{info line} example:
-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}.
+@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.
+(_GDBP__)
-@node Target Commands, , Active Targets, Targets
-@section Commands for Managing Targets
+@end smallexample
+
+@node Data, Languages, Source, Top
+@chapter Examining Data
+
+@cindex printing data
+@cindex examining data
+@kindex print
+@kindex inspect
+@c "inspect" isn't quite a synonym if you're using Epoch, which we don't
+@c document because it's 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}). You type
+
+@example
+print @var{exp}
+@end example
+
+@noindent
+where @var{exp} is an expression (in the source language), and
+the value of @var{exp} is printed in a format appropriate to its data
+type.
+
+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}.
+
+If you're 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}.
+
+@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
+@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 these operators in addition to those of programming
+languages:
@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 @@
+@samp{@@} is a binary operator for treating parts of memory as arrays.
+@xref{Arrays}, for more information.
+
+@item ::
+@samp{::} allows you to specify a variable in terms of the file or
+function where it is defined. @xref{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 binary operators, just as in
+a cast). This construct is allowed regardless of what kind of data is
+normally supposed to reside at @var{addr}.@refill
+@end table
+
+@node Variables, Arrays, Expressions, Data
+@section Program Variables
+
+The most common kind of expression to use is the name of a variable
+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
+
+@example
+foo (a)
+ int a;
+@{
+ bar (a);
+ @{
+ int b = test ();
+ bar (b);
+ @}
+@}
+@end example
+
+@noindent
+the variable @code{a} is usable whenever the 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}
+is declared.
+
+@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 (in different source files). If that happens,
+referring to that name has unpredictable effects. If you wish, you can
+specify a variable in a particular file, using the colon-colon notation:
+
+@cindex colon-colon
+@kindex ::
+@example
+@var{file}::@var{variable}
+@end example
+
+@noindent
+Here @var{file} is the name of the source file whose variable you want.
+
+@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 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're
+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're 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, Output formats, Variables, Data
+@section Artificial Arrays
+
+@cindex artificial array
+@kindex @@
+It is often useful to print out several successive objects of the
+same type in memory; a section of an array, or an array of
+dynamically determined size for which only a pointer exists in the
+program.
+
+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 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
+first element, and so on. Here is an example. If a program says
-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}
+int *array = (int *) malloc (len * sizeof (int));
@end example
@noindent
-(without any parameters) will issue a message about what
-parameters are required for that target type.
-
-@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}).
+you can print the contents of @code{array} with
+
+@example
+p *array@@len
+@end example
+
+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.
+Artificial arrays most often appear in expressions via the value history
+(@pxref{Value History}), after printing one out.)
+
+Sometimes the artificial array mechanism isn't quite enough; in
+moderately complex data structures, the elements of interest may not
+actually be adjacent---for example, if you're 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}) 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're interested in the
+values of a field @code{fv} in each structure. Here's an example of
+what you might type:
+@example
+set $i = 0
+p dtab[$i++]->fv
+@key{RET}
+@key{RET}
+@dots{}
+@end example
+
+@node Output formats, Memory, Arrays, Data
+@section Output formats
+
+@cindex formatted output
+@cindex output formats
+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 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
+@code{print} command with a slash and a format letter. The format
+letters supported are:
+
+@table @code
+@item x
+Regard the bits of the value as an integer, and print the integer in
+hexadecimal.
+
+@item d
+Print as integer in signed decimal.
+
+@item u
+Print as integer in unsigned decimal.
+
+@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
+_0__$3 = 0x54320 <_initialize_vx+396>_1__
+@end example
+
+
+@item c
+Regard as an integer and print it as a character constant.
+
+@item f
+Regard the bits of the value as a floating point number and print
+using typical floating point syntax.
@end table
-Here are some common targets (available, or not, depending on _GDBN__
-configuration):
+For example, to print the program counter in hex (@pxref{Registers}), type
+
+@example
+p/x $pc
+@end example
+
+@noindent
+Note that no space is required before the slash; this is because command
+names in _GDBN__ cannot contain a slash.
+
+To reprint the last value in the value history with a different format,
+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.
+
+@node Memory, Auto Display, Output formats, Data
+@section Examining Memory
+@cindex examining memory
@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 x
+@item x/@var{nfu} @var{expr}
+The command @code{x} (for `examine') can be used to examine memory
+without being constrained by your program's data types. You can specify
+the unit size @var{u} of memory to inspect, and a repeat count @var{n} of how
+many of those units to display. @code{x} understands the formats
+@var{f} used by @code{print}; two additional formats, @samp{s} (string)
+and @samp{i} (machine instruction) can be used without specifying a unit
+size.
+@end table
-@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}}.
+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}).
-@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}).
+Since the letters indicating unit sizes are all distinct from the
+letters specifying output formats, you don't 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.
-_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}.
+After the format specification, you supply an expression for the address
+where _GDBN__ is to begin reading from 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} for more
+information on expressions.
-_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}.
+These are the memory units @var{u} you can specify with the @code{x}
+command:
-_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.
+@table @code
+@item b
+Examine individual bytes.
+
+@item h
+Examine halfwords (two bytes each).
+
+@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.
-_fi__(_VXWORKS__)
+@item g
+Examine giant words (8 bytes).
@end table
-_if__(_GENERIC__)
-Different targets are available on different configurations of _GDBN__; your
-configuration may have more or fewer targets.
-_fi__(_GENERIC__)
+You can combine these unit specifications with any of the formats
+described for @code{print}. @xref{Output formats}.
-@node Running, Stopping, Targets, Top
-@chapter Running Programs Under _GDBN__
+@code{x} has two additional output specifications which derive the unit
+size from the data inspected:
-@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}).
+@table @code
+@item s
+Print a null-terminated string of characters. Any explicitly specified
+unit size is ignored; instead, the unit is however many bytes it takes
+to reach a null character (including the null character).
-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.
+@item i
+Print a machine instruction in assembler syntax (or nearly). Any
+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 @code{disassemble} gives an alternative way of
+inspecting machine instructions. @xref{Machine Code}.
+@end table
-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:
+If you omit either the format @var{f} or the unit size @var{u}, @code{x}
+will use the same one that was used last. If you don't use any letters
+or digits after the slash, you can omit the slash as well.
-@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.
+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.
-@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
+When the @code{print} command shows a value that resides in memory,
+@code{print} also sets the default address for the @code{x} command.
+@code{info line} also sets the default for @code{x}, to the address of
+the start of the machine code for the specified line (@pxref{Machine
+Code}), and @code{info breakpoints} sets it to the address of the last
+breakpoint listed (@pxref{Set Breaks}).
-@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 use @key{RET} to repeat an @code{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.
-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.
+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). Omitting the repeat count @var{n} displays one unit of the
+appropriate size. The repeat count must be a decimal integer. It has
+the same effect as repeating the @code{x} command @var{n} times except
+that the output may be more compact, with several units per line. For
+example,
-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}.
+@example
+x/10i $pc
+@end example
-If the modification time of your symbol file has changed since the last
-time _GDBN__ read its symbols, _GDBN__ will discard its symbol table and re-read
-it. In this process, it tries to retain your current breakpoints.
+@noindent
+prints ten instructions starting with the one to be executed next in the
+selected frame. After doing this, you could print a further seven
+instructions with
-@menu
-* Arguments:: Specifying the arguments for your program.
-* Environment:: Specifying the environment for your program.
-* Working Directory:: Specifying the working directory for giving
- to your program when it is run.
-* Input/Output:: Specifying the program's standard input and output.
-* Attach:: Debugging a process started outside _GDBN__.
-* Kill Process:: Getting rid of the child process running your program.
-@end menu
+@example
+x/7
+@end example
-@node Arguments, Environment, Running, Running
-@section Your Program's Arguments
+@noindent
+---where the format and address are allowed to default.
+
+@cindex @code{$_}, @code{$__}, and value history
+The addresses and contents printed by the @code{x} command are not put
+in the value history because there is often too much of them and they
+would get in the way. Instead, _GDBN__ makes these values available for
+subsequent use in expressions as values of the convenience variables
+@code{$_} and @code{$__}. After an @code{x} command, the last address
+examined is available for use in expressions in the convenience variable
+@code{$_}. 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.
-@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.
+@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.
+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:
+
+@example
+2: foo = 38
+3: bar[5] = (struct hack *) 0x3804
+@end example
-@samp{run} with no arguments uses the same arguments used by the previous
-@samp{run}.
+@noindent
+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}.
-@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.
+@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}.
-@item show args
-@kindex show args
-Show the arguments to give your program when it is started.
-@end table
+@code{display} will not repeat if you press @key{RET} again after using it.
-@node Environment, Working Directory, Arguments, Running
-@section Your Program's Environment
+@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}.
-@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.
+@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}.
+@end table
-@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.
+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}).
-@item show environment
-Print the names and values of all environment variables to be given to
-your program when it is started.
+@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.
-@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.
+@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{}}.)
-For example, this command:
+@item disable display @var{dnums}@dots{}
+@kindex disable display
+Disable the display of item numbers @var{dnums}. A disabled display
+item is not printed automatically, but is not forgotten. It may be
+enabled again later.
-@example
-set env USER = foo
-@end example
+@item enable display @var{dnums}@dots{}
+@kindex enable display
+Enable display of item numbers @var{dnums}. It becomes effective once
+again in auto display of its expression, until you specify otherwise.
-@noindent
-tells the program, when subsequently run, to assume it is being run
-on behalf of the user named @samp{foo}.
+@item display
+Display the current values of the expressions on the list, just as is
+done when the program stops.
-@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}.
+@item info display
+@kindex info display
+Print the list of expressions previously set up to display
+automatically, each one with its item number, but without showing the
+values. This includes disabled expressions, which are marked as such.
+It also includes expressions which would not be displayed right now
+because they refer to automatic variables not currently available.
@end table
-@node Working Directory, Input/Output, Environment, Running
-@section Your Program's Working Directory
+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 the 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 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.
+@node Print Settings, Value History, Auto Display, Data
+@section Print Settings
-The _GDBN__ working directory also serves as a default for the commands
-that specify files for _GDBN__ to operate on. @xref{Files}.
+@cindex format options
+@cindex print settings
+_GDBN__ provides the following ways to control how arrays, structures,
+and symbols are printed.
+
+@noindent
+These settings are useful for debugging programs in any language:
@table @code
-@item cd @var{directory}
-@kindex cd
-Set _GDBN__'s working directory to @var{directory}.
+@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}:
+@smallexample
+(_GDBP__) f
+#0 set_quotes (lq=0x34c78 "<<", rq=0x34c88 ">>")
+ at input.c:530
+530 if (lquote != def_lquote)
+@end smallexample
-@item pwd
-@kindex pwd
-Print _GDBN__'s working directory.
-@end table
+@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
+(_GDBP__) set print addr off
+(_GDBP__) f
+#0 set_quotes (lq="<<", rq=">>") at input.c:530
+530 if (lquote != def_lquote)
+@end example
-@node Input/Output, Attach, Working Directory, Running
-@section Your Program's Input and Output
+@item show print address
+@kindex show print address
+Show whether or not addresses are to be printed.
-@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 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.
-You can redirect the program's input and/or output using @samp{sh}-style
-redirection commands in the @samp{run} command. For example,
+@item set print array off.
+Return to compressed format for arrays.
-@example
-run > outfile
-@end example
+@item show print array
+@kindex show print array
+Show whether compressed or pretty format is selected for displaying
+arrays.
-@noindent
-starts the program, diverting its output to the file @file{outfile}.
+@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.
-@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,
+@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
-tty /dev/ttyb
+$1 = @{
+ next = 0x0,
+ flags = @{
+ sweet = 1,
+ sour = 1
+ @},
+ meat = 0x54 "Pork"
+@}
@end example
-@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.
-
-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.
+@item set print pretty off
+Cause _GDBN__ to print structures in a compact format, like this:
-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.
+@smallexample
+$1 = @{next = 0x0, flags = @{sweet = 1, sour = 1@}, meat \
+= 0x54 "Pork"@}
+@end smallexample
-@node Attach, Kill Process, Input/Output, Running
-@section Debugging an Already-Running Process
-@kindex attach
-@cindex attach
+@noindent
+This is the default format.
-@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.
-@end table
+@item show print pretty
+@kindex show print pretty
+Show which format _GDBN__ will use to print structures.
-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.
+@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}.
-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.
+@item set print sevenbit-strings off
+Print using either seven-bit or eight-bit characters, as required. This
+is the default.
-@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}.
+@item show print sevenbit-strings
+@kindex show print sevenbit-strings
+Show whether or not _GDBN__ will print only seven-bit characters.
-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}).
+@item set print union on
+@kindex set print union
+Tell _GDBN__ to print unions which are contained in structures. This is the
+default setting.
-@node Kill Process, , Attach, Running
-@section Killing the Child Process
+@item set print union off
+Tell _GDBN__ not to print unions which are contained in structures.
-@table @code
-@item kill
-@kindex kill
-Kill the child process in which your program is running under _GDBN__.
-@end table
+@item show print union
+@kindex show print union
+Ask _GDBN__ whether or not it will print unions which are contained in
+structures.
-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.
+For example, given the declarations
-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.
+@smallexample
+typedef enum @{Tree, Bug@} Species;
+typedef enum @{Big_tree, Acorn, Seedling@} Tree_forms;
+typedef enum @{Caterpillar, Cocoon, Butterfly@} Bug_forms;
-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).
+struct thing @{
+ Species it;
+ union @{
+ Tree_forms tree;
+ Bug_forms bug;
+ @} form;
+@};
-@node Stopping, Stack, Running, Top
-@chapter Stopping and Continuing
+struct thing foo = @{Tree, @{Acorn@}@};
+@end smallexample
-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.
+@noindent
+with @code{set print union on} in effect @samp{p foo} would print
-@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
+@smallexample
+$1 = @{it = Tree, form = @{tree = Acorn, bug = Cocoon@}@}
+@end smallexample
-@node Signals, Breakpoints, Stopping, Stopping
-@section Signals
-@cindex signals
+@noindent
+and with @code{set print union off} in effect it would print
-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).
+@smallexample
+$1 = @{it = Tree, form = @{...@}@}
+@end smallexample
+@end table
-@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.
+@noindent
+These settings are of interest when debugging C++ programs:
-_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.
+@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.
-@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.
+@item show print demangle
+@kindex show print demangle
+Show whether C++ names will be printed in mangled or demangled form.
-@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 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 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
+@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.
-The keywords allowed by the @samp{handle} command can be abbreviated.
-Their full names are
+@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.
-@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.
+@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 stop
-_GDBN__ should stop the program when this signal happens. This implies
-the @samp{print} keyword as well.
+@item show print object
+@kindex show print object
+Show whether actual, or declared, object types will be displayed.
-@item print
-_GDBN__ should print a message when this signal happens.
+@item set print vtbl
+@itemx set print vtbl on
+@kindex set print vtbl
+Pretty print C++ virtual function tables. The default is off.
-@item noprint
-_GDBN__ should not mention the occurrence of the signal at all. This
-implies the @samp{nostop} keyword as well.
+@item set print vtbl off
+Do not pretty print C++ virtual function tables.
-@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.
+@item show print vtbl
+@kindex show print vtbl
+Show whether C++ virtual function tables are pretty printed, or not.
-@item nopass
-_GDBN__ should not allow the program to see this signal.
@end table
-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.
-
-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}.
+@node Value History, Convenience Vars, Print Settings, Data
+@section Value History
-@node Breakpoints, Continuing, Signals, Stopping
-@section Breakpoints
+@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 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.
+@cindex @code{$}
+@cindex @code{$$}
+@cindex history number
+The values printed are given @dfn{history numbers} for you to refer to them
+by. These are successive integers starting with one. @code{print} shows you
+the history number assigned to a value by printing @samp{$@var{num} = }
+before the value; here @var{num} is the history number.
-@table @code
-@kindex info break
-@kindex $_
-@item info break
-The command @samp{info break} prints a list of all breakpoints set and not
-deleted, showing their numbers, where in the program they are, and any
-special features in use for them. Disabled breakpoints are included in the
-list, but marked as disabled. @samp{info break} with a breakpoint number
-as argument lists only that breakpoint. The convenience variable @code{$_}
-and the default examining-address for the @samp{x} command are set to the
-address of the last breakpoint listed (@pxref{Memory}).
+To refer to any previous value, use @samp{$} followed by the value's
+history number. The way @code{print} labels its output is designed to
+remind you of this. Just @code{$} refers to the most recent value in
+the history, and @code{$$} 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{$}.
-@kindex info watch
-@item info watch
-This command prints a list of watchpoints.
+For example, suppose you have just printed a pointer to a structure and
+want to see the contents of the structure. It suffices to type
-@cindex watchpoints
-A @dfn{watchpoint} is a special breakpoint that stops your program when
-the value of an expression changes. You can use a watchpoint to stop
-execution whenever the value of an expression changes, without having to
-predict a particular place in the inferior process where this may
-happen. Aside from the different syntax in setting a watchpoint, it is
-managed exactly like any other breakpoint and is enabled, disabled, and
-deleted using exactly the same commands.
+@example
+p *$
+@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.
+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:
-@end table
+@example
+p *$.next
+@end example
-@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
+@noindent
+You can print successive links in the chain by repeating this
+command---which you can do by just typing @key{RET}.
-@node Set Breaks, Exception Handling, Breakpoints, Breakpoints
-@subsection Setting Breakpoints
+Note that the history records values, not expressions. If the value of
+@code{x} is 4 and you type these commands:
-@kindex break
-@kindex watch
-Breakpoints are set with the @samp{break} command (abbreviated @samp{b}).
-Watchpoints are set with the @samp{watch} command.
+@example
+print x
+set x=5
+@end example
-You have several ways to say where the breakpoint should go.
+@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
-@item break @var{function}
-Set a breakpoint at entry to function @var{function}.
+@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 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.
+@item show values @var{n}
+Print ten history values centered on history item number @var{n}.
-@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.
+@item show values +
+Print ten history values just after the values last printed. If no more
+values are available, produces no display.
+@end table
-@item break @var{filename}:@var{linenum}
-Set a breakpoint at line @var{linenum} in source file @var{filename}.
+Pressing @key{RET} to repeat @code{show values @var{n}} has exactly the
+same effect as @samp{show values +}.
-@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.
+@node Convenience Vars, Registers, Value History, Data
+@section Convenience Variables
-@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.
+@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 direct effect on further execution
+of your program. That's 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}.)
-@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.
+You can save a value in a convenience variable with an assignment
+expression, just as you would set a variable in your program. Example:
-_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.
+@example
+set $foo = *object_ptr
+@end example
-@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.
+@noindent
+would save in @code{$foo} the value contained in the object pointed to by
+@code{object_ptr}.
-@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}.
+Using a convenience variable for the first time creates it; but its value
+is @code{void} until you assign a new value. You can alter the value with
+another assignment at any time.
-@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.
+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, when used as an expression, has the type of its current value.
-@kindex watch
-@item watch @var{expr}
-Set a watchpoint for an expression.
+@table @code
+@item show convenience
+@kindex show convenience
+Print a list of convenience variables used so far, and their values.
+Abbreviated @code{show con}.
@end table
-_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}).
+One of the ways to use a convenience variable is as a counter to be
+incremented or a pointer to be advanced. For example, to print
+a field from successive elements of an array of structures:
-@node Exception Handling, Delete Breaks, Set Breaks, Breakpoints
-@subsection Breakpoints and Exceptions
-@cindex exception handlers
+_0__@example
+set $i = 0
+print bar[$i++]->contents
+@i{@dots{} repeat that command by typing @key{RET}.}
+_1__@end example
-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.
+Some convenience variables are created automatically by _GDBN__ and given
+values likely to be useful.
-@cindex raise exceptions
-GNU C++ raises an exception by calling a library function named
-@code{__raise_exception} which has the following ANSI C interface:
+@table @code
+@item $_
+@kindex $_
+The variable @code{$_} is automatically set by the @code{x} command to
+the last address examined (@pxref{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{$__}.
-@example
- /* ADDR is where the exception identifier is stored.
- ID is the exception identifier. */
- void __raise_exception (void **addr, void *id);
-@end example
+@item $__
+@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
-@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.
+@node Registers, Floating Point Hardware, Convenience Vars, Data
+@section Registers
-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.
+@cindex registers
+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 @code{info registers} to see the names used on
+your machine.
@table @code
-@item catch @var{exceptions}
-@kindex catch
+@item info registers
+@kindex info registers
+Print the names and values of all registers except floating-point
+registers (in the selected stack frame).
-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 info all-registers
+@kindex info all-registers
+@cindex floating point registers
+Print the names and values of all registers, including floating-point
+registers.
-You can use @samp{info catch} to list active exception handlers;
-@pxref{Frame Info}.
+@item info registers @var{regname}
+Print the relativized value of register @var{regname}. @var{regname}
+may be any register name valid on the machine you are using, with
+or without the initial @samp{$}.
+@end table
-There are currently some limitations to exception handling in _GDBN__.
-These will be corrected in a future release.
+The register names @code{$pc} and @code{$sp} are used on most machines
+for the program counter register and the stack pointer. For example,
+you could print the program counter in hex with
+@example
+p/x $pc
+@end example
-@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
+@noindent
+or print the instruction to be executed next with
+@example
+x/i $pc
+@end example
-@node Delete Breaks, Disabling, Exception Handling, Breakpoints
-@subsection Deleting Breakpoints
+@noindent
+or add four to the stack pointer with
+@example
+set $sp += 4
+@end example
-@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.
+@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 @code{return};
+@pxref{Returning}.)
-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.
+Often @code{$fp} is used for a register that contains a pointer to the
+current stack frame, and @code{$ps} is sometimes 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 shows other 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}}).
-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.
+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.
-@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.
+Normally, 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 true contents of
+hardware registers, you must select the innermost frame (with
+@samp{frame 0}).
-@item clear @var{function}
-@itemx clear @var{filename}:@var{function}
-Delete any breakpoints set at entry to the function @var{function}.
+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.
-@item clear @var{linenum}
-@itemx clear @var{filename}:@var{linenum}
-Delete any breakpoints set at or within the code of the specified line.
+@node Floating Point Hardware, , Registers, Data
+@section Floating Point Hardware
+@cindex floating point
+Depending on the host machine architecture, _GDBN__ may be able to give
+you more information about the status of the floating point hardware.
-@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.
+@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 the program's
+native language, and allowing _GDBN__ to output values in a manner
+consistent with the syntax of the 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.
-@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.
+@menu
+* Setting:: Switching between source languages
+* Show:: Displaying the language
+* Checks:: Type and Range checks
+* Support:: Supported languages
+@end menu
-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.
+@node Setting, Show, Languages, Languages
+@section Switching between source languages
-A breakpoint can have any of four different states of enablement:
+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.
-@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
+@menu
+* Manually:: Setting the working language manually
+* Automatically:: Having _GDBN__ infer the source language
+@end menu
-You can use the following commands to enable or disable a breakpoint:
+@node Manually, Automatically, Setting, Setting
+@subsection Setting the working language
-@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.
+@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}.
-@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.
+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:
-@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).
+@example
+print a = b + c
+@end example
-@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).
+@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
-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).
+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.
-@node Conditions, Break Commands, Disabling, Breakpoints
-@subsection Break Conditions
-@cindex conditional breakpoints
-@cindex breakpoint conditions
+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.
-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}).
+@node Show, Checks, Setting, Languages
+@section Displaying the language
-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:
+The following commands will help you find out which language is the
+working language, and also what language source files were written in.
+@kindex show language
+@kindex info frame
+@kindex info source
@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.
+@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 the program.
-@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.
+@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.
-To make the breakpoint stop the next time it is reached, specify
-a count of zero.
+@item info source
+Among the other information listed here (@pxref{Symbols,,Examining the
+Symbol Table}) is the source language of this source file.
-@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.
+@end table
-This command is allowed only when the program stopped due to a
-breakpoint. At other times, the argument to @samp{cont} is ignored.
+@node Checks, Support, Show, Languages
+@section Type and range Checking
-The synonym @samp{fg} is provided purely for convenience, and has
-exactly the same behavior as other forms of the command.
-@end table
+@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 the 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
+the source language of the program being debugged.
+@xref{Support,,Supported Languages}, for the default settings
+of supported languages.
-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.
+@menu
+* Type Checking:: An overview of type checking
+* Range Checking:: An overview of range checking
+@end menu
-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}.
+@cindex type checking
+@cindex checks, type
+@node Type Checking, Range Checking, Checks, Checks
+@subsection An overview of type checking
-@node Break Commands, Error in Breakpoints, Conditions, Breakpoints
-@subsection Commands Executed on Breaking
+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,
-@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.
+@example
+1 + 2 @result{} 3
+@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 futher
+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 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.
+@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
-To remove all commands from a breakpoint, use the command
-@samp{commands} and follow it immediately by @samp{end}; that is, give
-no commands.
+@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
-With no arguments, @samp{commands} refers to the last breakpoint set
-(not to the breakpoint most recently encountered).
-@end table
+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.
-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.
+_GDBN__ provides some additional commands for controlling the range checker:
-@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.
+@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
-The commands @samp{echo} and @samp{output} that allow you to print precisely
-controlled output are often useful in silent breakpoints. @xref{Output}.
+@node Support, , Checks, Languages
+@section Supported Languages
-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.
+_GDBN__ _GDB_VN__ 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}) can be used with the constructs of
+any of the supported languages.
-@example
-break foo if x>0
-commands
-silent
-echo x is\040
-output x
-echo \n
-cont
-end
-@end example
+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.
-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:
+@menu
+* C:: C and C++
+* Modula-2:: Modula-2
+@end menu
-@example
-break 403
-commands
-silent
-set x = y + 4
-cont
-end
-@end example
+@node C, Modula-2, Support, Support
+@subsection C and C++
+@cindex C and C++
-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.
+@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.
-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
+@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++}.
-@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.
+@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
-@node Error in Breakpoints, , Break Commands, Breakpoints
-@subsection ``Cannot Insert Breakpoints''
+@cindex C and C++ operators
+@node C Operators, C Constants, C, C
+@subsubsection C and C++ Operators
-@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.
+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:
-When this happens, you have three ways to proceed:
+@itemize @bullet
+@item
+@emph{Integral types} include @code{int} with any of its storage-class
+specifiers, @code{char}, and @code{enum}s.
-@enumerate
@item
-Remove or disable the breakpoints, then continue.
+@emph{Floating-point types} include @code{float} and @code{double}.
@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.
+@emph{Pointer types} include all types defined as @code{(@var{type}
+*)}.
-@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
+@item
+@emph{Scalar types} include all of the above.
-@node Continuing, Stepping, Breakpoints, Stopping
-@section Continuing
+@end itemize
-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.
+@noindent
+The following operators are supported. They are listed here
+in order of increasing precedence:
@table @code
-@item continue
-@item cont
-@kindex cont
-@kindex continue
-Continue running the program at the place where it stopped.
-@end table
+_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.
-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.
+@item =
+Assignment. The value of an assignment expression is the value
+assigned. Defined on scalar types.
-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}.
+@item @var{op}=
+Used in an expression of the form @var{a} @var{op}@code{=} @var{b}, and
+translated to @var{a} @code{=} @var{a op b}. @var{op}@code{=} and
+@code{=} have the same precendence. @var{op} is any one of the
+operators @code{|}, @code{^}, @code{&}, @code{<<}, @code{>>}, @code{+},
+@code{-}, @code{*}, @code{/}, @code{%}.
-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}).
+@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.
-@node Stepping, , Continuing, Stopping
-@section Stepping
+@item ||
+Logical OR. Defined on integral types.
-@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.
+@item &&
+Logical AND. Defined on integral types.
-@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}.
+@item |
+Bitwise OR. Defined on integral types.
-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 ^
+Bitwise exclusive-OR. Defined on integral types.
-@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 &
+Bitwise AND. Defined on integral types.
-@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}.
+@item ==@r{, }!=
+Equality and inequality. Defined on scalar types. The value of these
+expressions is 0 for false and non-zero for true.
-An argument is a repeat count, as in @samp{step}.
+@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.
-@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 <<@r{, }>>
+left shift, and right shift. Defined on integral types.
-@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).
+@item @@
+The _GDBN__ ``artificial array'' operator (@pxref{Expressions}).
-Contrast this with the @samp{return} command (@pxref{Returning}).
+@item +@r{, }-
+Addition and subtraction. Defined on integral types, floating-point types and
+pointer types.
-@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.
+@item *@r{, }/@r{, }%
+Multiplication, division, and modulus. Multiplication and division are
+defined on integral and floating-point types. Modulus is defined on
+integral types.
-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.
+@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.
-@samp{until} always stops the program if it attempts to exit the current
-stack frame.
+@item *
+Pointer dereferencing. Defined on pointer types. Same precedence as
+@code{++}.
-@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 &
+Address operator. Defined on variables. Same precedence as @code{++}.
-@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 -
+Negative. Defined on integral and floating-point types. Same
+precedence as @code{++}.
-@item stepi
-@itemx si
-@kindex stepi
-@kindex si
-Execute one machine instruction, then stop and return to the debugger.
+@item !
+Logical negation. Defined on integral types. Same precedence as
+@code{++}.
-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}.
+@item ~
+Bitwise complement operator. Defined on integral types. Same precedence as
+@code{++}.
-An argument is a repeat count, as in @samp{step}.
+@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 nexti
-@itemx ni
-@kindex nexti
-@kindex ni
-Execute one machine instruction, but if it is a subroutine call,
-proceed until the subroutine returns.
+@item []
+Array indexing. @code{@var{a}[@var{i}]} is defined as
+@code{*(@var{a}+@var{i})}. Same precedence as @code{->}.
-An argument is a repeat count, as in @samp{next}.
+@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}). Same precedence as
+@code{::}, above. _1__
@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.
+@cindex C and C++ constants
+@node C Constants, Cplusplus expressions, C Operators, C
+@subsubsection C and C++ Constants
-The @samp{cont} command can be used after stepping to resume execution
-until the next breakpoint or signal.
+_GDBN__ allows you to express the constants of C and C++ in the
+following ways:
-@node Stack, Source, Stopping, Top
-@chapter Examining the Stack
+@itemize @bullet
-When your program has stopped, the first thing you need to know is where it
-stopped and how it got there.
+@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 an
+@samp{l}, specifying that the constant should be treated as a
+@code{long} value.
-@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}.
+@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
-When your program stops, the _GDBN__ commands for examining the stack allow you
-to see all of this information.
-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
-selected frame. There are special _GDBN__ commands to select whichever frame
-you are interested in.
+@node Cplusplus expressions, C Defaults, C Constants, C
+@subsubsection C++ Expressions
-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}).
+@cindex expressions in C++
+_GDBN__'s expression handling has the following extensions to
+interpret a significant subset of C++ expressions:
-@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
-@end menu
+@enumerate
-@node Frames, Backtrace, Stack, Stack
-@section Stack Frames
+@cindex member functions
+@item
+Member function calls are allowed; you can use expressions like
+@example
+count = aml->GetOriginal(x, y)
+@end example
-@cindex frame
-@cindex stack frame
-The call stack is divided up into contiguous pieces called @dfn{stack
-frames}, or @dfn{frames} for short; each frame is the data associated
-with one call to one function. The frame contains the arguments given
-to the function, the function's local variables, and the address at
-which the function is executing.
+@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.
-@cindex initial frame
-@cindex outermost frame
-@cindex innermost frame
-When your program is started, the stack has only one frame, that of the
-function @code{main}. This is called the @dfn{initial} frame or the
-@dfn{outermost} frame. Each time a function is called, a new frame is
-made. Each time a function returns, the frame for that function invocation
-is eliminated. If a function is recursive, there can be many frames for
-the same function. The frame for the function in which execution is
-actually occurring is called the @dfn{innermost} frame. This is the most
-recently created of all the stack frames that still exist.
+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've specified @samp{set print address off}.
-@cindex frame pointer
-Inside your program, stack frames are identified by their addresses. A
-stack frame consists of many bytes, each of which has its own address; each
-kind of computer has a convention for choosing one of those bytes whose
-address serves as the address of the frame. Usually this address is kept
-in a register called the @dfn{frame pointer register} while execution is
-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.
+@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}.
-@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.
+@end enumerate
-@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
-@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.
-@node Backtrace, Selection, Frames, Stack
-@section Backtraces
+@node C Defaults, C Checks, Cplusplus expressions, C
+@subsubsection C and C++ Defaults
+@cindex C and C++ defaults
-A backtrace is a summary of how the 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.
+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.
-@table @code
-@item backtrace
-@itemx bt
-@kindex backtrace
-@kindex bt
-Print a backtrace of the entire stack: one line per frame for all
-frames in the stack.
+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.
-You can stop the backtrace at any time by typing the system interrupt
-character, normally @kbd{Control-C}.
+@node C Checks, Debugging C, C Defaults, C
+@subsubsection C and C++ Type and Range Checks
+@cindex C and C++ checks
-@item backtrace @var{n}
-@itemx bt @var{n}
-Similar, but print only the innermost @var{n} frames.
+@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
-@item backtrace @var{-n}
-@itemx bt @var{-n}
-Similar, but print only the outermost @var{n} frames.
-@end table
+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:
-@kindex where
-@kindex info stack
-The names @samp{where} and @samp{info stack} are additional aliases
-for @samp{backtrace}.
+@itemize @bullet
+@item
+The two variables are structured and have the same structure, union, or
+enumerated tag.
-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}.
+@item
+Two two variables have the same type name, or types that have been
+declared equivalent through @code{typedef}.
-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.
+@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
-Here is an example of a backtrace. It was made with the command
-@samp{bt 3}, so it shows the innermost three frames.
+@end itemize
-@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 (...) (...)
-(More stack frames follow...)
-@end example
+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.
-@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.
+@node Debugging C, Debugging C plus plus, C Checks, C
+@subsubsection _GDBN__ and C
-@node Selection, Frame Info, Backtrace, Stack
-@section Selecting a Frame
+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{@{...@}}.
-Most commands for examining the stack and other data in the 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.
+The @code{@@} operator aids in the debugging of dynamic arrays, formed
+with pointers and a memory allocation function. (@pxref{Expressions})
+
+@node Debugging C plus plus, , Debugging C, C
+@subsubsection _GDBN__ Commands 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
-@item frame @var{n}
-@kindex frame
-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.
+@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}.
-@item frame @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
-switches between them.
+@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}.
-@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.
+@cindex C++ exception handling
+@item catch @var{exceptions}
+@itemx info catch
+Debug C++ exception handling using these commands. @xref{Exception Handling}.
+
+@cindex inheritance
+@item ptype @var{typename}
+Print inheritance relationships as well as other information for type
+@var{typename}.
+@xref{Symbols}.
+
+@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}.
+
+@item set print object
+@itemx show print object
+Choose whether to print derived (actual) or declared types of objects.
+@xref{Print Settings}.
+
+@item set print vtbl
+@itemx show print vtbl
+Control the format for printing virtual function tables.
+@xref{Print Settings}.
-@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.
@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:
-@example
-#3 main (argc=3, argv=??, env=??) at main.c:67
-67 read_input_file (argv[i]);
-@end example
+@node Modula-2, , C, Support
+@subsection Modula-2
+@cindex Modula-2
-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}.
+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.
-@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},
-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.
+@cindex expressions in Modula-2
+@menu
+* M2 Operators:: Built-in operators
+* Builtin 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
-@end table
+@node M2 Operators, Builtin Func/Proc, Modula-2, Modula-2
+@subsubsection Operators
+@cindex Modula-2 operators
-@node Frame Info, , Selection, Stack
-@section Information on a Frame
+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:
-There are several other commands to print information about the selected
-stack frame.
+@itemize @bullet
-@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.
+@item
+@emph{Integral types} consist of @code{INTEGER}, @code{CARDINAL}, and
+their subranges.
-@item info frame
-@kindex info frame
-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),
-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
-something has gone wrong that has made the stack format fail to fit
-the usual conventions.
+@item
+@emph{Character types} consist of @code{CHAR} and its subranges.
-@item info frame @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.
+@item
+@emph{Floating-point types} consist of @code{REAL}.
-@item info args
-@kindex info args
-Print the arguments of the selected frame, each on a separate line.
+@item
+@emph{Pointer types} consist of anything declared as @code{POINTER TO
+@var{type}}.
-@item info locals
-@kindex info locals
-Print the local variables of the selected frame, each on a separate
-line. These are all variables declared static or automatic within all
-program blocks that execution in this frame is currently inside of.
+@item
+@emph{Scalar types} consist of all of the above.
-@item info catch
-@kindex info catch
-@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}.
-@end table
+@item
+@emph{Set types} consist of @code{SET}s and @code{BITSET}s.
-@node Source, Data, Stack, Top
-@chapter Examining Source Files
+@item
+@emph{Boolean types} consist of @code{BOOLEAN}.
-_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.
+@end itemize
-@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.
-@end menu
+@noindent
+The following operators are supported, and appear in order of
+increasing precedence:
-@node List, Search, Source, Source
-@section Printing Source Lines
+@table @code
+_0__
+@item ,
+Function argument or array index separator.
-@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
-of the file you want to print.
+@item :=
+Assignment. The value of @var{var} @code{:=} @var{value} is
+@var{value}.
-Here are the forms of the @samp{list} command most commonly used:
+@item <@r{, }>
+Less than, greater than on integral, floating-point, or enumerated
+types.
-@table @code
-@item list @var{linenum}
-Print ten lines centered around line number @var{linenum} in the
-current source file.
+@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 list @var{function}
-Print ten lines centered around the beginning of function
-@var{function}.
+@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 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
-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.
+@item IN
+Set membership. Defined on set types and the types of their members.
+Same precedence as @code{<}.
-@item list -
-Print ten lines just before the lines last printed.
-@end table
+@item OR
+Boolean disjunction. Defined on boolean types.
-Repeating a @samp{list} command with @key{RET} discards the argument,
-so it is equivalent to typing just @samp{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.
+@item AND@r{, }&
+Boolean conjuction. Defined on boolean types.
-@cindex linespec
-In general, the @samp{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}:
+@item @@
+The _GDBN__ ``artificial array'' operator (@pxref{Expressions}).
-@table @code
-@item list @var{linespec}
-Print ten lines centered around the line specified by @var{linespec}.
+@item +@r{, }-
+Addition and subtraction on integral and floating-point types, or union
+and difference on set types.
-@item list @var{first},@var{last}
-Print lines from @var{first} to @var{last}. Both arguments are
-linespecs.
+@item *
+Multiplication on integral and floating-point types, or set intersection
+on set types.
-@item list ,@var{last}
-Print ten lines ending with @var{last}.
+@item /
+Division on floating-point types, or symmetric set difference on set
+types. Same precedence as @code{*}.
-@item list @var{first},
-Print ten lines starting with @var{first}.
+@item DIV@r{, }MOD
+Integer division and remainder. Defined on integral types. Same
+precedence as @code{*}.
-@item list +
-Print ten lines just after the lines last printed.
+@item -
+Negative. Defined on @code{INTEGER}s and @code{REAL}s.
-@item list -
-Print ten lines just before the lines last printed.
+@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.
-@item list
-As described in the preceding table.
@end table
-Here are the ways of specifying a single source line---all the
-kinds of linespec.
+@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__
-@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
-the same source file as the first linespec.
+@cindex Modula-2 builtins
+@node Builtin Func/Proc, M2 Constants, M2 Operators, Modula-2
+@subsubsection Built-in Functions and Procedures
-@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
-two, this specifies the line @var{offset} lines down from the
-first linespec.
+Modula-2 also makes available several built-in procedures and functions.
+In describing these, the following metavariables are used:
-@item -@var{offset}
-Specifies the line @var{offset} lines before the last line printed.
+@table @var
-@item @var{filename}:@var{linenum}
-Specifies line @var{linenum} in the source file @var{filename}.
+@item a
+represents an @code{ARRAY} variable.
-@item @var{function}
-Specifies the line of the open-brace that begins the body of the
-function @var{function}.
+@item c
+represents a @code{CHAR} constant or variable.
-@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.
+@item i
+represents a variable or constant of integral type.
-@item *@var{address}
-Specifies the line containing the program address @var{address}.
-@var{address} may be any expression.
-@end table
+@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}.
-One other command is used to map source lines to program addresses.
+@item n
+represents a variable or constant of integral or floating-point type.
-@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}.
+@item r
+represents a variable or constant of floating-point type.
-@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
+@item t
+represents a type.
-@node Search, Source Path, List, Source
-@section Searching Source Files
-@cindex searching
-@kindex search
-@kindex forward-search
-@kindex reverse-search
+@item v
+represents a variable.
-There are two commands for searching through the current source file for a
-regular expression.
+@item x
+represents a variable or constant of one of many types. See the
+explanation of the function for details.
-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.
+@end table
+
+All Modula-2 built-in procedures also return a result, described below.
-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}.
+@table @code
+@item ABS(@var{n})
+Returns the absolute value of @var{n}.
-@node Source Path, , Search, Source
-@section Specifying Source Directories
+@item CAP(@var{c})
+If @var{c} is a lower case letter, it returns its upper case
+equivalent, otherwise it returns its argument
-@cindex source path
-@cindex directories for source files
-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;
-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 executable search path is @emph{not} used for this purpose. Neither is
-the current working directory, unless it happens to be in the source
-path.
+@item CHR(@var{i})
+Returns the character whose ordinal value is @var{i}.
-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.
+@item DEC(@var{v})
+Decrements the value in the variable @var{v}. Returns the new value.
-Whenever you reset or rearrange the source path, _GDBN__ will clear out
-any information it has cached about where source files are found, where
-each line is in the file, etc.
+@item DEC(@var{v},@var{i})
+Decrements the value in the variable @var{v} by @var{i}. Returns the
+new value.
-@kindex directory
-When you start _GDBN__, its source path is empty.
-To add other directories, use the @samp{directory} command.
+@item EXCL(@var{m},@var{s})
+Removes the element @var{m} from the set @var{s}. Returns the new
+set.
-@table @code
-@item directory @var{dirnames...}
-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.
+@item FLOAT(@var{i})
+Returns the floating point equivalent of the integer @var{i}.
-@item directory
-Reset the source path to empty again. This requires confirmation.
+@item HIGH(@var{a})
+Returns the index of the last member of @var{a}.
-@item info directories
-@kindex info directories
-Print the source path: show which directories it contains.
-@end table
+@item INC(@var{v})
+Increments the value in the variable @var{v}. Returns the new value.
-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:
+@item INC(@var{v},@var{i})
+Increments the value in the variable @var{v} by @var{i}. Returns the
+new value.
-@enumerate
-@item
-Use @samp{directory} with no argument to reset the source path to empty.
+@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
-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.
-@end enumerate
+@item MAX(@var{t})
+Returns the maximum value of the type @var{t}.
-@node Data, Symbols, Source, Top
-@chapter Examining Data
+@item MIN(@var{t})
+Returns the minimum value of the type @var{t}.
-@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
+@item ODD(@var{i})
+Returns boolean TRUE if @var{i} is an odd number.
-@example
-print @var{exp}
-@end example
+@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.
-@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.
+@item SIZE(@var{x})
+Returns the size of its argument. @var{x} can be a variable or a type.
-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.
+@item TRUNC(@var{r})
+Returns the integral part of @var{r}.
-@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.
-@end menu
+@item VAL(@var{t},@var{i})
+Returns the member of the type @var{t} whose ordinal value is @var{i}.
+@end table
-@node Expressions, Variables, Data, Data
-@section Expressions
+@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 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.
+@cindex Modula-2 constants
+@node M2 Constants, M2 Defaults, Builtin Func/Proc, Modula-2
+@subsubsection Constants
-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.
+_GDBN__ allows you to express the constants of Modula-2 in the following
+ways:
-_GDBN__ supports three kinds of operator in addition to those of programming
-languages:
+@itemize @bullet
-@table @code
-@item @@
-@samp{@@} is a binary operator for treating parts of memory as arrays.
-@xref{Arrays}, for more information.
+@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 ::
-@samp{::} allows you to specify a variable in terms of the file or
-function it is defined in. @xref{Variables}.
+@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 @{@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
-a cast). This construct is allowed regardless of what kind of data is
-officially supposed to reside at @var{addr}.@refill
-@end table
+@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}.
-@node Variables, Arrays, Expressions, Data
-@section Program Variables
+@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}, for a
+brief explanation of escape sequences.
-The most common kind of expression to use is the name of a variable
-in your program.
+@item
+Enumerated constants consist of an enumerated identifier.
-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
+@item
+Boolean constants consist of the identifiers @code{TRUE} and
+@code{FALSE}.
-@example
-foo (a)
- int a;
-@{
- bar (a);
- @{
- int b = test ();
- bar (b);
- @}
-@}
-@end example
+@item
+Pointer constants consist of integral values only.
-@noindent
-the variable @code{a} is usable whenever the 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}
-is declared.
+@item
+Set constants are not yet supported.
-As a special 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:
+@end itemize
-@cindex colon-colon
-@cindex scope
-@kindex ::
-@example
-@var{block}::@var{variable}
-@end example
+@node M2 Defaults, Deviations, M2 Constants, Modula-2
+@subsubsection Modula-2 Defaults
+@cindex Modula-2 defaults
-@noindent
-Here @var{block} is the name of the source file whose variable you want.
+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.
-@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.
+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 Arrays, Format options, Variables, Data
-@section Artificial Arrays
+@node Deviations, M2 Checks, M2 Defaults, Modula-2
+@subsubsection Deviations from Standard Modula-2
+@cindex Modula-2, deviations from
-@cindex artificial array
-@kindex @@
-It is often useful to print out several successive objects of the
-same type in memory; a section of an array, or an array of
-dynamically determined size for which only a pointer exists in the
-program.
+A few changes have been made to make Modula-2 programs easier to debug.
+This is done primarily via loosening its type strictness:
-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
-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
-first element, and so on. Here is an example. If a program says
+@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.
-@example
-int *array = (int *) malloc (len * sizeof (int));
-@end example
+@item
+The assignment operator (@code{:=}) returns the value of its right-hand
+argument.
-@noindent
-you can print the contents of @code{array} with
+@item
+All builtin procedures both modify @emph{and} return their argument.
-@example
-p *array@@len
-@end example
+@end itemize
-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 M2 Checks, M2 Scope, Deviations, Modula-2
+@subsubsection Modula-2 Type and Range Checks
+@cindex Modula-2 checks
-@node Format options, Output formats, Arrays, Data
-@section Format options
+@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
-@cindex format options
-_GDBN__ provides a few ways to control how arrays, structures, and symbols are
-printed.
+_GDBN__ considers two Modula-2 variables type equivalent if:
-@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.
+@itemize @bullet
+@item
+They are of types that have been declared equivalent via a @code{TYPE
+@var{t1} = @var{t2}} statement
-@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
+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.)
-@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.
+@end itemize
-@item set arrayprint off.
-Return to compressed format for arrays.
+As long as type checking is enabled, any attempt to combine variables
+whose types are not equivalent is an error.
-@item show arrayprint
-@kindex show arrayprint
-Show whether compressed or pretty format is selected for displaying
-arrays.
+Range checking is done on all mathematical operations, assignment, array
+index bounds, and all builtin functions and procedures.
-@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.
+@node M2 Scope, GDB/M2, M2 Checks, Modula-2
+@subsubsection The scope operators @code{::} and @code{.}
+@cindex scope
+@kindex .
+@kindex ::
-@item show demangle
-@kindex show demangle
-Show whether C++ names will be printed in mangled or demangled form.
+There are a few subtle differences between the Modula-2 scope operator
+(@code{.}) and the _GDBN__ scope operator (@code{::}). The two have
+similar syntax:
-@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.
+@example
-@item show asm-demangle
-@kindex show asm-demangle
-Show whether C++ names in assembly listings will be printed in mangled
-or demangled form.
+@var{module} . @var{id}
+@var{scope} :: @var{id}
-@item set vtblprint
-@itemx set vtblprint on
-@kindex set vtblprint
-Pretty print C++ virtual function tables. The default is off.
+@end example
-@item set vtblprint off
-Do not pretty print C++ virtual function tables.
+@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 delcared
+identifier within the 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}), 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})
+
+_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
-@item show vtblprint
-@kindex show vtblprint
-Show whether C++ virtual function tables are pretty printed, or not.
+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 the program executes. _GDBN__ finds it in your
+program's symbol table, in the file indicated when you started _GDBN__
+(@pxref{File Options}), or by one of the file-management commands
+(@pxref{Files}).
-@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.
+@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 addressprint off
-Do not print addresses.
+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 addressprint
-@kindex show addressprint
-Show whether or not addresses are to be printed.
+@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}.
-@item set prettyprint on
-@kindex set prettyprint
-Cause _GDBN__ to print structures in an indented format with one member per
-line, like this:
+@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}}.@refill
+@item ptype @var{exp}
+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
-$1 = @{
- next = 0x0,
- flags = @{
- sweet = 1,
- sour = 1
- @},
- meat = 0x54 "Pork"
+struct complex @{double real; double imag;@} v;
+@end example
+@noindent
+compare the output of the two commands:
+@example
+(_GDBP__) whatis v
+type = struct complex
+(_GDBP__) ptype v
+type = struct complex @{
+ double real;
+ double imag;
@}
@end example
-@item set prettyprint off
-Cause _GDBN__ to print structures in a compact format, like this:
+@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.
-@smallexample
-$1 = @{next = 0x0, flags = @{sweet = 1, sour = 1@}, meat \
-= 0x54 "Pork"@}
-@end smallexample
+@item info sources
+@kindex info sources
+Print the names of all source files in the 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.
-@noindent
-This is the default format.
+@item info functions
+@kindex info functions
+Print the names and data types of all defined functions.
-@item show prettyprint
-@kindex show prettyprint
-Show which format _GDBN__ will use to print structures.
+@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}
+@kindex printsyms
+Write a dump of debugging symbol data into the file
+@var{filename}. Only symbols with debugging data are included. _GDBN__
+includes all the symbols it already knows about: that is, @var{filename}
+reflects symbols for only those files whose symbols _GDBN__ has read.
+You can find out which files these are using the command @code{info
+files}. The description of @code{symbol-file} describes how _GDBN__
+reads symbols; both commands are described under @ref{Files}.
+@end table
+
+@node Altering, _GDBN__ Files, Symbols, Top
+@chapter Altering Execution
-@item set unionprint on
-@kindex set unionprint
-Tell _GDBN__ to print unions which are contained in structures. This is the
-default setting.
+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.
-@item set unionprint off
-Tell _GDBN__ not to print unions which are contained in structures.
+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.
-@item show unionprint
-@kindex show unionprint
-Ask _GDBN__ whether or not it will print unions which are contained in
-structures.
+@menu
+* Assignment:: Assignment to Variables
+* Jumping:: Continuing at a Different Address
+* Signaling:: Giving the Program a Signal
+* Returning:: Returning from a Function
+* Calling:: Calling your Program's Functions
+* Patching:: Patching your Program
+@end menu
-For example, given the declarations
+@node Assignment, Jumping, Altering, Altering
+@section Assignment to Variables
-@smallexample
-typedef enum @{Tree, Bug@} Species;
-typedef enum @{Big_tree, Acorn, Seedling@} Tree_forms;
-typedef enum @{Caterpillar, Cocoon, Butterfly@} Bug_forms;
+@cindex assignment
+@cindex setting variables
+To alter the value of a variable, evaluate an assignment expression.
+@xref{Expressions}. For example,
-struct thing @{
- Species it;
- union @{
- Tree_forms tree;
- Bug_forms bug;
- @} form;
-@};
+@example
+print x=4
+@end example
-struct thing foo = @{Tree, @{Acorn@}@};
-@end smallexample
+@noindent
+would store the value 4 into the variable @code{x}, and then print the
+value of the assignment expression (which is 4). @xref{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}). 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} didn't 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
-with @samp{set unionprint on} in effect @samp{p foo} would print
+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
-@smallexample
-$1 = @{it = Tree, form = @{tree = Acorn, bug = Cocoon@}@}
-@end smallexample
+_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?
-@noindent
-and with @samp{set unionprint off} in effect it would print
+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} refers
+to memory location @code{0x83040} as an integer (which implies a certain size
+and representation in memory), and
@example
-$1 = @{it = Tree, form = @{...@}@}
+set @{int@}0x83040 = 4
@end example
-@end table
-@node Output formats, Auto Display, Format options, Data
-@section Output formats
+@noindent
+stores the value 4 into that memory location.
-@cindex formatted output
-@cindex output formats
-_GDBN__ normally prints all values according to their data types. 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}.
+@node Jumping, Signaling, Assignment, Altering
+@section Continuing at a Different Address
-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
-letters supported are:
+Ordinarily, when you continue the 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 @samp
-@item x
-Regard the bits of the value as an integer, and print the integer in
-hexadecimal.
+@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} for a
+description of the different forms of @var{linespec}.
-@item d
-Print as integer in signed decimal.
+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 the program.
-@item u
-Print as integer in unsigned decimal.
+@item jump *@var{address}
+Resume execution at the instruction at address @var{address}.
+@end table
-@item o
-Print as integer in octal.
+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,
-@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>
+set $pc = 0x485
@end example
+@noindent
+causes the next @code{continue} command or stepping command to execute at
+address 0x485, rather than at the address where the program stopped.
+@xref{Continuing and Stepping}.
-@item c
-Regard as an integer and print it as a character constant.
+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.
-@item f
-Regard the bits of the value as a floating point number and print
-using typical floating point syntax.
+@node Signaling, Returning, Jumping, Altering
+@c @group
+@section Giving the Program a Signal
+
+@table @code
+@item signal @var{signalnum}
+@kindex signal
+Resume execution where the 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 the 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
-For example, to print the program counter in hex (@pxref{Registers}), type
+@node Returning, Calling, Signaling, Altering
+@section Returning from a Function
-@example
-p/x $pc
-@end example
+@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
-@noindent
-Note that no space is required before the slash; this is because command
-names in _GDBN__ cannot contain a slash.
+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}.
-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
-expression. For example, @samp{p/x} reprints the last value in hex.
+This pops the selected stack frame (@pxref{Selection}), 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.
-@menu
-* Memory:: Examining Memory
-@end menu
+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}) resumes execution until the selected stack frame returns
+naturally.@refill
-@node Memory, , Output formats, Output formats
-@subsection Examining Memory
+@node Calling, Patching, Returning, Altering
+@section Calling your Program's Functions
-@cindex examining memory
+@cindex calling functions
+@kindex call
@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.
+@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've 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.
-@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.
@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.
+@node _GDBN__ Files, Targets, Altering, Top
+@chapter _GDBN__'s Files
-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:
+@menu
+* Files:: Commands to Specify Files
+* Symbol Errors:: Errors Reading Symbol Files
+@end menu
-These letters specify just the size of unit to examine:
+@node Files, Symbol Errors, _GDBN__ Files, _GDBN__ Files
+@section Commands to Specify Files
+@cindex core dump 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.
-@table @samp
-@item b
-Examine individual bytes.
+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}.
-@item h
-Examine halfwords (two bytes each).
+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 w
-Examine words (four bytes each).
+@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,
-@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.
+_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.
-@item g
-Examine giant words (8 bytes).
-@end table
+@code{file} with no argument makes _GDBN__ discard any information it
+has on both executable file and the symbol table.
-These letters specify just the way to print the contents:
+@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.
-@table @samp
-@item x
-Print as integers in unsigned hexadecimal.
+@item symbol-file @var{filename}
+@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.
-@item d
-Print as integers in signed decimal.
+@code{symbol-file} with no argument clears out _GDBN__'s information on your
+program's symbol table.
-@item u
-Print as integers in unsigned decimal.
+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__.
-@item o
-Print as integers in unsigned octal.
+@code{symbol-file} will not repeat if you press @key{RET} again after
+executing it once.
-@item a
-Print as an address, both absolute in hex and then relative
-to a symbol defined as an address below it.
+On some kinds of object files, the @code{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.
-@item c
-Print as character constants.
+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}).
-@item f
-Print as floating point. This works only with sizes @samp{w} and
-@samp{g}.
+When the symbol table is stored in COFF format, @code{symbol-file} does
+read the symbol table data in full right away. We haven't implemented
+the two-stage strategy for COFF yet.
-@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).
+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.
-@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.
-@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.
+
+@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 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 @code{kill} command
+(@pxref{Kill Process}).
-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.
+@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__)
-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.
+_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__)
-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.
+_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__)
-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.
+@code{load} will not repeat if you press @key{RET} again after using it.
-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,
+@item add-symbol-file @var{filename} @var{address}
+@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.
-@example
-x/10i $pc
-@end example
+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.
-@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
+@code{add-symbol-file} will not repeat if you press @key{RET} after using it.
-@example
-x/7
-@end example
+@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}), 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.
-@noindent
-in which the format and address are allowed to default.
+@end table
-@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{$__}.
+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.
-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{$__}.
+@cindex shared libraries
-If the @samp{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.
+_GDBN__ supports the SunOS shared library format. _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__ won't understand references to a
+function in a shared library, however---unless you're 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're from a shared lib
-@node Auto Display, Value History, Output formats, Data
-@section Automatic Display
-@cindex automatic display
-@cindex display of expressions
+@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.
-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.
-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:
+@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
-@example
-2: foo = 38
-3: bar[5] = (struct hack *) 0x3804
-@end example
+@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're 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 (@xref{Messages/Warnings}).
-@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.
+The messages currently printed, and their meanings, are:
@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}.
-
-@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}.
+@item inner block not inside outer block in @var{symbol}
-@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}.
+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.
-@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.
+_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 disable display @var{dnums}@dots{}
-@kindex disable display
-Disable the display of item numbers @var{dnums}. A disabled display
-item is not printed automatically, but is not forgotten. It may be
-enabled again later.
+@item block at @var{address} out of order
-@item enable display @var{dnums}@dots{}
-@kindex enable display
-Enable display of item numbers @var{dnums}. It becomes effective once
-again in auto display of its expression, until you specify otherwise.
+The symbol information for symbol scope blocks should occur in
+order of increasing addresses. This error indicates that it does not
+do so.
-@item display
-Display the current values of the expressions on the list, just as is
-done when the program stops.
+_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}.)
-@item info display
-@kindex info display
-Print the list of expressions previously set up to display
-automatically, each one with its item number, but without showing the
-values. This includes disabled expressions, which are marked as such.
-It also includes expressions which would not be displayed right now
-because they refer to automatic variables not currently available.
-@end table
+@item bad block start address patched
-@node Value History, Convenience Vars, Auto Display, Data
-@section Value History
+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.
-@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.
+_GDBN__ circumvents the problem by treating the symbol scope block as
+starting on the previous source line.
-@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{$@var{num} = }
-before the value; here @var{num} is the history number.
+@item bad string table offset in symbol @var{n}
-To refer to any previous value, use @samp{$} 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{$}.
+@cindex foo
+Symbol number @var{n} contains a pointer into the string table which is
+larger than the size of the string table.
-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
+_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.
-@example
-p *$
-@end example
+@item unknown symbol type @code{0x@var{nn}}
-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:
+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.
-@example
-p *$.next
-@end example
+_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 @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.
-@noindent
-It might be useful to repeat this command many times by typing @key{RET}.
+@item stub type has NULL name
+_GDBN__ could not find the full definition for a struct or class.
-Note that the history records values, not expressions. If the value of
-@code{x} is 4 and you type this command:
+@ignore
+@c this is #if 0'd in dbxread.c as of (at least!) 17 may 1991
+@item const/volatile indicator missing, got '@var{X}'
-@example
-print x
-set x=5
-@end example
+The symbol information for a C++ member function is missing some
+information that the compiler should have output for it.
+@end ignore
-@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 C++ type mismatch between compiler and debugger
-@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 info values @var{n}
-Print ten history values centered on history item number @var{n}.
+_GDBN__ could not parse a type specification output by the compiler
+for some C++ object.
-@item info values +
-Print ten history values just after the values last printed.
@end table
-@node Convenience Vars, Registers, Value History, Data
-@section Convenience Variables
+@node Targets, Controlling _GDBN__, _GDBN__ Files, 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.
-@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.
+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 @code{file} or @code{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 @code{target} command.
-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}).
+@menu
+* Active Targets:: Active Targets
+* Target Commands:: Commands for Managing Targets
+* Remote:: Remote Debugging
+@end menu
-You can save a value in a convenience variable with an assignment
-expression, just as you would set a variable in your program. Example:
+@node Active Targets, Target Commands, Targets, Targets
+@section Active Targets
+@cindex stacking targets
+@cindex active targets
+@cindex multiple targets
-@example
-set $foo = *object_ptr
-@end example
+Targets are managed in three @dfn{strata} that correspond to different
+classes of target: processes, core files, and executable files. This
+allows you to (for example) start a process and inspect its activity
+without abandoning your work on a core file.
-@noindent
-would save in @code{$foo} the value contained in the object pointed to by
-@code{object_ptr}.
+More than one target can potentially respond to a request. In
+particular, when you access memory _GDBN__ will examine the three strata of
+targets until it finds a target that can handle that particular address.
+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.
-Using a convenience variable for the first time creates it; but its value
-is @code{void} until you assign a new value. You can alter the value with
-another assignment at any time.
+When you specify a new target in a given stratum, it replaces any target
+previously in that stratum.
-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.
+To get rid of a target without replacing it, use the @code{detach}
+command. The related command @code{attach} provides you with a way of
+choosing a particular running process as a new target. @xref{Attach}.
-@table @code
-@item info convenience
-@kindex info convenience
-Print a list of convenience variables used so far, and their values.
-Abbreviated @samp{i con}.
-@end table
+@node Target Commands, Remote, Active Targets, Targets
+@section Commands for Managing Targets
-One of the ways to use a convenience variable is as a counter to be
-incremented or a pointer to be advanced. For example:
+@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.
-@example
-set $i = 0
-print bar[$i++]->contents
-@i{@dots{}repeat that command by typing @key{RET}.}
-@end example
+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.
-Some convenience variables are created automatically by _GDBN__ and given
-values likely to be useful.
+The @code{target} command will not repeat if you press @key{RET} again
+after executing the command.
-@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}.
+@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}).
-@item $__
-The variable @code{$__} is automatically set by the @samp{x} command
-to the value found in the last address examined.
+@item help target @var{name}
+Describe a particular target, including any parameters necessary to
+select it.
@end table
-@node Registers, , Convenience Vars, Data
-@section Registers
+Here are some common targets (available, or not, depending on the _GDBN__
+configuration):
-@cindex registers
-Machine register contents can be referred to 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}}).
+@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}}.
-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.
+@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 _GDBN__-specific protocol. The argument @var{dev}
+specifies what serial device to use for the connection (e.g.
+@file{/dev/ttya}). @xref{Remote}.
+
+_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}.
-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}).
+_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.
+@file{/dev/ttya}. @xref{i960-Nindy Remote}.
-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.
+_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}.
+_fi__(_VXWORKS__)
+@end table
-@table @code
-@item info registers
-@kindex info registers
-Print the names and relativized values of all registers.
+_if__(_GENERIC__)
+Different targets are available on different configurations of _GDBN__; your
+configuration may have more or fewer targets.
+_fi__(_GENERIC__)
-@item info registers @var{regname}
-Print the relativized value of register @var{regname}. @var{regname}
-may be any register name valid on the machine you are using, with
-or without the initial @samp{$}.
-@end table
+@node Remote, , Target Commands, Targets
+@section Remote Debugging
+@cindex remote debugging
-@subsection Examples
+_if__(_GENERIC__)
+@menu
+_include__(gdbinv-m.m4)<>_dnl__
+@end menu
+_fi__(_GENERIC__)
-You could print the program counter in hex with
+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 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.
-@example
-p/x $pc
-@end example
+Some configurations of _GDBN__ have special serial or TCP/IP interfaces
+to make this work with particular debugging targets. In addition,
+_GDBN__ comes with a generic serial protocol (specific to _GDBN__, 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 _GDBN__.
-@noindent
-or print the instruction to be executed next with
+To use the _GDBN__ remote serial protocol, the program to be debugged on
+the remote machine needs to contain a debugging stub which talks to
+_GDBN__ over the serial line. Several working remote stubs are
+distributed with _GDBN__; see the @file{README} file in the _GDBN__
+distribution for more information.
-@example
-x/i $pc
-@end example
+For details of this communication protocol, see the comments in the
+_GDBN__ source file @file{remote.c}.
-@noindent
-or add four to the stack pointer with
+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 @code{target remote} command with a device
+name as an argument. For example:
@example
-set $sp += 4
+target remote /dev/ttyb
@end example
@noindent
-The last is a way of removing one word from the stack, on machines where
-stacks grow downward in memory (most machines, nowadays). This assumes
-that the innermost stack frame is selected. Setting @code{$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
-
-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.
+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.
-@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.
+Now you can use all the usual commands to examine and change data and to
+step and continue the remote program.
-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.
+To resume the remote program and stop debugging it, use the @code{detach}
+command.
-@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}.
+Other remote targets may be available in your
+configuration of _GDBN__; use @code{help targets} to list them.
-@item whatis
-Print the data type of @code{$}, the last value in the value history.
+_if__(_GENERIC__)
+@c Text on starting up GDB in various specific cases; it goes up front
+@c in manuals configured for any of those particular situations, here
+@c otherwise.
+_include__(gdbinv-s.m4)
+_fi__(_GENERIC__)
-@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
+@node Controlling _GDBN__, Sequences, Targets, Top
+@chapter Controlling _GDBN__
-@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;@}}
+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}; other settings are described here.
-@item info sources
-@kindex info sources
-Print the names of all source files in the program for which there
-is debugging information.
+@menu
+* Prompt:: Prompt
+* Editing:: Command Editing
+* History:: Command History
+* Screen Size:: Screen Size
+* Numbers:: Numbers
+* Messages/Warnings:: Optional Warnings and Messages
+@end menu
-@item info functions
-@kindex info functions
-Print the names and data types of all defined functions.
+@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.
-@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}.
+@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
-@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 Editing, History, Prompt, Controlling _GDBN__
+@section Command Editing
+@cindex readline
+@cindex command line editing
+_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.
-@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}.
+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).
-@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
+@item set editing off
+Disable command line editing.
-@item printsyms @var{filename}
-@kindex printsyms
-Write a complete dump of the debugger's symbol data into the
-file @var{filename}.
+@kindex show editing
+@item show editing
+Show whether command line editing is enabled.
@end table
-@node Altering, Sequences, Symbols, Top
-@chapter Altering Execution
+@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.
-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.
+@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.
-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.
+@item set history save off
+Stop recording command history in a file.
-@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
+@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
-@node Assignment, Jumping, Altering, Altering
-@section Assignment to Variables
+@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.
-@cindex assignment
-@cindex setting variables
-To alter the value of a variable, evaluate an assignment expression.
-@xref{Expressions}. For example,
+The commands to control history expansion are:
-@example
-print x=4
-@end example
+@table @code
-@noindent
-would store the value 4 into the variable @code{x}, and then print
-the value of the assignment expression (which is 4).
+@kindex set history expansion
+@item set history expansion on
+@itemx set history expansion
+Enable history expansion. History expansion is off by default.
-All the assignment operators of C are supported, including the
-increment operators @samp{++} and @samp{--}, and combining
-assignments such as @samp{+=} and @samp{<<=}.
+@item set history expansion off
+Disable history expansion.
-@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.
+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
-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.
+@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
-_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?
+@end table
-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
+@table @code
+@kindex show commands
+@item show commands
+Display the last ten commands in the command history.
-@example
-set @{int@}0x83040 = 4
-@end example
+@item show commands @var{n}
+Print ten commands centered on command number @var{n}.
-would store the value 4 into that memory location.
+@item show commands +
+Print ten commands just after the commands last printed.
-@node Jumping, Signaling, Assignment, Altering
-@section Continuing at a Different Address
+@end table
-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:
+@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 jump @var{linenum}
-@kindex jump
-Resume execution at line number @var{linenum}. Execution may stop
-immediately if there is a breakpoint there.
-
-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.
+@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.
-@item jump *@var{address}
-Resume execution at the instruction at address @var{address}.
+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
-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 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}.
+will set the base to decimal. On the other hand, @samp{set radix 10}
+will leave the radix unchanged no matter what it was.
-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 radix
+@item show radix
+Display the current default base for numeric input and display.
-@node Signaling, Returning, Jumping, Altering
-@section Giving the Program a Signal
+@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 won't 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}, in the description of the command
+@code{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 @code{symbol-file} in @ref{Files}).
+@end ignore
@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 verbose
+@item set verbose on
+Enables _GDBN__'s output of certain informational messages.
-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.
+@item set verbose off
+Disables _GDBN__'s output of certain informational messages.
+
+@kindex show verbose
+@item show verbose
+Displays whether @code{set verbose} is on or off.
@end table
-@node Returning, Calling, Signaling, Altering
-@section Returning from a Function
+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}).
@table @code
-@item return
-@cindex returning from a function
-@kindex return
-You can cancel execution of a function call with the @samp{return}
-command.
+@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.
+
+@kindex show complaints
+@item show complaints
+Displays how many symbol complaints _GDBN__ is permitted to produce.
@end table
-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.
+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:
+@example
+(_GDBP__) run
+The program being debugged has been started already.
+Start it from the beginning? (y or n)
+@end example
-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.
+If you're willing to unflinchingly face the consequences of your own
+commands, you can disable this ``feature'':
-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.
+@table @code
+@kindex set confirm
+@cindex flinching
+@cindex confirmation
+@cindex stupid questions
+@item set confirm off
+Disables confirmation requests.
-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 set confirm on
+Enables confirmation requests (the default).
-@node Calling, , Returning, Altering
-@comment node-name, next, previous, up
-@section Calling your Program's Functions
+@item show confirm
+@kindex show confirm
+Displays state of confirmation requests.
+@end table
-@cindex calling functions
-@kindex call
+@c FIXME this doesn't 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're running on one of these systems, you can allow _GDBN__ to
+reload the symbols for automatically relinked modules:@refill
@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
+Don't replace symbol definitions when re-encountering object files of
+the same name. This is the default state; if you're 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
+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.
@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 info user
+@itemx info user @var{commandname}
+@kindex info 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}.) 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.
+@c I don't consider backslash-space a standard C escape sequence
+@c 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
+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 FIXME: verify hard copy actually issues enspaces for '@ '! Will this
+@c confuse texinfo?
A backslash at the end of @var{text} can be used, as in C, to continue
the command onto subsequent lines. For example,
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
letter.
@end table
-@node Emacs, Remote, Sequences, Top
+@node Emacs, _GDBN__ Bugs, Sequences, Top
@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
-Explicit _GDBN__ @samp{list} or search commands still produce output as
+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__ @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 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__ @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,
@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 the 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}.@refill
@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 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
+@node _GDBN__ Bugs, Renamed Commands, Emacs, Top
@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.
-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 don't 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
stray memory reference which happens to fetch from the location where that
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 isn't as important 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
the bug in the current version of _GDBN__.
``_GCC__-1.37.1''.
@item
-What compiler (and its version) was used to compile _GDBN__.
-
-@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.
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
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 won't match those in your
sources. Your line numbers would convey no useful information to us.
@end itemize
@end itemize
@iftex
-@include readline/inc-readline.texinfo
-@include readline/inc-history.texinfo
+@include rdl-apps.texi
@end iftex
-@node Installing _GDBN__, License, _GDBN__ Bugs, Top
+@node Renamed Commands, Installing _GDBN__, _GDBN__ Bugs, Top
+@appendix Renamed Commands
+
+The following commands were renamed in _GDBN__ 4.0, 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
+
+@ifinfo
+@example
+OLD COMMAND NEW COMMAND
+--------------- -------------------------------
+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
+@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
+
+@node Installing _GDBN__, Copying, Renamed Commands, Top
@appendix Installing _GDBN__
@cindex configuring _GDBN__
@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,
+_GDBN__ comes with a @code{configure} script that automates the process
+of preparing _GDBN__ for installation; you can then use @code{make} to
+build the @code{_GDBP__} program.
+
+The _GDBP__ distribution includes all the source code you need for
+_GDBP__ in a single directory @file{gdb-_GDB_VN__}. That directory in turn
+contains:
+
+@table @code
+@item gdb-_GDB_VN__/configure
+Overall script for configuring _GDBN__ and all its supporting libraries.
+
+@item gdb-_GDB_VN__/gdb
+the source specific to _GDBN__ 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
+@end table
+@noindent
+Each of these directories has its own @code{configure} script, which are
+used by the overall @code{configure} script in @file{gdb-_GDB_VN__}.
+
+It is most convenient to run @code{configure} from the @file{gdb-_GDB_VN__}
+directory. The simplest way to configure and build _GDBN__ is the
+following:
+@example
+cd gdb-_GDB_VN__
+./configure @var{host}
+make
+@end example
+@noindent
+where @var{host} is something like @samp{sun4} or @samp{decstation}, that
+identifies the platform where _GDBN__ will run. This builds the three
+libraries @file{bfd}, @file{readline}, and @file{libiberty}, then
+@code{gdb} itself. The configured source files, and the binaries, are
+left in the corresponding source directories.
+
+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; some systems
+refuse to let _GDBN__ debug child processes whose programs are not
+readable, and _GDBN__ uses the shell to start your program.
+
+@menu
+* Subdirectories:: Configuration subdirectories
+* Config Names:: Specifying names for hosts and targets
+* configure Options:: Summary of options for configure
+* Formatting Documentation:: How to format and print _GDBN__ documentation
+@end menu
+
+
+@node Subdirectories, Config Names, Installing _GDBN__, Installing _GDBN__
+@section Configuration Subdirectories
+If you want to run _GDBN__ versions for several host or target machines,
+you'll need a different _GDBP__ 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. 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
+_GDBP__ program specified there.
+
+@code{configure} creates these subdirectories for you when you
+simultaneously specify several configurations; but it's a good habit
+even for a single configuration. You can specify the use of
+subdirectories using the @samp{+subdirs} option (abbreviated
+@samp{+sub}). For example, you can build _GDBN__ on a Sun 4 as follows:
@example
-config.gdb sun3os4
+@group
+cd gdb-_GDB_VN__
+./configure +sub sun4
+cd Host-sparc-sun-sunos4/Target-sparc-sun-sunos4
make
+@end group
+@end example
+
+When @code{configure} uses subdirectories to build programs or
+libraries, it creates nested directories
+@file{Host-@var{host}/Target-@var{target}}. (As you see in the example,
+the names used for @var{host} and @var{target} may be expanded from your
+@code{configure} argument; @pxref{Config Names}). @code{configure} uses
+these two directory levels because _GDBN__ can be configured for
+cross-compiling: _GDBN__ can run on one machine (the host) while
+debugging programs that run on another machine (the target). You
+specify cross-debugging targets by giving the
+@samp{+target=@var{target}} option to @code{configure}. Specifying only
+hosts still gives you two levels of subdirectory for each host, with the
+same configuration suffix on both; that is, if you give any number of
+hosts but no targets, _GDBN__ will be configured for native debugging on
+each host. On the other hand, whenever you specify both hosts and
+targets on the same command line, @code{configure} creates all
+combinations of the hosts and targets you list.@refill
+
+When you run @code{make} to build a program or library, you must run it
+in a configured directory. If you made a single configuration,
+without subdirectories, run @code{make} in the source directory.
+If you have @file{Host-@var{host}/Target-@var{target}} subdirectories,
+run @code{make} in those subdirectories.
+
+Each @code{configure} and @code{Makefile} under each source directory
+runs recursively, so that typing @code{make} in @file{gdb-_GDB_VN__} (or in a
+@file{gdb-_GDB_VN__/Host-@var{host}/Target-@var{target}} subdirectory)
+builds all the required libraries, then _GDBN__.@refill
+
+If you run @code{configure} from a directory (such as @file{gdb-_GDB_VN__}) that
+contains source directories for multiple libraries or programs,
+@code{configure} creates the @file{Host-@var{host}/Target-@var{target}}
+subdirectories in each library or program's source directory. For
+example, typing:
+@example
+cd gdb-_GDB_VN__
+configure sun4 +target=vxworks960
+@end example
+@noindent
+creates the following directories:
+@smallexample
+gdb-_GDB_VN__/Host-sparc-sun-sunos4/Target-i960-wrs-vxworks
+gdb-_GDB_VN__/bfd/Host-sparc-sun-sunos4/Target-i960-wrs-vxworks
+gdb-_GDB_VN__/gdb/Host-sparc-sun-sunos4/Target-i960-wrs-vxworks
+gdb-_GDB_VN__/libiberty/Host-sparc-sun-sunos4/Target-i960-wrs-vxworks
+gdb-_GDB_VN__/readline/Host-sparc-sun-sunos4/Target-i960-wrs-vxworks
+@end smallexample
+@noindent
+The @code{Makefile} in
+@smallexample
+gdb-_GDB_VN__/Host-sparc-sun-sunos4/Target-i960-wrs-vxworks
+@end smallexample
+@noindent
+will @code{cd} to the appropriate lower-level directories, for example:
+@smallexample
+gdb-_GDB_VN__/bfd/Host-sparc-sun-sunos4/Target-i960-wrs-vxworks
+@end smallexample
+@noindent
+building each in turn.
+
+When you have multiple hosts or targets configured, 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.
+
+
+@iftex
+@c FIXME isn't there something kinder, gentler than @page?
+@page
+@end iftex
+@node Config Names, configure Options, Subdirectories, Installing _GDBN__
+@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 full name of that
+configuration specifies that the architecture is @samp{sparc}, the
+vendor is @samp{sun}, and the operating system is @samp{sunos4}.
+
+@iftex
+@c I know this is ugly, but @group is useless except in examples now...
+@c (using texinfo 2.52 or so)
+@page
+@end iftex
+
+The following table shows all the architectures, hosts, and OS prefixes
+that @code{configure} recognizes in _GDBN__ _GDB_VN__. Entries in the ``OS
+prefix'' column ending in a @samp{*} may be followed by a release number.
+
+@ifinfo
+@example
+
+ARCHITECTURE VENDOR OS prefix
+------------+-------------+-------------
+ | |
+ 580 | altos | aix*
+ a29k | amdahl | amigados
+ alliant | aout | aout
+ arm | apollo | bout
+ c1 | att | bsd*
+ c2 | bull | coff
+ cray2 | bcs | ctix*
+ h8300 | bout | dynix*
+ i386 | cbm | esix*
+ i860 | coff | hpux*
+ i960 | convergent | irix*
+ m68000 | convex | isc*
+ m68k | cray | kern
+ m88k | dec | mach*
+ mips | encore | newsos*
+ ns32k | gould | nindy*
+ pyramid | hp | none
+ romp | ibm | osf*
+ rs6000 | intel | sco*
+ rtpc | isi | sunos*
+ sparc | little | svr4
+ tahoe | mips | sym*
+ tron | motorola | sysv*
+ vax | ncr | ultrix*
+ xmp | next | unicos
+ ymp | none | unos*
+ | nyu | uts
+ | sco | v88r*
+ | sequent | vms*
+ | sgi | vxworks*
+ | sony |
+ | sun |
+ | unicom |
+ | utek |
+ | wrs |
+
+@end example
+@quotation
+@emph{Warning:} Many combinations of architecture, vendor, and OS are
+untested.
+@end quotation
+@end ifinfo
+@c FIXME: this table is probably screwed in @smallbook. Try setting
+@c FIXME...smallbook fonts?
+@tex
+%\vskip\parskip
+\vskip \baselineskip
+\halign{\hskip\parindent\tt #\hfil &\qquad#&\tt #\hfil &\qquad#&\tt
+#\hfil &\qquad\qquad\it #\hfil\cr
+{\bf Architecture} &&{\bf Vendor} &&{\bf OS prefix}\cr
+\multispan5\hrulefill\cr
+ 580 && altos && aix* \cr
+ a29k && amdahl && amigados\cr
+ alliant && aout && aout \cr
+ arm && apollo && bout \cr
+ c1 && att && bsd* \cr
+ c2 && bull && coff \cr
+ cray2 && bcs && ctix* \cr
+ h8300 && bout && dynix* \cr
+ i386 && cbm && esix* \cr
+ i860 && coff && hpux* &Warning: \cr
+ i960 && convergent && irix* &Many combinations \cr
+ m68000 && convex && isc* &of architecture, vendor \cr
+ m68k && cray && kern &and OS are untested. \cr
+ m88k && dec && mach* \cr
+ mips && encore && newsos* \cr
+ ns32k && gould && nindy* \cr
+ pyramid && hp && none \cr
+ romp && ibm && osf* \cr
+ rs6000 && intel && sco* \cr
+ rtpc && isi && sunos* \cr
+ sparc && little && svr4 \cr
+ tahoe && mips && sym* \cr
+ tron && motorola && sysv* \cr
+ vax && ncr && ultrix* \cr
+ xmp && next && unicos \cr
+ ymp && none && unos* \cr
+ && nyu && uts \cr
+ && sco && v88r* \cr
+ && sequent && vms* \cr
+ && sgi && vxworks*\cr
+ && sony &&\cr
+ && sun &&\cr
+ && unicom &&\cr
+ && utek &&\cr
+ && wrs &&\cr
+}
+@end tex
+
+The @code{configure} script accompanying _GDBN__ _GDB_VN__ 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-sunos4
+% sh config.sub sun3
+m68k-sun-sunos4
+% sh config.sub decstation
+mips-dec-ultrix
+% sh config.sub hp300bsd
+m68k-hp-bsd
+% sh config.sub i386v
+i386-none-sysv
+% sh config.sub i486v
+*** No vendor: configuration `i486v' not recognized
@end example
+@node configure Options, Formatting Documentation, Config Names, Installing _GDBN__
+@section @code{configure} Options
+
+Here is a summary of all the @code{configure} options and arguments that
+you might use for building _GDBN__:
+
+@example
+configure @r{[}+destdir=@var{dir}@r{]} @r{[}+subdirs@r{]} @r{[}+norecur@r{]} @r{[}+rm@r{]}
+ @r{[}+target=@var{target}@dots{}@r{]} @var{host}@dots{}
+@end example
@noindent
-is all that's required to install _GDBN__ on a Sun 3 running SunOS 4.
+You may introduce options with the character @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 +destdir=@var{dir}
+@var{dir} is an installation directory @emph{path prefix}. After you
+configure with this option, @code{make install} will install _GDBN__ as
+@file{@var{dir}/bin/_GDBP__}, and the libraries in @file{@var{dir}/lib}.
+If you specify @samp{+destdir=/usr/local}, for example, @code{make
+install} creates @file{/usr/local/bin/gdb}.@refill
+
+@item +subdirs
+Write configuration specific files in subdirectories of the form
+@example
+Host-@var{host}/Target-@var{target}
+@end example
+@noindent
+(and configure the @code{Makefile} to write binaries there too).
+Without this option, if you specify only one configuration for _GDBN__,
+@code{configure} will use the same directory for source, configured
+files, and binaries. This option is used automatically if you specify
+more than one @var{host} or more than one @samp{+target=@var{target}}
+option on the @code{configure} command line.
+
+@item +norecur
+Configure only the directory where @code{configure} is executed; do not
+propagate configuration to subdirectories.
+
+@item +rm
+Remove the configuration that the other arguments specify.
+
+@c This doesn't work (yet if ever). FIXME.
+@c @item +parse=@var{lang} @dots{}
+@c Configure the _GDBN__ expression parser to parse the listed languages.
+@c @samp{all} configures _GDBN__ for all supported languages. To get a
+@c list of all supported languages, omit the argument. Without this
+@c option, _GDBN__ is configured to parse all supported languages.
+
+@item +target=@var{target} @dots{}
+Configure _GDBN__ for cross-debugging programs running on each specified
+@var{target}. You may specify as many @samp{+target} options as you
+wish. Without this option, _GDBN__ is configured to debug programs that
+run on the same machine (@var{host}) as _GDBN__ itself.
+
+There is no convenient way to generate a list of all available targets.
+
+@item @var{host} @dots{}
+Configure _GDBN__ to run on each specified @var{host}. You may specify as
+many host names as you wish.
+
+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 _GDBN__ or its supporting libraries.
+
+@node Formatting Documentation, , configure Options, Installing _GDBN__
+@section Formatting the Documentation
+
+@cindex _GDBN__ reference card
+@cindex reference card
+The _GDBN__ _GDB_VN__ release includes an already-formatted reference card,
+ready for printing on a PostScript printer, as @file{gdb-_GDB_VN__/gdb/refcard.ps}.
+It uses the most common PostScript fonts: the Times family, Courier, and
+Symbol. If you have a PostScript printer, you can print the reference
+card by just sending @file{refcard.ps} to the printer.
+
+The release also includes the online Info version of this manual already
+formatted: the main Info file is @file{gdb-_GDB_VN__/gdb/gdb.info}, and it
+refers to subordinate files matching @samp{gdb.info*} in the same
+directory.
+
+If you want to make these Info files yourself from the _GDBN__ manual's
+source, you need the GNU @code{makeinfo} program. Once you have it, you
+can type
+@example
+cd gdb-_GDB_VN__/gdb
+make gdb.info
+@end example
+@noindent
+to make the Info file.
+
+If you want to format and print copies of the manual, you need several
+things:
+@itemize @bullet
+@item
+@TeX{}, the public domain typesetting program written by Donald Knuth,
+must be installed on your system and available through your execution
+path.
+@item
+@file{gdb-_GDB_VN__/texinfo}: @TeX{} macros defining the GNU
+Documentation Format.
+@item
+@emph{A @sc{dvi} output program.} @TeX{} doesn't actually make marks on
+paper; it produces output files called @sc{dvi} files. If your system
+has @TeX{} installed, chances are it has a program for printing out
+these files; one popular example is @code{dvips}, which can print
+@sc{dvi} files on PostScript printers.
+@end itemize
+@noindent
+Once you have these things, you can type
+@example
+cd gdb-_GDB_VN__/gdb
+make gdb.dvi
+@end example
+@noindent
+to format the text of this manual, and print it with the usual output
+method for @TeX{} @sc{dvi} files at your site.
+
+If you want to print the reference card, but don't have a PostScript
+printer, or you want to use Computer Modern fonts instead,
+you can still print it if you have @TeX{}. Format the reference card by typing
+@example
+cd gdb-_GDB_VN__/gdb
+make refcard.dvi
+@end example
+@noindent
+
+The _GDBN__ 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.
+
+
+@node Copying, Index, Installing _GDBN__, 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:
+@alphaenumerate
@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
-
-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.
+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 alphaenumerate
+
+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
+@alphaenumerate
@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
-
-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.
+received the program in object code or executable form with such
+an offer, in accord with Subsection b above.)
+@end alphaenumerate
+
+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.}
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.
+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
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!
+@end example
-@node Commands, Concepts, License, Top
-@unnumbered Command Index
+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.
-@printindex ky
-@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\/} and}
+\centerline{{\sl\fontname\tensl\/}}
+\centerline{are used for emphasis.}\vfill}
+\page\colophon
+@end tex
+
@contents
@bye
projects / binutils.git / blobdiff