-_dnl__ -*-Texinfo-*-
-_dnl__ Copyright (c) 1988 1989 1990 1991 Free Software Foundation, Inc.
-\input texinfo
+_dnl__ -*-Texinfo-*-
+_dnl__ Copyright (c) 1988 1989 1990 1991 1992 Free Software Foundation, Inc.
+_dnl__ $Id$
+\input texinfo @c -*-texinfo-*-
+@c Copyright (c) 1988 1989 1990 1991 1992 Free Software Foundation, Inc.
+@c %**start of header
@setfilename _GDBP__.info
-@c $Id$
+_if__(_GENERIC__)
+@settitle _GDBN__, The GNU Debugger
+_fi__(_GENERIC__)
+_if__(!_GENERIC__)
+@settitle _GDB__, The GNU Debugger (_HOST__)
+_fi__(!_GENERIC__)
+@setchapternewpage odd
+@c @smallbook
+@c @cropmarks
+@c %**end of header
+
+@finalout
+@syncodeindex ky cp
+
+_0__@c ===> NOTE! <==_1__
+@c Determine the edition number in *three* places by hand:
+@c 1. First ifinfo section 2. title page 3. top node
+@c To find the locations, search for !!set
+
+@c The following is for Pesch for his RCS system.
+@c This revision number *not* the same as the Edition number.
+@tex
+\def\$#1${{#1}} % Kluge: collect RCS revision info without $...$
+\xdef\manvers{\$Revision$} % For use in headers, footers too
+@end tex
+
+@c GDB CHANGELOG CONSULTED BETWEEN:
+@c Fri Oct 11 23:27:06 1991 John Gilmore (gnu at cygnus.com)
+@c Sat Dec 22 02:51:40 1990 John Gilmore (gnu at cygint)
+
@c THIS MANUAL REQUIRES TEXINFO-2 macros and info-makers to format properly.
-@c
-@c NOTE: this manual is marked up for preprocessing with a collection
-@c of m4 macros called "pretex.m4". If you see <_if__> and <_fi__>
-@c scattered around the source, you have the full source before
-@c preprocessing; if you don't, you have the source configured for
-@c _HOST__ architectures (and you can of course get the full source,
-@c with all configurations, from wherever you got this).
+
+@ifinfo
+@format
+START-INFO-DIR-ENTRY
+* Gdb: (gdb). The GNU debugger.
+END-INFO-DIR-ENTRY
+@end format
+@end ifinfo
_if__(0)
+NOTE: this manual is marked up for preprocessing with a collection
+of m4 macros called "pretex.m4".
+
THIS IS THE SOURCE PRIOR TO PREPROCESSING. The full source needs to
be run through m4 before either tex- or info- formatting: for example,
_0__
- m4 pretex.m4 none.m4 m680x0.m4 gdb.texinfo >gdb-680x0.texinfo
-_1__
+ m4 pretex.m4 none.m4 all.m4 gdb.texinfo >gdb-all.texinfo
will produce (assuming your path finds either GNU m4 >= 0.84, or SysV
-m4; Berkeley won't do) a file suitable for formatting. See the text in
+m4; Berkeley will not do) a file suitable for formatting. See the text in
"pretex.m4" for a fuller explanation (and the macro definitions).
+_1__
_fi__(0)
-@tex
-\def\$#1${{#1}} % Kluge: collect RCS revision info without $...$
-\xdef\manvers{\$Revision$} % For use in headers, footers too
-@end tex
@c
-@syncodeindex ky cp
-@c FOR UPDATES LEADING TO THIS DRAFT, GDB CHANGELOG CONSULTED BETWEEN:
-@c Sun May 19 05:36:59 1991 John Gilmore (gnu at cygint.cygnus.com)
-@c Sat Dec 22 02:51:40 1990 John Gilmore (gnu at cygint)
@ifinfo
This file documents the GNU debugger _GDBN__.
-Copyright (C) 1988, 1989, 1990, 1991 Free Software Foundation, Inc.
+@c !!set edition, date, version
+This is Edition 4.05, June 1992,
+of @cite{Using GDB: A Guide to the GNU Source-Level Debugger}
+for GDB Version _GDB_VN__.
+
+Copyright (C) 1988, 1989, 1990, 1991, 1992 Free Software Foundation, Inc.
Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
included in a translation approved by the Free Software Foundation
instead of in the original English.
@end ifinfo
-@smallbook
-@setchapternewpage odd
-_if__(_GENERIC__)
-@settitle Using _GDBN__ (v4.0)
-_fi__(_GENERIC__)
-_if__(!_GENERIC__)
-@settitle Using _GDBN__ v4.0 (_HOST__)
-_fi__(!_GENERIC__)
-@iftex
-@finalout
-@end iftex
+
@titlepage
-@title{Using _GDBN__}
-@subtitle{A Guide to the GNU Source-Level Debugger}
+@title Using _GDBN__
+@subtitle The GNU Source-Level Debugger
_if__(!_GENERIC__)
-@subtitle{On _HOST__ Systems}
+@subtitle on _HOST__ Systems
_fi__(!_GENERIC__)
@sp 1
-@c Maybe crank this up to "Fourth Edition" when released at FSF
-@c @subtitle Third Edition---_GDBN__ version 4.0
-@subtitle _GDBN__ version 4.0
-@subtitle July 1991
-@author{Richard M. Stallman@qquad @hfill Free Software Foundation}
-@author{Roland H. Pesch@qquad @hfill Cygnus Support}
+@c !!set edition, date, version
+@subtitle Edition 4.05, for _GDBN__ version _GDB_VN__
+@subtitle June 1992
+@author by Richard M. Stallman and Roland H. Pesch
@page
@tex
{\parskip=0pt
-\hfill rms\@ai.mit.edu, pesch\@cygnus.com\par
+\hfill pesch\@cygnus.com\par
\hfill {\it Using _GDBN__}, \manvers\par
\hfill \TeX{}info \texinfoversion\par
}
@end tex
@vskip 0pt plus 1filll
-Copyright @copyright{} 1988, 1989, 1990, 1991 Free Software Foundation, Inc.
+Copyright @copyright{} 1988, 1989, 1990, 1991, 1992 Free Software Foundation, Inc.
Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
@end titlepage
@page
-@node Top, Summary, (dir), (dir)
@ifinfo
-This file describes version 4.0 of GDB, the GNU symbolic debugger.
+@node Top, Summary, (dir), (dir)
+@top _GDBN__, the GNU symbolic debugger
+
+This file describes _GDBN__, the GNU symbolic debugger.
+
+@c !!set edition, date, version
+This is Edition 4.05, June 1992, for GDB Version _GDB_VN__.
@end ifinfo
@menu
-* Summary:: Summary of _GDBN__
-* New Features:: New Features in _GDBN__ version 4.0
-* Sample Session:: A Sample _GDBN__ Session
-* Invocation:: Getting In and Out of _GDBN__
-* Commands::
-* Running:: Running Programs Under _GDBN__
-* Stopping:: Stopping and Continuing
-* Stack:: Examining the Stack
-* Source:: Examining Source Files
-* Data:: Examining Data
-* Symbols:: Examining the Symbol Table
-* Altering:: Altering Execution
-* _GDBN__ 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
+* Summary:: Summary of _GDBN__
+* New Features:: New features since GDB version 3.5
+* Sample Session:: A sample _GDBN__ session
+* Invocation:: Getting in and out of _GDBN__
+* Commands:: _GDBN__ commands
+* Running:: Running programs under _GDBN__
+* Stopping:: Stopping and continuing
+* Stack:: Examining the stack
+* Source:: Examining source files
+* Data:: Examining data
+* Languages:: Using _GDBN__ with different languages
+* Symbols:: Examining the symbol table
+* Altering:: Altering execution
+* _GDBN__ Files:: _GDBN__'s files
+* Targets:: Specifying a debugging target
+* Controlling _GDBN__:: Controlling _GDBN__
+* Sequences:: Canned sequences of commands
+* Emacs:: Using _GDBN__ under GNU Emacs
+* _GDBN__ Bugs:: Reporting bugs in _GDBN__
+* Renamed Commands::
+* Formatting Documentation:: How to format and print GDB documentation
+* Installing GDB:: Installing GDB
+* Copying:: GNU GENERAL PUBLIC LICENSE
+* Index:: Index
+
--- The Detailed Node Listing ---
Summary of _GDBN__
-* Free Software:: Free Software
-* Contributors:: Contributors to _GDBN__
+* Free Software:: Freely redistributable software
+* Contributors:: Contributors to _GDBN__
Getting In and Out of _GDBN__
-* Starting _GDBN__:: Starting _GDBN__
-* Leaving _GDBN__:: Leaving _GDBN__
-* Shell Commands:: Shell Commands
+* Invoking _GDBN__:: How to start _GDBN__
+* Leaving _GDBN__:: How to quit _GDBN__
+* Shell Commands:: How to use shell commands inside _GDBN__
Starting _GDBN__
-* File Options:: Choosing Files
-* Mode Options:: Choosing Modes
+* File Options:: Choosing Files
+* Mode Options:: Choosing Modes
_GDBN__ Commands
-* Command Syntax:: Command Syntax
-* Help:: Getting Help
+* Command Syntax:: Command Syntax
+* Completion:: Command Completion
+* Help:: Getting Help
Running Programs Under _GDBN__
-* Compilation:: Compiling for Debugging
-* Starting:: Starting your Program
-* Arguments:: Your Program's Arguments
-* Environment:: Your Program's Environment
-* Working Directory:: Your Program's Working Directory
-* Input/Output:: Your Program's Input and Output
-* Attach:: Debugging an Already-Running Process
-* Kill Process:: Killing the Child Process
+* Compilation:: Compiling for Debugging
+* Starting:: Starting your Program
+* Arguments:: Your Program's Arguments
+* Environment:: Your Program's Environment
+* Working Directory:: Your Program's Working Directory
+* Input/Output:: Your Program's Input and Output
+* Attach:: Debugging an Already-Running Process
+* Kill Process:: Killing the Child Process
+* Process Information:: Additional Process Information
Stopping and Continuing
-* Breakpoints:: Breakpoints, Watchpoints, and Exceptions
-* Stepping and Continuing:: Resuming Execution
-* Signals:: Signals
+* 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::
+* 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
+* 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
+* 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
+* Expressions:: Expressions
+* Variables:: Program Variables
+* Arrays:: Artificial Arrays
+* Output formats:: Output formats
+* Memory:: Examining Memory
+* Auto Display:: Automatic Display
+* Print Settings:: Print Settings
+* Value History:: Value History
+* Convenience Vars:: Convenience Variables
+* Registers:: Registers
+* Floating Point Hardware:: Floating Point Hardware
+
+Using GDB with Different Languages
+
+* Setting:: Switching between source languages
+* Show:: Displaying the language
+* Checks:: Type and Range checks
+* Support:: Supported languages
+
+Switching between source languages
+
+* Manually:: Setting the working language manually
+* Automatically:: Having GDB infer the source language
+
+Type and range Checking
+
+* Type Checking:: An overview of type checking
+* Range Checking:: An overview of range checking
+
+Supported Languages
+
+* C:: C and C++
+* Modula-2:: Modula-2
+
+C and C++
+
+* C Operators:: C and C++ Operators
+* C Constants:: C and C++ Constants
+* Cplusplus expressions:: C++ Expressions
+* C Defaults:: Default settings for C and C++
+* C Checks:: C and C++ Type and Range Checks
+* Debugging C:: _GDBN__ and C
+* Debugging C plus plus:: Special features for C++
+
+Modula-2
+
+* M2 Operators:: Built-in operators
+* Built-In Func/Proc:: Built-in Functions and Procedures
+* M2 Constants:: Modula-2 Constants
+* M2 Defaults:: Default settings for Modula-2
+* Deviations:: Deviations from standard Modula-2
+* M2 Checks:: Modula-2 Type and Range Checks
+* M2 Scope:: The scope operators @code{::} and @code{.}
+* GDB/M2:: GDB and Modula-2
Altering Execution
-* Assignment:: Assignment to Variables
-* Jumping:: Continuing at a Different Address
-* Signaling:: Giving the Program a Signal
-* Returning:: Returning from a Function
-* Calling:: Calling your Program's Functions
+* Assignment:: Assignment to Variables
+* Jumping:: Continuing at a Different Address
+* Signaling:: Giving your program a Signal
+* Returning:: Returning from a Function
+* Calling:: Calling your Program's Functions
+* Patching:: Patching your Program
_GDBN__'s Files
-* Files:: Commands to Specify Files
-* Symbol Errors:: Errors Reading Symbol Files
+* Files:: Commands to Specify Files
+* Symbol Errors:: Errors Reading Symbol Files
-Specifying a Debugging Target
+Specifying a Debugging Target
-* Active Targets:: Active Targets
-* Target Commands:: Commands for Managing Targets
-* Remote:: Remote Debugging
+* Active Targets:: Active Targets
+* Target Commands:: Commands for Managing Targets
+* Remote:: Remote Debugging
Remote Debugging
-* i960-Nindy Remote::
-* EB29K Remote::
-* VxWorks Remote::
+* 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
+* 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
+* 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
+* 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
+* 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
+* 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
+* Bug Criteria:: Have You Found a Bug?
+* Bug Reporting:: How to Report Bugs
+
+Installing GDB
+
+* Separate Objdir:: Compiling _GDBN__ in another directory
+* Config Names:: Specifying names for hosts and targets
+* configure Options:: Summary of options for configure
@end menu
@node Summary, New Features, Top, Top
The purpose of a debugger such as _GDBN__ is to allow you to see what is
going on ``inside'' another program while it executes---or what another
-program was doing at the moment it crashed.
+program was doing at the moment it crashed.
_GDBN__ can do four main kinds of things (plus other things in support of
these) to help you catch bugs in the act:
effects of one bug and go on to learn about another.
@end itemize
-_GDBN__ can be used to debug programs written in C and C++. Pascal support
-is being implemented, and Fortran support will be added when a GNU
-Fortran compiler is ready.
+You can use _GDBN__ to debug programs written in C, C++, and Modula-2.
+Fortran support will be added when a GNU Fortran compiler is ready.
@menu
-* Free Software:: Free Software
-* Contributors:: Contributors to GDB
+* Free Software:: Free Software
+* Contributors:: Contributors to GDB
@end menu
@node Free Software, Contributors, Summary, Summary
@unnumberedsec Free Software
-_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
+
+_GDBN__ is @dfn{free software}, protected by the GNU General Public License
+(GPL). The GPL gives you the freedom to copy or adapt a licensed
program---but every person getting a copy also gets with it the
freedom to modify that copy (which means that they must get access to
the source code), and the freedom to distribute further copies.
Free Software Foundation uses the GPL to preserve these freedoms.
Fundamentally, the General Public License is a license which says that
-you have these freedoms and that you can't take these freedoms away
+you have these freedoms and that you cannot take these freedoms away
from anyone else.
-@c FIXME: (passim) go through all xrefs, expanding to use text headings
-For full details, @pxref{Copying}.
+For full details, @pxref{Copying, ,GNU GENERAL PUBLIC LICENSE}.
+
@node Contributors, , Free Software, Summary
@unnumberedsec Contributors to GDB
@end quotation
So that they may not regard their long labor as thankless, we
-particularly thank those who shepherded GDB through major releases:
-John Gilmore (release 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,
+particularly thank those who shepherded GDB through major releases: Stu
+Grossman and John Gilmore (releases 4.6, 4.5, 4.4), John Gilmore
+(releases 4.3, 4.2, 4.1, 4.0, and 3.9); Jim Kingdon (releases 3.5, 3.4,
+3.3); and Randy Smith (releases 3.2, 3.1, 3.0). As major maintainer of
+GDB for some period, each contributed significantly to the structure,
stability, and capabilities of the entire debugger.
Richard Stallman, assisted at various times by Pete TerMaat, Chris
Clark wrote the GNU C++ demangler. Early work on C++ was by Peter
TerMaat (who also did much general update work leading to release 3.0).
-GDB 4.0 uses the BFD subroutine library to examine multiple
-object-file formats; BFD was a joint project of V. Gumby
+GDB 4 uses the BFD subroutine library to examine multiple
+object-file formats; BFD was a joint project of David V.
Henkel-Wallace, Rich Pixley, Steve Chamberlain, and John Gilmore.
David Johnson wrote the original COFF support; Pace Willison did
contributed Intel 386 support. Jay Vosburgh contributed Symmetry
support.
-Rich Schaefer helped with support of SunOS shared libraries.
+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.
Brian Fox is the author of the readline libraries providing
command-line editing and command history.
+Andrew Beers of SUNY Buffalo wrote the language-switching code and
+the Modula-2 support, and contributed the Languages chapter of this
+manual.
+
+Fred Fish wrote most of the support for Unix System Vr4, and enhanced
+the command-completion support to cover C++ overloaded symbols.
+
@node New Features, Sample Session, Summary, Top
-@unnumbered New Features since _GDBN__ version 3.5
+@unnumbered New Features since GDB version 3.5
@table @emph
@item Targets
Using the new command @code{target}, you can select at runtime whether
you are debugging local files, local processes, standalone systems over
-a serial port, realtime systems over a TCP/IP connection, etc.
-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.
+a serial port, realtime systems over a TCP/IP connection, etc. The
+command @code{load} can download programs into a remote system. Serial
+stubs are available for Motorola 680x0 and Intel 80386 remote systems;
+GDB also supports debugging realtime processes running under
+VxWorks, using SunRPC Remote Procedure Calls over TCP/IP to talk to a
+debugger stub on the target system. Internally, GDB now uses a
+function vector to mediate access to different targets; if you need to
+add your own support for a remote protocol, this makes it much easier.
@item Watchpoints
-_GDBN__ now sports watchpoints as well as breakpoints. You can use a
+GDB now sports watchpoints as well as breakpoints. You can use a
watchpoint to stop execution whenever the value of an expression
changes, without having to predict a particular place in your program
where this may happen.
+@item Wide Output
+Commands that issue wide output now insert newlines at places designed
+to make the output more readable.
+
@item Object Code Formats
-_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 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
+GDB uses a new library called the Binary File Descriptor (BFD)
+Library to permit it to switch dynamically, without reconfiguration or
+recompilation, between different object-file formats. Formats currently
+supported are COFF, a.out, and the Intel 960 b.out; files may be read as
+.o's, archive libraries, or core dumps. BFD is available as a
+subroutine library so that other programs may take advantage of it, and
+the other GNU binary utilities are being converted to use it.
+
+@item Configuration and Ports
Compile-time configuration (to select a particular architecture and
operating system) is much easier. The script @code{configure} now
-handles specification of separate host and target configurations.
+allows you to configure GDB as either a native debugger or a
+cross-debugger. @xref{Installing GDB}, for details on how to
+configure.
@item Interaction
-The user interface to _GDBN__'s control variables has been simplified
+The user interface to GDB's control variables has been simplified
and consolidated in two commands, @code{set} and @code{show}. Output
lines are now broken at readable places, rather than overflowing onto
the next line. You can suppress output of machine-level addresses,
displaying only source language information.
-
-@item Source Language
-_GDBN__ now has 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.
+@item C++
+GDB now supports C++ multiple inheritance (if used with a GCC
+version 2 compiler), and also has limited support for C++ exception
+handling, with the commands @code{catch} and @code{info catch}: GDB
+can break when an exception is raised, before the stack is peeled back
+to the exception handler's context.
+
+@item Modula-2
+GDB now has preliminary support for the GNU Modula-2 compiler,
+currently under development at the State University of New York at
+Buffalo. Coordinated development of both GDB and the GNU Modula-2
+compiler will continue into 1992. Other Modula-2 compilers are
+currently not supported, and attempting to debug programs compiled with
+them will likely result in an error as the symbol table of the
+executable is read in.
@item Command Rationalization
-Many _GDBN__ commands have been renamed to make them easier to remember
+Many GDB commands have been renamed to make them easier to remember
and use. In particular, the subcommands of @code{info} and
@code{show}/@code{set} are grouped to make the former refer to the state
-of your program, and the latter refer to the state of _GDBN__ itself.
+of your program, and the latter refer to the state of GDB itself.
@xref{Renamed Commands}, for details on what commands were renamed.
-@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.
-
@item Shared Libraries
-_GDBN__ 4.0 supports SunOS shared libraries.
+GDB 4 can debug programs and core files that use SunOS, SVR4, or IBM RS/6000
+shared libraries.
+
+@item Reference Card
+GDB 4 has a reference card. @xref{Formatting Documentation,,Formatting
+the Documentation}, for instructions to print it.
@item Work in Progress
Kernel debugging for BSD and Mach systems; Tahoe and HPPA architecture
support.
-
@end table
@node Sample Session, Invocation, New Features, Top
debugger. This chapter illustrates these commands.
@iftex
-In this sample session, we emphasize user input like this: @i{input},
+In this sample session, we emphasize user input like this: @b{input},
to make it easier to pick out from the surrounding output.
@end iftex
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
+then use the @code{m4} built-in @code{defn} to define @code{bar} as the
same thing. However, when we change the open quote string to
@code{<QUOTE>} and the close quote string to @code{<UNQUOTE>}, the same
procedure fails to define a new synonym @code{baz}:
@smallexample
-$ @i{cd gnu/m4}
-$ @i{./m4}
-@i{define(foo,0000)}
+$ @b{cd gnu/m4}
+$ @b{./m4}
+@b{define(foo,0000)}
-@i{foo}
+@b{foo}
0000
-@i{define(bar,defn(`foo'))}
+@b{define(bar,defn(`foo'))}
-@i{bar}
+@b{bar}
0000
-@i{changequote(<QUOTE>,<UNQUOTE>)}
+@b{changequote(<QUOTE>,<UNQUOTE>)}
-@i{define(baz,defn(<QUOTE>foo<UNQUOTE>))}
-@i{baz}
-@i{C-d}
+@b{define(baz,defn(<QUOTE>foo<UNQUOTE>))}
+@b{baz}
+@b{C-d}
m4: End of input: 0: fatal error: EOF in string
@end smallexample
Let's use _GDBN__ to try to see what's going on.
@smallexample
-$ @i{_GDBP__ m4}
-Reading symbol data from m4...done.
-(_GDBP__)
+$ @b{_GDBP__ m4}
+@c FIXME: this falsifies the exact text played out, to permit smallbook
+@c FIXME... format to come out better.
+GDB is free software and you are welcome to distribute copies
+ of it under certain conditions; type "show copying" to see
+ the conditions.
+There is absolutely no warranty for GDB; type "show warranty"
+for details.
+GDB _GDB_VN__, Copyright 1992 Free Software Foundation, Inc...
+(_GDBP__)
@end smallexample
@noindent
-_GDBN__ reads only enough symbol data to know where to find the rest
-when needed; as a result, the first prompt comes up very quickly. We
-then tell _GDBN__ to use a narrower display width than usual, so
-that examples will fit in this manual.
+_GDBN__ reads only enough symbol data to know where to find the rest when
+needed; as a result, the first prompt comes up very quickly. We now
+tell _GDBN__ to use a narrower display width than usual, so that examples
+will fit in this manual.
@smallexample
-(_GDBP__) @i{set width 70}
+(_GDBP__) @b{set width 70}
@end smallexample
-@noindent
-Let's see how the @code{m4} builtin @code{changequote} works.
+@noindent
+Let's see how the @code{m4} built-in @code{changequote} works.
Having looked at the source, we know the relevant subroutine is
@code{m4_changequote}, so we set a breakpoint there with _GDBN__'s
@code{break} command.
@smallexample
-(_GDBP__) @i{break m4_changequote}
+(_GDBP__) @b{break m4_changequote}
Breakpoint 1 at 0x62f4: file builtin.c, line 879.
@end smallexample
subroutine, the program runs as usual:
@smallexample
-(_GDBP__) @i{run}
-Starting program: /work/Editorial/gdb/gnu/m4/m4
-@i{define(foo,0000)}
+(_GDBP__) @b{run}
+Starting program: /work/Editorial/gdb/gnu/m4/m4
+@b{define(foo,0000)}
-@i{foo}
+@b{foo}
0000
@end smallexample
context where it stops.
@smallexample
-@i{changequote(<QUOTE>,<UNQUOTE>)}
+@b{changequote(<QUOTE>,<UNQUOTE>)}
-Breakpoint 1, m4_changequote (argc=3, argv=0x33c70) at builtin.c:879
-879 if (bad_argc(TOKEN_DATA_TEXT(argv[0]), argc, 1, 3))
+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
the next line of the current function.
@smallexample
-(_GDBP__) @i{n}
-882 set_quotes((argc >= 2) ? TOKEN_DATA_TEXT(argv[1]) : nil,
+(_GDBP__) @b{n}
+882 set_quotes((argc >= 2) ? TOKEN_DATA_TEXT(argv[1])\
+ : nil,
@end smallexample
@noindent
@code{set_quotes} looks like a promising subroutine. We can go into it
by using the command @code{s} (@code{step}) instead of @code{next}.
@code{step} goes to the next line to be executed in @emph{any}
-subroutine, so it steps into @code{set_quotes}.
+subroutine, so it steps into @code{set_quotes}.
@smallexample
-(_GDBP__) @i{s}
+(_GDBP__) @b{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.
+The display that shows the subroutine where @code{m4} is now
+suspended (and its arguments) is called a stack frame display. It
+shows a summary of the stack. We can use the @code{backtrace}
+command (which can also be spelled @code{bt}), to see where we are
+in the stack as a whole: the @code{backtrace} command displays a
+stack frame for each active subroutine.
@smallexample
-(_GDBP__) @i{bt}
+(_GDBP__) @b{bt}
#0 set_quotes (lq=0x34c78 "<QUOTE>", rq=0x34c88 "<UNQUOTE>")
at input.c:530
-#1 0x6344 in m4_changequote (argc=3, argv=0x33c70) at builtin.c:882
+#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
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}
+(_GDBP__) @b{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}
+(_GDBP__) @b{s}
+0x3b80 535 lquote = (lq == nil || *lq == '\0') ? \
+def_lquote : xstrdup(lq);
+(_GDBP__) @b{n}
+536 rquote = (rq == nil || *rq == '\0') ? def_rquote\
+ : xstrdup(rq);
+(_GDBP__) @b{n}
538 len_lquote = strlen(rquote);
@end smallexample
(@code{print}) to see their values.
@smallexample
-(_GDBP__) @i{p lquote}
+(_GDBP__) @b{p lquote}
$1 = 0x35d40 "<QUOTE>"
-(_GDBP__) @i{p rquote}
+(_GDBP__) @b{p rquote}
$2 = 0x35d50 "<UNQUOTE>"
@end smallexample
surrounding the current line, with the @code{l} (@code{list}) command.
@smallexample
-(_GDBP__) @i{l}
+(_GDBP__) @b{l}
533 xfree(rquote);
-534
-535 lquote = (lq == nil || *lq == '\0') ? def_lquote : xstrdup\
-(lq);
-536 rquote = (rq == nil || *rq == '\0') ? def_rquote : xstrdup\
-(rq);
-537
+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
+541
542 void
@end smallexample
@code{len_rquote}, and then examine the values of those variables.
@smallexample
-(_GDBP__) @i{n}
+(_GDBP__) @b{n}
539 len_rquote = strlen(lquote);
-(_GDBP__) @i{n}
+(_GDBP__) @b{n}
540 @}
-(_GDBP__) @i{p len_lquote}
+(_GDBP__) @b{p len_lquote}
$3 = 9
-(_GDBP__) @i{p len_rquote}
+(_GDBP__) @b{p len_rquote}
$4 = 7
@end smallexample
@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.
+assignments.
@smallexample
-(_GDBP__) p len_lquote=strlen(lquote)
+(_GDBP__) @b{p len_lquote=strlen(lquote)}
$5 = 7
-(_GDBP__) p len_rquote=strlen(rquote)
+(_GDBP__) @b{p len_rquote=strlen(rquote)}
$6 = 9
@end smallexample
example that caused trouble initially:
@smallexample
-(_GDBP__) @i{c}
+(_GDBP__) @b{c}
Continuing.
-@i{define(baz,defn(<QUOTE>foo<UNQUOTE>))}
+@b{define(baz,defn(<QUOTE>foo<UNQUOTE>))}
baz
0000
lengths. We'll let @code{m4} exit by giving it an EOF as input.
@smallexample
-@i{C-d}
+@b{C-d}
Program exited normally.
@end smallexample
-@noindent
+@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}
+(_GDBP__) @b{quit}
_1__@end smallexample
@node Invocation, Commands, Sample Session, Top
@chapter Getting In and Out of _GDBN__
+This chapter discusses how to start _GDBN__, and how to get out of it.
+(The essentials: type @samp{_GDBP__} to start GDB, and type @kbd{quit}
+or @kbd{C-d} to exit.)
+
@menu
-* Starting _GDBN__:: Starting _GDBN__
-* Leaving _GDBN__:: Leaving _GDBN__
-* Shell Commands:: Shell Commands
+* Invoking _GDBN__:: Starting _GDBN__
+* Leaving _GDBN__:: Leaving _GDBN__
+* Shell Commands:: Shell Commands
@end menu
-@node Starting _GDBN__, Leaving _GDBN__, Invocation, Invocation
+@node Invoking _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.
+Start _GDBN__ with the shell command @code{_GDBP__}. Once it's running,
+_GDBN__ reads commands from the terminal until you tell it to exit.
+
+You can also run @code{_GDBP__} with a variety of arguments and options,
+to specify more of your debugging environment at the outset.
+
+The command-line options described here are designed
+to cover a variety of situations; in some environments, some of these
+options may effectively be unavailable.
+
+_if__(_H8__)
+For details on starting up _GDBP__ as a
+remote debugger attached to a Hitachi H8/300 board, see @ref{Hitachi
+H8/300 Remote,,_GDBN__ and the Hitachi H8/300}.
+_fi__(_H8__)
+
+The most usual way to start _GDBN__ is with one argument or two,
+specifying an executable program as the argument:
-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
+_GDBP__ @var{program}
@end example
+
@noindent
-You can also 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__ @var{program} @var{core}
+@end example
+
+You can, instead, specify a process ID as a second argument, if you want
+to debug a running process:
+
@example
-_GDBP__ program core
+_GDBP__ @var{program} 1234
@end example
+@noindent
+would attach _GDBN__ to process @code{1234} (unless you also have a file
+named @file{1234}; _GDBN__ does check for a core file first).
+
+Taking advantage of the second command-line argument requires a fairly
+complete operating system; when you use _GDBN__ as a remote debugger
+attached to a bare board, there may not be any notion of ``process'',
+and there is often no way to get a core dump.
+
@noindent
You can further control how _GDBN__ starts up by using command-line
-options. _GDBN__ itself can remind you of the options available:
+options. _GDBN__ itself can remind you of the options available.
+
+@noindent
+Type
+
@example
_GDBP__ -help
@end example
+
@noindent
-will display all available options and briefly describe their use
+to display all available options and briefly describe their use
(@samp{_GDBP__ -h} is a shorter equivalent).
All options and command line arguments you give are processed
in sequential order. The order makes a difference when the
-@samp{-x} option is used.
+@samp{-x} option is used.
@menu
-* File Options:: Choosing Files
-* Mode Options:: Choosing Modes
+* 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__
+@node File Options, Mode Options, Invoking _GDBN__, Invoking _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. 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.)
+When _GDBN__ starts, it reads any arguments other than options as
+specifying an executable file and core file (or process ID). This is
+the same as if the arguments were specified by the @samp{-se} and
+@samp{-c} options respectively. (_GDBN__ reads the first argument
+that does not have an associated option flag as equivalent to the
+@samp{-se} option followed by that argument; and the second argument
+that does not have an associated option flag, if any, as equivalent to
+the @samp{-c} option followed by that argument.)
+
+Many options have both long and short forms; both are shown in the
+following list. _GDBN__ also recognizes the long forms if you truncate
+them, so long as enough of the option is present to be unambiguous.
+(If you prefer, you can flag option arguments with @samp{--} rather
+than @samp{-}, though we illustrate the more usual convention.)
@table @code
@item -symbols=@var{file}
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 -directory=@var{directory}
@itemx -d @var{directory}
Add @var{directory} to the path to search for source files.
+
+@item -m
+@itemx -mapped
+@emph{Warning: this option depends on operating system facilities that are not
+supported on all systems.}@*
+If memory-mapped files are available on your system through the @code{mmap}
+system call, you can use this option
+to cause _GDBN__ to write the symbols from your
+program into a reusable file in the current directory. If the program you are debugging is
+called @file{/tmp/fred}, the mapped symbol file will be @file{./fred.syms}.
+Future _GDBN__ debugging sessions will notice the presence of this file,
+and will quickly map in symbol information from it, rather than reading
+the symbol table from the executable program.
+
+The @file{.syms} file is specific to the host machine on which _GDBN__ is run.
+It holds an exact image of _GDBN__'s internal symbol table. It cannot be
+shared across multiple host platforms.
+
+@item -r
+@itemx -readnow
+Read each symbol file's entire symbol table immediately, rather than
+the default, which is to read it incrementally as it is needed.
+This makes startup slower, but makes future operations faster.
@end table
+The @code{-mapped} and @code{-readnow} options are typically combined in order to
+build a @file{.syms} file that contains complete symbol information.
+A simple GDB invocation to do nothing but build a @file{.syms} file for future
+use is:
+
+@example
+ gdb -batch -nx -mapped -readnow programname
+@end example
+
_if__(!_GENERIC__)
-@node Mode Options, i960-Nindy Remote, File Options, Starting _GDBN__
+@node Mode Options, Mode Options, File Options, Invoking _GDBN__
_fi__(!_GENERIC__)
_if__(_GENERIC__)
-@node Mode Options, , File Options, Starting _GDBN__
-_fi__(_GENERIC__)
+@node Mode Options, , File Options, Invoking _GDBN__
+_fi__(_GENERIC__)
@subsection Choosing Modes
+You can run _GDBN__ in various alternative modes---for example, in
+batch mode or quiet mode.
+
@table @code
@item -nx
@itemx -n
Do not execute commands from any @file{_GDBINIT__} initialization files.
Normally, the commands in these files are executed after all the
-command options and arguments have been processed. @xref{Command
-Files}.
+command options and arguments have been processed.
+@xref{Command Files}.
@item -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 status @code{0} after processing all the command
files specified with @samp{-x} (and @file{_GDBINIT__}, if not inhibited).
Exit with nonzero status if an error occurs in executing the _GDBN__
-commands in the command files.
+commands in the command files.
Batch mode may be useful for running _GDBN__ as a filter, for example to
download and run a program on another computer; in order to make this
-more useful, the message
+more useful, the message
+
@example
Program exited normally.
@end example
+
@noindent
(which is ordinarily issued whenever a program running under _GDBN__ control
terminates) is not issued when running in batch mode.
-@item -cd @var{directory}
+@item -cd=@var{directory}
Run _GDBN__ using @var{directory} as its working directory,
instead of the current directory.
+_if__(_LUCID__)
+@item -context @var{authentication}
+When the Energize programming system starts up _GDBN__, it uses this
+option to trigger an alternate mode of interaction.
+@var{authentication} is a pair of numeric codes that identify _GDBN__
+as a client in the Energize environment. Avoid this option when you run
+_GDBN__ directly from the command line. See @ref{Energize,,Using
+_GDBN__ with Energize} for more discussion of using _GDBN__ with Energize.
+_fi__(_LUCID__)
+
@item -fullname
@itemx -f
Emacs sets this option when it runs _GDBN__ as a subprocess. It tells _GDBN__
to output the full file name and line number in a standard,
recognizable fashion each time a stack frame is displayed (which
-includes each time the program stops). This recognizable format looks
+includes each time your program stops). This recognizable format looks
like two @samp{\032} characters, followed by the file name, line number
and character position separated by colons, and a newline. The
Emacs-to-_GDBN__ interface program uses the two @samp{\032} characters as
Set the line speed (baud rate or bits per second) of any serial
interface used by _GDBN__ for remote debugging.
-@item -tty @var{device}
+@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.
+@c FIXME: kingdon thinks there is more to -tty. Investigate.
@end table
_if__(!_GENERIC__)
_include__(gdbinv-s.m4)
_fi__(!_GENERIC__)
-
-@node Leaving _GDBN__, Shell Commands, Starting _GDBN__, Invocation
+@node Leaving _GDBN__, Shell Commands, Invoking _GDBN__, Invocation
@section Leaving _GDBN__
@cindex exiting _GDBN__
+
@table @code
@item quit
@kindex quit
@kindex q
To exit _GDBN__, use the @code{quit} command (abbreviated @code{q}), or type
-an end-of-file character (usually @kbd{C-d}).
+an end-of-file character (usually @kbd{C-d}).
@end table
@cindex interrupt
character at any time because _GDBN__ does not allow it to take effect
until a time when it is safe.
-If you've been using _GDBN__ to control an attached process or device,
-you can release it with the @code{detach} command; @pxref{Attach}.
+If you have been using _GDBN__ to control an attached process or device, you
+can release it with the @code{detach} command; @pxref{Attach,
+,Debugging an Already-Running Process}..
@node 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
+debugging session, there is no need to leave or suspend _GDBN__; you can
just use the @code{shell} command.
@table @code
@end table
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__:
+You do not have to use the @code{shell} command for this purpose in _GDBN__:
@table @code
@item make @var{make-args}
@node Commands, Running, Invocation, Top
@chapter _GDBN__ Commands
+You can abbreviate a _GDBN__ command to the first few letters of the command
+name, if that abbreviation is unambiguous; and you can repeat certain
+_GDBN__ commands by typing just @key{RET}. You can also use the @key{TAB}
+key to get _GDBN__ to fill out the rest of a word in a command (or to
+show you the alternatives available, if there's more than one possibility).
+
@menu
-* Command Syntax:: Command Syntax
-* Help:: Getting Help
+* Command Syntax:: Command Syntax
+* Completion:: Command Completion
+* Help:: Getting Help
@end menu
-@node Command Syntax, Help, Commands, Commands
+@node Command Syntax, Completion, Commands, Commands
@section Command Syntax
+
A _GDBN__ command is a single line of input. There is no limit on how long
it can be. It starts with a command name, which is followed by arguments
whose meaning depends on the command name. For example, the command
names start with @code{s}. You can test abbreviations by using them as
arguments to the @code{help} command.
-@cindex repeating commands
+@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})
@key{RET}, construct new arguments rather than repeating
exactly as typed. This permits easy scanning of source or memory.
+_GDBN__ can also use @key{RET} in another way: to partition lengthy
+output, in a way similar to the common utility @code{more}
+(@pxref{Screen Size}). Since it is easy to press one @key{RET} too many
+in this situation, _GDBN__ disables command repetition after any command
+that generates this sort of display.
+
@kindex #
@cindex comment
A line of input starting with @kbd{#} is a comment; it does nothing.
-This is useful mainly in command files (@xref{Command Files}).
+This is useful mainly in command files (@pxref{Command Files}).
+
+@node Completion, Help, Command Syntax, Commands
+@section Command Completion
+
+@cindex completion
+@cindex word completion
+_GDBN__ can fill in the rest of a word in a command for you, if there's
+only one possibility; it can also show you what the valid possibilities
+are for the next word in a command, at any time. This works for _GDBN__
+commands, _GDBN__ subcommands, and the names of symbols in your program.
+
+Press the @key{TAB} key whenever you want _GDBN__ to fill out the rest
+of a word. If there's only one possibility, _GDBN__ will fill in the
+word, and wait for you to finish the command (or press @key{RET} to
+enter it). For example, if you type
+
+@example
+(_GDBP__) info bre@key{TAB}
+@end example
+
+@noindent
+_GDBN__ fills in the rest of the word @samp{breakpoints}, since that's
+the only @code{info} subcommand beginning with @samp{bre}:
+
+@example
+(_GDBP__) info breakpoints
+@end example
+
+@noindent
+You can either press @key{RET} at this point, to run the @code{info
+breakpoints} command, or backspace and enter something else, if
+@samp{breakpoints} doesn't look like the command you expected. (If you
+were sure you wanted @code{info breakpoints} in the first place, you
+might as well just type @key{RET} immediately after @samp{info bre},
+to exploit command abbreviations rather than command completion).
+
+If there is more than one possibility for the next word when you press
+@key{TAB}, _GDBN__ will sound a bell. You can either supply more
+characters and try again, or just press @key{TAB} a second time, and
+_GDBN__ will display all the possible completions for that word. For
+example, you might want to set a breakpoint on a subroutine whose name
+begins with @samp{mak}, but when you type @kbd{b mak@key{TAB}} _GDBN__
+just sounds the bell. Typing @key{TAB} again will display all the
+function names in your program that begin with those characters, for
+example:
+
+@example
+(_GDBP__) b mak@key{TAB}
+make_a_section_from_file make_environ
+make_abs_section make_function_type
+make_blockvector make_pointer_type
+make_cleanup make_reference_type
+make_command make_symbol_completion_list
+(GDBP__) b mak
+@end example
+
+@noindent
+After displaying the available possibilities, _GDBN__ copies your
+partial input (@samp{b mak} in the example) so you can finish the
+command.
+
+If you just want to see the list of alternatives in the first place, you
+can press @kbd{M-?} rather than pressing @key{TAB} twice. (@kbd{M-?}
+means @kbd{@key{META} ?}. If your keyboard doesn't have a Meta shift,
+you can type @key{ESC} followed by @kbd{?} instead.)
+
+@cindex quotes in commands
+@cindex completion of quoted strings
+Sometimes the string you need, while logically a ``word'', may contain
+parentheses or other characters that _GDBN__ normally excludes from its
+notion of a word. To permit word completion to work in this situation,
+you may enclose words in @code{'} (single quote marks) in _GDBN__ commands.
+
+The most likely situation where you might need this is in typing the
+name of a C++ function. This is because C++ allows function overloading
+(multiple definitions of the same function, distinguished by argument
+type). For example, you may need to distinguish whether you mean
+@samp{name(int)} or @samp{name(float)} when you want to set a
+breakpoint. To use the word-completion facilities in this situation,
+type a single quote @code{'} at the beginning of the function name.
+This alerts _GDBN__ that it may need to consider more information than
+usual when you press @key{TAB} or @kbd{M-?} to request word completion:
+
+@example
+(_GDBP__) b 'name(@key{M-?}
+name(int) name(float)
+(_GDBP__) b 'name
+@end example
-@node Help, , Command Syntax, Commands
+@node Help, , Completion, 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}.
+command @code{help}.
@table @code
@item help
@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:
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.
+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__)
+(_GDBP__)
@end smallexample
@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.
show -- Generic command for showing things set with "set"
info -- Generic command for printing status
-Type "help" followed by command name for full documentation.
+Type "help" followed by command name for full
+documentation.
Command name abbreviations are allowed if unambiguous.
-(_GDBP__)
+(_GDBP__)
@end smallexample
@item help @var{command}
With a command name as @code{help} argument, _GDBN__ will display a
-short paragraph on how to use that command.
+short paragraph on how to use that command.
@end table
In addition to @code{help}, you can use the _GDBN__ commands @code{info}
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.
+all the sub-commands. @xref{Index}.
@c @group
@table @code
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}).
+registers}), or the breakpoints you have set (@code{info breakpoints}).
You can get a complete list of the @code{info} sub-commands with
@w{@code{help info}}.
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}.
+which is currently in use with @code{show radix}.
@kindex info set
To display all the settable parameters and their current
@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.
+information in _GDBN__ bug-reports. If multiple versions of _GDBN__ are in
+use at your site, you may occasionally want to make sure what version
+of _GDBN__ you are running; as _GDBN__ evolves, new commands are introduced,
+and old ones may wither away. The version number is also announced
+when you start _GDBN__ with no arguments.
@kindex show copying
@item show copying
@node Running, Stopping, Commands, Top
@chapter Running Programs Under _GDBN__
+To debug a program, you must run it under _GDBN__.
+
@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
+* Compilation:: Compiling for Debugging
+* Starting:: Starting your Program
+* Arguments:: Your Program's Arguments
+* Environment:: Your Program's Environment
+* Working Directory:: Your Program's Working Directory
+* Input/Output:: Your Program's Input and Output
+* Attach:: Debugging an Already-Running Process
+* Kill Process:: Killing the Child Process
+* Process Information:: Additional Process Information
@end menu
@node Compilation, Starting, Running, Running
options together. Using those compilers, you cannot generate optimized
executables containing debugging information.
-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.
+_GCC__, the GNU C compiler, supports @samp{-g} with or without
+@samp{-O}, making it possible to debug optimized code. We recommend
+that you @emph{always} use @samp{-g} whenever you compile a program.
+You may think your program is correct, but there is no sense in pushing
+your luck.
+
+@cindex optimized code, debugging
+@cindex debugging optimized code
+When you debug a program compiled with @samp{-g -O}, remember that the
+optimizer is rearranging your code; the debugger will show you what's
+really there. Don't be too surprised when the execution path doesn't
+exactly match your source file! An extreme example: if you define a
+variable, but never use it, _GDBN__ will never see that
+variable---because the compiler optimizes it out of existence.
Some things do not work as well with @samp{-g -O} as with just
@samp{-g}, particularly on machines with instruction scheduling. If in
please report it as a bug (including a test case!).
Older versions of the GNU C compiler permitted a variant option
-@samp{-gg} for debugging information. _GDBN__ no longer supports this
+@w{@samp{-gg}} for debugging information. _GDBN__ no longer supports this
format; if your GNU C compiler has this option, do not use it.
@ignore
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
+confused reading your program's symbol table. No error message will be
given, but _GDBN__ may behave strangely. The reason for this problem is a
deficiency in the Unix archive file format, which cannot represent file
names longer than 15 characters.
@code{ar} dated more recently than August 1989.
@end ignore
-
@node Starting, Arguments, Compilation, Running
@section Starting your Program
@cindex starting
@cindex running
+
@table @code
@item run
@itemx r
@kindex run
-Use the @code{run} command to start your program under _GDBN__. You
-must first specify the program name
-_if__(_VXWORKS__)
+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
+with an argument to
+_GDBN__ (@pxref{Invocation, ,Getting In and Out of _GDBN__}), or by using the
+@code{file} or @code{exec-file} command (@pxref{Files, ,Commands to
+Specify Files}).
+
@end table
-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.
+If you are running your program in an execution environment that
+supports processes, @code{run} creates an inferior process and makes
+that process run your program. (In environments without processes,
+@code{run} jumps to the start of your program.)
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
+information, which you must do @emph{before} starting your program. (You
+can change it after starting your program, but such changes will only affect
+your program the next time you start it.) This information may be
divided into four categories:
@table @asis
-@item The @i{arguments.}
-You specify the arguments to give your program as the arguments of the
+@item The @emph{arguments.}
+Specify the arguments to give your program as the arguments of the
@code{run} command. If a shell is available on your target, the shell
is used to pass the arguments, so that you may use normal conventions
-(such as wildcard expansion or variable substitution) in
-describing the arguments. In Unix systems, you can control which shell
-is used with the @code{SHELL} environment variable. @xref{Arguments}.@refill
+(such as wildcard expansion or variable substitution) in describing
+the arguments. In Unix systems, you can control which shell is used
+with the @code{SHELL} environment variable. @xref{Arguments, ,Your
+Program's Arguments}.
-@item The @i{environment.}
+@item The @emph{environment.}
Your program normally inherits its environment from _GDBN__, but you can
use the _GDBN__ commands @code{set environment} and @code{unset
environment} to change parts of the environment that will be given to
-the program. @xref{Environment}.@refill
+your program. @xref{Environment, ,Your Program's Environment}.
-@item The @i{working directory.}
+@item The @emph{working directory.}
Your program inherits its working directory from _GDBN__. You can set
_GDBN__'s working directory with the @code{cd} command in _GDBN__.
-@xref{Working Directory}.
+@xref{Working Directory, ,Your Program's Working Directory}.
-@item The @i{standard input and output.}
+@item The @emph{standard input and output.}
Your program normally uses the same device for standard input and
standard output as _GDBN__ is using. You can redirect input and output
in the @code{run} command line, or you can use the @code{tty} command to
set a different device for your program.
-@xref{Input/Output}.
+@xref{Input/Output, ,Your Program's Input and Output}.
+
+@cindex pipes
+@emph{Warning:} While input and output redirection work, you cannot use
+pipes to pass the output of the program you are debugging to another
+program; if you attempt this, _GDBN__ is likely to wind up debugging the
+wrong program.
@end table
+@c FIXME: Rewrite following paragraph, especially its third sentence.
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.
+immediately. @xref{Stopping, ,Stopping and Continuing}, for
+discussion of how to arrange for your program to stop. Once your
+program has been started by the @code{run} command (and then stopped),
+you may evaluate expressions that involve calls to functions in your
+program, using the @code{print} or @code{call} commands. @xref{Data,
+,Examining Data}.
+
+If the modification time of your symbol file has changed since the
+last time _GDBN__ read its symbols, _GDBN__ will discard its symbol table and
+re-read it. When it does this, _GDBN__ tries to retain your current
+breakpoints.
@node Arguments, Environment, Starting, Running
@section Your Program's Arguments
@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.
+characters and performs redirection of I/O, and thence to your program.
_GDBN__ uses the shell indicated by your environment variable
@code{SHELL} if it exists; otherwise, _GDBN__ uses @code{/bin/sh}.
@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,
+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.
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
+debugging, it can be useful to try running your program with a modified
environment without having to start _GDBN__ over again.
@table @code
(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.
+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 'path' is explicitly nonrepeatable, but RMS points out it is silly to
@c document that, since repeating it would be a no-op.
@item show paths
@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},
+your program when it starts. If you do not supply @var{varname},
print the names and values of all environment variables to be given to
your program. You can abbreviate @code{environment} as @code{env}.
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 "any string" here does not include leading, trailing
@c blanks. Gnu asks: does anyone care?
For example, this command:
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.
+rather than assigning it an empty value.
@end table
@node Working Directory, Input/Output, Environment, Running
directory in _GDBN__ with the @code{cd} command.
The _GDBN__ working directory also serves as a default for the commands
-that specify files for _GDBN__ to operate on. @xref{Files}.
+that specify files for _GDBN__ to operate on. @xref{Files, ,Commands to
+Specify Files}.
@table @code
@item cd @var{directory}
program is using.
@end table
-You can redirect the program's input and/or output using shell
+You can redirect your program's input and/or output using shell
redirection with the @code{run} command. For example,
_0__@example
_1__@end example
@noindent
-starts the program, diverting its output to the file @file{outfile}.
+starts your 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
+Another way to specify where your program should do input and output is
with the @code{tty} command. This command accepts a file name as
argument, and causes this file to be the default for future @code{run}
commands. It also resets the controlling terminal for the child
(@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.
+shell command.
@code{attach} will not repeat if you press @key{RET} a second time after
executing the command.
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}.
+@xref{Files, ,Commands to Specify Files}.
The first thing _GDBN__ does after arranging to debug the specified
process is to stop it. You can examine and modify an attached process
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}).
+(@pxref{Messages/Warnings, ,Optional Warnings and Messages}).
-@node Kill Process, , Attach, Running
+@node Kill Process, Process Information, Attach, Running
@c @group
@section Killing the Child Process
is running.
@c @end group
-On some operating systems, a program can't be executed outside _GDBN__
+On some operating systems, a program cannot be executed outside _GDBN__
while you have breakpoints set on it inside _GDBN__. You can use the
-@code{kill} command in this situation to permit running the program
+@code{kill} command in this situation to permit running your program
outside the debugger.
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
+relink your program, since on many systems it is impossible to modify an
executable file while it is running in a process. In this case, when you
next type @code{run}, _GDBN__ will notice that the file has changed, and
will re-read the symbol table (while trying to preserve your current
breakpoint settings).
+@node Process Information, , Kill Process, Running
+@section Additional Process Information
+
+@kindex /proc
+@cindex process image
+Some operating systems provide a facility called @samp{/proc} that can
+be used to examine the image of a running process using file-system
+subroutines. If _GDBN__ is configured for an operating system with this
+facility, the command @code{info proc} is available to report on several
+kinds of information about the process running your program.
+
+@table @code
+@item info proc
+@kindex info proc
+Summarize available information about the process.
+
+@item info proc mappings
+@kindex info proc mappings
+Report on the address ranges accessible in the program, with information
+on whether your program may read, write, or execute each range.
+
+@item info proc times
+@kindex info proc times
+Starting time, user CPU time, and system CPU time for your program and
+its children.
+
+@item info proc id
+@kindex info proc id
+Report on the process ID's related to your program: its own process id,
+the id of its parent, the process group id, and the session id.
+
+@item info proc status
+@kindex info proc status
+General information on the state of the process. If the process is
+stopped, this report includes the reason for stopping, and any signal
+received.
+
+@item info proc all
+Show all the above information about the process.
+@end table
+
@node Stopping, Stack, Running, Top
@chapter Stopping and Continuing
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
+program before it terminates; or so that, if your program runs into
trouble, you can investigate and find out why.
Inside _GDBN__, your program may stop for any of several reasons, such
@end table
@menu
-* Breakpoints:: Breakpoints, Watchpoints, and Exceptions
-* Stepping and Continuing:: Resuming Execution
-* Signals:: Signals
+* Breakpoints:: Breakpoints, Watchpoints, and Exceptions
+* Continuing and Stepping:: Resuming Execution
+* Signals:: Signals
@end menu
-@node Breakpoints, Stepping and Continuing, Stopping, Stopping
+@node Breakpoints, Continuing and Stepping, Stopping, Stopping
@section Breakpoints, Watchpoints, and Exceptions
@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.
+conditions to control in finer detail whether your program will stop.
You can set breakpoints with the @code{break} command and its variants
-(@pxref{Set Breaks}), 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}).
+(@pxref{Set Breaks, ,Setting Breakpoints}), to specify the place where
+your program should stop by line number, function name or exact address
+in the program. In languages with exception handling (such as GNU
+C++), you can also set breakpoints where an exception is raised
+(@pxref{Exception Handling, ,Breakpoints and Exceptions}).
@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.
+@cindex memory tracing
+@cindex breakpoint on memory address
+@cindex breakpoint on variable modification
+A @dfn{watchpoint} is a special breakpoint that stops your program
+when the value of an expression changes. You must use a different
+command to set watchpoints (@pxref{Set Watchpoints, ,Setting
+Watchpoints}), but aside from that, you can manage a watchpoint like
+any other breakpoint: you enable, disable, and delete both breakpoints
+and watchpoints using the same commands.
+
+@cindex breakpoint numbers
+@cindex numbers for breakpoints
+_GDBN__ assigns a number to each breakpoint or watchpoint when you
+create it; these numbers are successive integers starting with one. In
+many of the commands for controlling various features of breakpoints you
+use the breakpoint number to say which breakpoint you want to change.
+Each breakpoint may be @dfn{enabled} or @dfn{disabled}; if disabled, it has
+no effect on your program until you enable it again.
@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::
+* 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
@node Set Breaks, Set Watchpoints, Breakpoints, Breakpoints
@subsection Setting Breakpoints
+@c FIXME LMB what does GDB do if no code on line of breakpt?
+@c consider in particular declaration with/without initialization.
+@c
+@c FIXME 2 is there stuff on this already? break at fun start, already init?
+
@kindex break
@kindex b
-Breakpoints are set with the @code{break} command (abbreviated @code{b}).
+@kindex $bpnum
+@cindex latest breakpoint
+Breakpoints are set with the @code{break} command (abbreviated
+@code{b}). The debugger convenience variable @samp{$bpnum} records the
+number of the beakpoint you've set most recently; see @ref{Convenience
+Vars,, Convenience Variables}, for a discussion of what you can do with
+convenience variables.
You have several ways to say where the breakpoint should go.
@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
+breakpoint will stop your program just before it executes any of the
code on that line.
@item break @var{filename}:@var{linenum}
@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
+breakpoints in parts of your program which do not have debugging
information or source files.
@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.
+When called without any arguments, @code{break} sets a breakpoint at
+the next instruction to be executed in the selected stack frame
+(@pxref{Stack, ,Examining the Stack}). In any selected frame but the
+innermost, this will cause your program to stop as soon as control
+returns to that frame. This is similar to the effect of a
+@code{finish} command in the frame inside the selected frame---except
+that @code{finish} does not leave an active breakpoint. If you use
+@code{break} without an argument in the innermost frame, _GDBN__ will stop
+the next time it reaches the current location; this may be useful
+inside loops.
_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.
+existed when your program stopped.
@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.
+value is nonzero---that is, if @var{cond} evaluates as true.
+@samp{@dots{}} stands for one of the possible arguments described
+above (or no argument) specifying where to break. @xref{Conditions,
+,Break Conditions}, for more information on breakpoint conditions.
@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}.
+way, but the breakpoint is automatically disabled after the first time your
+program stops there. @xref{Disabling, ,Disabling Breakpoints}.
@item rbreak @var{regex}
@kindex rbreak
@cindex regular expression
-@c FIXME: 2nd sentence below C++ only?
+@c FIXME what kind of regexp?
Set breakpoints on all functions matching the regular expression
-@var{regex}. This is useful for setting breakpoints on overloaded
-functions that are not members of any special classes. This command
+@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
-@kindex $_
+@cindex @code{$_} 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{$_} and the default examining-address for the @code{x}
-command are set to the address of the last breakpoint listed
-(@pxref{Memory}). The equivalent command for watchpoints is @code{info
-watch}. @end table
-
-_GDBN__ allows you to set any number of breakpoints at the same place in the
-program. There is nothing silly or meaningless about this. When the
-breakpoints are conditional, this is even useful (@pxref{Conditions}).
+@itemx info break @r{[}@var{n}@r{]}
+@itemx info watchpoints @r{[}@var{n}@r{]}
+Print a table of all breakpoints and watchpoints set and not
+deleted, with the following columns for each breakpoint:
+
+@table @emph
+@item Breakpoint Numbers
+@item Type
+Breakpoint or watchpoint.
+@item Disposition
+Whether the breakpoint is marked to be disabled or deleted when hit.
+@item Enabled or Disabled
+Enabled breakpoints are marked with @samp{y}. @samp{n} marks breakpoints
+that are not enabled.
+@item Address
+Where the breakpoint is in your program, as a memory address
+@item What
+Where the breakpoint is in the source for your program, as a file and
+line number.
+@end table
+
+@noindent
+Breakpoint commands, if any, are listed after the line for the
+corresponding breakpoint.
+
+@noindent
+@code{info break} with a breakpoint
+number @var{n} as argument lists only that breakpoint. The
+convenience variable @code{$_} and the default examining-address for
+the @code{x} command are set to the address of the last breakpoint
+listed (@pxref{Memory, ,Examining Memory}).
+@end table
+
+_GDBN__ allows you to set any number of breakpoints at the same place in
+your program. There is nothing silly or meaningless about this. When
+the breakpoints are conditional, this is even useful
+(@pxref{Conditions, ,Break Conditions}).
+
+@cindex negative breakpoint numbers
+@cindex internal _GDBN__ breakpoints
+_GDBN__ itself sometimes sets breakpoints in your program for special
+purposes, such as proper handling of @code{longjmp} (in C programs).
+These internal breakpoints are assigned negative numbers, starting with
+@code{-1}; @samp{info breakpoints} does not display them, but the
+similar command @samp{info all-breakpoints} does.
+
+@table @code
+@kindex all-breakpoints
+@item info all-breakpoints
+Using the same format as @samp{info breakpoints}, display both the
+breakpoints you've set explicitly, and those _GDBN__ is using for
+internal purposes. Internal breakpoints are shown with negative
+breakpoint numbers. The type column identifies what kind of breakpoint
+is shown:
+
+@table @code
+@item breakpoint
+Normal, explicitly set breakpoint.
+
+@item watchpoint
+Normal, explicitly set watchpoint.
+
+@item longjmp
+Internal breakpoint, used to handle correctly stepping through
+@code{longjmp} calls.
+
+@item longjmp resume
+Internal breakpoint at the target of a @code{longjmp}.
+
+@item until
+Temporary internal breakpoint used by the _GDBN__ @code{until} command.
+
+@item finish
+Temporary internal breakpoint used by the _GDBN__ @code{finish} command.
+@end table
+
+@end table
+
@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
+expression changes, without having to predict a particular place
where this may happen.
Watchpoints currently execute two orders of magnitude more slowly than
releases of _GDBN__ will use such hardware if it is available.
@table @code
-@kindex watch
+@kindex watch
@item watch @var{expr}
Set a watchpoint for an expression.
@kindex info watchpoints
@item info watchpoints
-This command prints a list of watchpoints; it is otherwise similar to
-@code{info break}.
+This command prints a list of watchpoints and breakpoints; it is the
+same as @code{info break}.
@end table
@node Exception Handling, Delete Breaks, Set Watchpoints, Breakpoints
@subsection Breakpoints and Exceptions
@cindex exception handlers
-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
+Some languages, such as GNU C++, implement exception handling. You can
+use _GDBN__ to examine what caused your program to raise an exception,
+and to list the exceptions your program is prepared to handle at a
given point in time.
@table @code
to catch.
@end table
-You can use @code{info catch} to list active exception handlers;
-@pxref{Frame Info}.
+You can use @code{info catch} to list active exception handlers.
+@xref{Frame Info, ,Information About a Frame}.
There are currently some limitations to exception handling in _GDBN__.
These will be corrected in a future release.
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
+returns control to you and cause your program to simply continue
running until it hits a breakpoint, catches a signal that _GDBN__ is
listening for, or exits.
@item
@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
+if you need to know exactly where an exception is raised, it is better to
stop @emph{before} the exception handler is called, since that way you
can see the stack before any unwinding takes place. If you set a
breakpoint in an exception handler instead, it may not be easy to find
out where the exception was raised.
To stop just before an exception handler is called, you need some
-knowledge of the implementation. In the case of GNU C++ exceptions are
+knowledge of the implementation. In the case of GNU C++, exceptions are
raised by calling a library function named @code{__raise_exception}
which has the following ANSI C interface:
@example
- /* ADDR is where the exception identifier is stored.
+ /* @var{addr} is where the exception identifier is stored.
ID is the exception identifier. */
void __raise_exception (void **@var{addr}, void *@var{id});
@end example
@noindent
To make the debugger catch all exceptions before any stack
unwinding takes place, set a breakpoint on @code{__raise_exception}
-(@pxref{Breakpoints}).
+(@pxref{Breakpoints, ,Breakpoints Watchpoints and Exceptions}).
-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.
+With a conditional breakpoint (@pxref{Conditions, ,Break Conditions})
+that depends on the value of @var{id}, you can stop your program when
+a specific exception is raised. You can use multiple conditional
+breakpoints to stop your program when any of a number of exceptions are
+raised.
@node Delete Breaks, Disabling, Exception Handling, Breakpoints
@subsection Deleting Breakpoints
@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
+has done its job and you no longer want your program to stop there. This
is called @dfn{deleting} the breakpoint. A breakpoint that has been
deleted no longer exists; it is forgotten.
With the @code{clear} command you can delete breakpoints according to
-where they are in the program. With the @code{delete} command you can
+where they are in your program. With the @code{delete} command you can
delete individual breakpoints or watchpoints by specifying their
breakpoint numbers.
@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.
+selected stack frame (@pxref{Selection, ,Selecting a Frame}). When
+the innermost frame is selected, this is a good way to delete a
+breakpoint where your program just stopped.
@item clear @var{function}
@itemx clear @var{filename}:@var{function}
@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
+asks confirmation, unless you have @code{set confirm off}). You
can abbreviate this command as @code{d}.
@end table
@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.
+do not 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
+Enabled. The breakpoint will stop your program. A breakpoint set
with the @code{break} command starts out in this state.
@item
-Disabled. The breakpoint has no effect on the program.
+Disabled. The breakpoint has no effect on your program.
@item
-Enabled once. The breakpoint will stop the program, but
+Enabled once. The breakpoint will stop your program, but
when it does so it will become disabled. A breakpoint set
with the @code{tbreak} command starts out in this state.
@item
-Enabled for deletion. The breakpoint will stop the program, but
+Enabled for deletion. The breakpoint will stop your program, but
immediately after it does so it will be deleted permanently.
@end itemize
@kindex enable breakpoints
@kindex enable
Enable the specified breakpoints (or all defined breakpoints). They
-become effective once again in stopping the program.
+become effective once again in stopping your 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.
+again the next time it stops your 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.
+the breakpoints will be deleted the next time it stops your 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{Stepping and Continuing}.)
+Save for a breakpoint set with @code{tbreak} (@pxref{Set Breaks,
+,Setting Breakpoints}), breakpoints that you set are initially
+enabled; subsequently, they become disabled or enabled only when you
+use one of the commands above. (The command @code{until} can set and
+delete a breakpoint of its own, but it will not change the state of
+your other breakpoints; see @ref{Continuing and Stepping, ,Continuing and Stepping}.)
@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
+@c FIXME what is scope of break condition expr? Context where wanted?
+@c in particular for a watchpoint?
+The simplest sort of breakpoint breaks every time your program reaches a
specified place. You can also specify a @dfn{condition} for a
breakpoint. A condition is just a Boolean expression in your
-programming language. (@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.
+programming language (@pxref{Expressions, ,Expressions}). A breakpoint with
+a condition evaluates the expression each time your program reaches it,
+and your program stops only if the condition is @emph{true}.
+
+This is the converse of using assertions for program validation; in that
+situation, you want to stop when the assertion is violated---that is,
+when the condition is false. In C, if you want to test an assertion expressed
+by the condition @var{assert}, you should set the condition
+@samp{! @var{assert}} on the appropriate breakpoint.
Conditions are also accepted for watchpoints; you may not need them,
since a watchpoint is inspecting the value of an expression anyhow---but
it might be simpler, say, to just set a watchpoint on a variable name,
and specify a condition that tests whether the new value is an interesting
-one.
+one.
-Break conditions ca have side effects, and may even call functions in
+Break conditions can have side effects, and may even call functions in
your program. This can be useful, for example, to activate functions
-that log program progress, or to use your own print functions to format
-special data structures. The effects are completely predictable unless
-there is another enabled breakpoint at the same address. (In that
-case, _GDBN__ might see the other breakpoint first and stop 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}).
+that log program progress, or to use your own print functions to
+format special data structures. The effects are completely predictable
+unless there is another enabled breakpoint at the same address. (In
+that case, _GDBN__ might see the other breakpoint first and stop your
+program without checking the condition of this one.) Note that
+breakpoint commands are usually more convenient and flexible for the
+purpose of performing side effects when a breakpoint is reached
+(@pxref{Break Commands, ,Breakpoint Command Lists}).
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
+@samp{if} in the arguments to the @code{break} command. @xref{Set
+Breaks, ,Setting Breakpoints}. They can also be changed at any time
+with the @code{condition} command. The @code{watch} command does not
+recognize the @code{if} keyword; @code{condition} is the only way to
+impose a further condition on a watchpoint.
+
+@table @code
+@item 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
+your program only if the value of @var{expression} is true (nonzero, in
C). When you use @code{condition}, _GDBN__ checks @var{expression}
immediately for syntactic correctness, and to determine whether symbols
-in it have referents in the context of your breakpoint. _GDBN__ does
+in it have referents in the context of your breakpoint.
+@c FIXME so what does GDB do if there is no referent? Moreover, what
+@c about watchpoints?
+_GDBN__ does
not actually evaluate @var{expression} at the time the @code{condition}
-command is given, however. @xref{Expressions}.
+command is given, however. @xref{Expressions, ,Expressions}.
@item condition @var{bnum}
Remove the condition from breakpoint number @var{bnum}. It becomes
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
+therefore has no effect. But if your program reaches a breakpoint whose
ignore count is positive, then instead of stopping, it just decrements
the ignore count by one and continues. As a result, if the ignore count
value is @var{n}, the breakpoint will not stop the next @var{n} times it
@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
+Continue execution of your program, setting the ignore count of the
+breakpoint where your program stopped to @var{count} minus one.
+Thus, your program will not stop at this breakpoint until the
@var{count}'th time it is reached.
-An argument to this command is meaningful only when the program stopped
+An argument to this command is meaningful only when your program stopped
due to a breakpoint. At other times, the argument to @code{continue} is
ignored.
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{$foo-- <= 0}}_1__ using a debugger convenience
-variable that is decremented each time. @xref{Convenience Vars}.
+You could achieve the effect of the ignore count with a condition such
+as _0__@w{@samp{$foo-- <= 0}}_1__ using a debugger convenience variable that
+is decremented each time. @xref{Convenience Vars, ,Convenience
+Variables}.
@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
+execute when your program stops due to that breakpoint. For example, you
might want to print the values of certain expressions, or enable other
breakpoints.
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.
+To remove all commands from a breakpoint, type @code{commands} and
+follow it immediately with @code{end}; that is, give no commands.
With no @var{bnum} argument, @code{commands} refers to the last
breakpoint or watchpoint set (not to the breakpoint most recently
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
+You can use breakpoint commands to start your program up again. Simply
use the @code{continue} command, or @code{step}, or any other command
that resumes execution. Subsequent commands in the command list are
ignored.
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
+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}.
+The commands @code{echo} and @code{output} that allow you to print
+precisely controlled output are often useful in silent breakpoints.
+@xref{Output, ,Commands for Controlled Output}.
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.
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}
+so that your program does not stop, and start with the @code{silent}
command so that no output is produced. Here is an example:
@example
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.
+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.
@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.
+specifies a condition expression (@pxref{Expressions, ,Expressions}) that will
+change @code{x} as needed, then always have the value zero so your
+program will not stop. No input is lost here, because _GDBN__ evaluates
+break conditions without changing the terminal modes. When you want
+to have nontrivial conditions for performing the side effects, the
+operators @samp{&&}, @samp{||} and @samp{?@dots{}:} may be useful.
@node Breakpoint Menus, Error in Breakpoints, Break Commands, Breakpoints
@subsection Breakpoint Menus
-@cindex C++ overloading
+@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.
+@samp{break @var{function}} is not enough to tell _GDBN__ where you want
+a breakpoint. If you realize this will be a problem, you can use
+something like @samp{break @var{function}(@var{types})} to specify which
+particular version of the function you want. Otherwise, _GDBN__ offers
+you a menu of numbered choices for different possible breakpoints, and
+waits for your selection with the prompt @samp{>}. The first two
+options are always @samp{[0] cancel} and @samp{[1] all}. Typing @kbd{1}
+sets a breakpoint at each definition of @var{function}, and typing
+@kbd{0} aborts the @code{break} command without setting any new
+breakpoints.
For example, the following session excerpt shows an attempt to set a
-breakpoint at the overloaded symbol @code{String::after}.
+breakpoint at the overloaded symbol @code{String::after}.
We choose three particular definitions of that function name:
+@c FIXME! This is likely to change to show arg type lists, at least
@example
(_GDBP__) b String::after
[0] cancel
Breakpoint 3 at 0xafcc: file String.cc, line 846.
Multiple breakpoints were set.
Use the "delete" command to delete unwanted breakpoints.
-(_GDBP__)
+(_GDBP__)
@end example
-
@node Error in Breakpoints, , Breakpoint Menus, Breakpoints
@subsection ``Cannot Insert Breakpoints''
-@c FIXME: "cannot insert breakpoints" error, v unclear.
+@c FIXME: "cannot insert breakpoints" error, v unclear.
@c Q in pending mail to Gilmore. ---pesch@cygnus.com, 26mar91
+@c some light may be shed by looking at instances of
+@c ONE_PROCESS_WRITETEXT. But error message seems possible otherwise
+@c too. pesch, 20sep91
Under some operating systems, breakpoints cannot be used in a program if
any other process is running that program. In this situation,
attempting to run or continue a program with a breakpoint causes _GDBN__
Remove or disable the breakpoints, then continue.
@item
-Suspend _GDBN__, and copy the file containing the program to a new name.
+Suspend _GDBN__, and copy the file containing your program to a new name.
Resume _GDBN__ and use the @code{exec-file} command to specify that _GDBN__
-should run the program under that name. Then start the program again.
+should run your program under that name. Then start your 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
+Relink your program so that the text segment is nonsharable, using the
linker option @samp{-N}. The operating system limitation may not apply
to nonsharable executables.
@end enumerate
-@node Stepping and Continuing, Signals, Breakpoints, Stopping
-@section Stepping and Continuing
+@node Continuing and Stepping, Signals, Breakpoints, Stopping
+@section Continuing and Stepping
@cindex stepping
@cindex continuing
@cindex resuming execution
-@dfn{Stepping} means resuming program execution for a very limited time:
-one line of source code, or one machine instruction. @dfn{Continuing}
-means resuming program execution until the program completes normally.
-In either case, 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}.)
+@dfn{Continuing} means resuming program execution until your program
+completes normally. In contrast, @dfn{stepping} means executing just
+one more ``step'' of your program, where ``step'' may mean either one
+line of source code, or one machine instruction (depending on what
+particular command you use). Either when continuing
+or when stepping, your program may stop even sooner, due to a breakpoint
+or to a signal. (If due to a signal, you may want to use @code{handle},
+or use @samp{signal 0} to resume execution. @xref{Signals, ,Signals}.)
+
+@table @code
+@item continue @r{[}@var{ignore-count}@r{]}
+@kindex continue
+Resume program execution, at the address where your program last stopped;
+any breakpoints set at that address are bypassed. The optional argument
+@var{ignore-count} allows you to specify a further number of times to
+ignore a breakpoint at this location; its effect is like that of
+@code{ignore} (@pxref{Conditions, ,Break Conditions}).
+
+To resume execution at a different place, you can use @code{return}
+(@pxref{Returning, ,Returning from a Function}) to go back to the
+calling function; or @code{jump} (@pxref{Jumping, ,Continuing at a
+Different Address}) to go to an arbitrary location in your program.
+@end table
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.
+(@pxref{Breakpoints, ,Breakpoints Watchpoints and Exceptions}) at the
+beginning of the function or the section of your program where a
+problem is believed to lie, run your program until it stops at that
+breakpoint, and then step through the suspect area, examining the
+variables that are interesting, until you see the problem happen.
@table @code
@item step
@kindex step
@kindex s
-Continue running the program until control reaches a different source
+Continue running your program until control reaches a different source
line, then stop it and return control to _GDBN__. This command is
abbreviated @code{s}.
-You may use the @code{step} command even when control is within a function
-compiled without debugging information. In that case, execution
-will proceed until control reaches a different function, or is about to
-return from this function.
+@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
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}).
+Contrast this with the @code{return} command (@pxref{Returning,
+,Returning from a Function}).
@item until
@kindex until
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
+though it, @code{until} will cause your program to continue execution
until the loop is exited. In contrast, a @code{next} command at the end
of a loop will simply step back to the beginning of the loop, which
would force you to step through the next iteration.
-@code{until} always stops the program if it attempts to exit the current
+@code{until} always stops your program if it attempts to exit the current
stack frame.
@code{until} may produce somewhat counterintuitive results if the order
@example
(_GDBP__) f
#0 main (argc=4, argv=0xf7fffae8) at m4.c:206
-206 expand_input();
+206 expand_input();
(_GDBP__) until
-195 for ( ; argc > 0; NEXTARG) @{
+195 for ( ; argc > 0; NEXTARG) @{
@end example
This happened because, for execution efficiency, the compiler had
@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.
+Continue running your program until either the specified location is
+reached, or the current stack frame returns. @var{location} is any of
+the forms of argument acceptable to @code{break} (@pxref{Set Breaks,
+,Setting Breakpoints}). This form of the command uses breakpoints,
+and hence is quicker than @code{until} without an argument.
@item stepi
@itemx si
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}.
+be displayed automatically at each stop. @xref{Auto Display,
+,Automatic Display}.
An argument is a repeat count, as in @code{step}.
proceed until the function returns.
An argument is a repeat count, as in @code{next}.
-
-@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
-
-@node Signals, , Stepping and Continuing, Stopping
+@node Signals, , Continuing and Stepping, Stopping
@section Signals
@cindex signals
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
+the alarm clock timer goes off (which happens only if your 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
+functioning of your program. Others, such as @code{SIGSEGV}, indicate
+errors; these signals are @dfn{fatal} (kill your program immediately) if the
program has not specified in advance some other way to handle the signal.
-@code{SIGINT} does not indicate an error in the program, but it is normally
+@code{SIGINT} does not indicate an error in your program, but it is normally
fatal so it can carry out the purpose of the interrupt: to kill the program.
-_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.
+_GDBN__ has the ability to detect any occurrence of a signal in your
+program. You can tell _GDBN__ in advance what to do for each kind of
+signal.
@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.
+(so as not to interfere with their role in the functioning of your program)
+but to stop your program immediately whenever an error signal happens.
You can change these settings with the @code{handle} command.
@table @code
@table @code
@item nostop
-_GDBN__ should not stop the program when this signal happens. It may
+_GDBN__ should not stop your 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
+_GDBN__ should stop your program when this signal happens. This implies
the @code{print} keyword as well.
@item print
implies the @code{nostop} keyword as well.
@item pass
-_GDBN__ should allow the program to see this signal; the program will be
+_GDBN__ should allow your program to see this signal; your program will be
able to handle the signal, or may be terminated if the signal is fatal
and not handled.
@item nopass
-_GDBN__ should not allow the program to see this signal.
+_GDBN__ should not allow your 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
+When a signal has been set to stop your program, your program cannot see the
signal until you continue. It will see the signal then, if @code{pass} is
-in effect for the signal in question @i{at that time}. In other words,
+in effect for the signal in question @emph{at that time}. In other words,
after _GDBN__ reports a signal, you can use the @code{handle} command with
@code{pass} or @code{nopass} to control whether that signal will be seen by
-the program when you later continue it.
+your program when you later continue it.
-You can also use the @code{signal} command to prevent the program from
+You can also use the @code{signal} command to prevent your program from
seeing a signal, or cause it to see a signal it normally would not see,
-or to give it any signal at any time. For example, if the program stopped
+or to give it any signal at any time. For example, if your program stopped
due to some sort of memory reference error, you might store correct
values into the erroneous variables and continue, hoping to see more
-execution; but 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}.
+execution; but your program would probably terminate immediately as
+a result of the fatal signal once it saw the signal. To prevent this,
+you can continue with @samp{signal 0}. @xref{Signaling, ,Giving your
+Program a Signal}.
@node Stack, Source, Stopping, Top
@chapter Examining the Stack
@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
+where in your program the call was made from is saved in a block of data
called a @dfn{stack frame}. The frame also contains the arguments of the
call and the local variables of the function that was called. All the
stack frames are allocated in a region of memory called the @dfn{call
@cindex selected frame
One of the stack frames is @dfn{selected} by _GDBN__ and many _GDBN__ commands
refer implicitly to the selected frame. In particular, whenever you ask
-_GDBN__ for the value of a variable in the program, the value is found in the
+_GDBN__ for the value of a variable in your program, the value is found in the
selected frame. There are special _GDBN__ commands to select whichever frame
you are interested in.
-When the program stops, _GDBN__ automatically selects the currently executing
+When your program stops, _GDBN__ automatically selects the currently executing
frame and describes it briefly as the @code{frame} command does
-(@pxref{Frame Info, Info}).
+(@pxref{Frame Info, ,Information About a Frame}).
@menu
-* Frames:: Stack Frames
-* Backtrace:: Backtraces
-* Selection:: Selecting a Frame
-* Frame Info:: Information on a Frame
+* Frames:: Stack Frames
+* Backtrace:: Backtraces
+* Selection:: Selecting a Frame
+* Frame Info:: Information on a Frame
@end menu
@node Frames, Backtrace, Stack, Stack
@node Backtrace, Selection, Frames, Stack
@section Backtraces
-A backtrace is a summary of how the program got where it is. It shows one
+A backtrace is a summary of how your program got where it is. It shows one
line per frame, for many frames, starting with the currently executing
frame (frame zero), followed by its caller (frame one), and on up the
stack.
@smallexample
@group
-#0 m4_traceon (obs=0x24eb0, argc=1, argv=0x2b8c8) at builtin.c:993
+#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
@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
+The display for frame zero does not begin with a program counter
+value, indicating that your program has stopped at the beginning of the
code for line @code{993} of @code{builtin.c}.
@node Selection, Frame Info, Backtrace, Stack
@section Selecting a Frame
-Most commands for examining the stack and other data in the program work on
+Most commands for examining the stack and other data in your program work on
whichever stack frame is selected at the moment. Here are the commands for
selecting a stack frame; all of them finish by printing a brief description
of the stack frame just selected.
Select the frame at address @var{addr}. This is useful mainly if the
chaining of stack frames has been damaged by a bug, making it
impossible for _GDBN__ to assign numbers properly to all frames. In
-addition, this can be useful when the program has multiple stacks and
+addition, this can be useful when your program has multiple stacks and
switches between them.
-_if_(_SPARC__)
+_if__(_SPARC__)
On the SPARC architecture, @code{frame} needs two addresses to
-select an arbitrary frame: a frame pointer and a stack pointer.
+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__)
+_fi__(_SPARC__)
@item up @var{n}
@kindex up
example:
@smallexample
+@group
(_GDBP__) up
-#1 0x22f0 in main (argc=1, argv=0xf7fffbf4, env=0xf7fffbfc) at env.c:10
+#1 0x22f0 in main (argc=1, argv=0xf7fffbf4, env=0xf7fffbfc)
+ at env.c:10
10 read_input_file (argv[i]);
+@end group
@end smallexample
-After such a printout, the @code{list} command with no arguments will print
-ten lines centered on the point of execution in the frame. @xref{List}.
+After such a printout, the @code{list} command with no arguments will
+print ten lines centered on the point of execution in the frame.
+@xref{List, ,Printing Source Lines}.
@table @code
@item up-silently @var{n}
respectively; they differ in that they do their work silently, without
causing display of the new frame. They are intended primarily for use
in _GDBN__ command scripts, where the output might be unnecessary and
-distracting.
-
+distracting.
@end table
@node Frame Info, , Selection, Stack
@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
+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}).
+argument, this command is used to select a stack frame
+(@pxref{Selection, ,Selecting a Frame}).
@item info frame
-@kindex info frame
@itemx info f
+@kindex info frame
@kindex info f
This command prints a verbose description of the selected stack frame,
including the address of the frame, the addresses of the next frame down
-(called by this frame) and the next frame up (caller of this frame),
+(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
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}.
+@xref{Exception Handling, ,Breakpoints and Exceptions}.
@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.
+information recorded in your program tells _GDBN__ what source files were
+used to build it. When your program stops, _GDBN__ spontaneously prints
+the line where it stopped. Likewise, when you select a stack frame
+(@pxref{Selection, ,Selecting a Frame}), _GDBN__ prints the line where
+execution in that frame has stopped. You can print other portions of
+source files by explicit command.
-If you use _GDBN__ through its GNU Emacs interface, you may prefer to
-use Emacs facilities to view source; @pxref{Emacs}.
+If you use _GDBN__ through its GNU Emacs interface, you may prefer to use
+Emacs facilities to view source; @pxref{Emacs, ,Using _GDBN__ under GNU
+Emacs}.
@menu
-* List:: Printing Source Lines
-* Search:: Searching Source Files
-* Source Path:: Specifying Source Directories
-* Machine Code:: Source and Machine Code
+* 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
@table @code
@item list @var{linenum}
-Print ten lines centered around line number @var{linenum} in the
+Print lines centered around line number @var{linenum} in the
current source file.
@item list @var{function}
-Print ten lines centered around the beginning of function
+Print lines centered around the beginning of function
@var{function}.
@item list
-Print ten more lines. If the last lines printed were printed with a
-@code{list} command, this prints ten lines following the last lines
+Print more lines. If the last lines printed were printed with a
+@code{list} command, this prints lines following the last lines
printed; however, if the last line printed was a solitary line printed
-as part of displaying a stack frame (@pxref{Stack}), this prints ten
-lines centered around that line.
+as part of displaying a stack frame (@pxref{Stack, ,Examining the
+Stack}), this prints lines centered around that line.
@item list -
-Print ten lines just before the lines last printed.
+Print lines just before the lines last printed.
+@end table
+
+By default, _GDBN__ prints ten source lines with any of these forms of
+the @code{list} command. You can change this using @code{set listsize}:
+
+@table @code
+@item set listsize @var{count}
+@kindex set listsize
+Make the @code{list} command display @var{count} source lines (unless
+the @code{list} argument explicitly specifies some other number).
+
+@item show listsize
+@kindex show listsize
+Display the number of lines that @code{list} will currently display by
+default.
@end table
Repeating a @code{list} command with @key{RET} discards the argument,
@table @code
@item list @var{linespec}
-Print ten lines centered around the line specified by @var{linespec}.
+Print lines centered around the line specified by @var{linespec}.
@item list @var{first},@var{last}
Print lines from @var{first} to @var{last}. Both arguments are
linespecs.
@item list ,@var{last}
-Print ten lines ending with @var{last}.
+Print lines ending with @var{last}.
@item list @var{first},
-Print ten lines starting with @var{first}.
+Print lines starting with @var{first}.
@item list +
-Print ten lines just after the lines last printed.
+Print lines just after the lines last printed.
@item list -
-Print ten lines just before the lines last printed.
+Print lines just before the lines last printed.
@item list
As described in the preceding table.
@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.
+The command @samp{forward-search @var{regexp}} checks each line,
+starting with the one following the last line listed, for a match for
+@var{regexp}. It lists the line that is found. You can use
+synonym @samp{search @var{regexp}} or abbreviate the command name as
+@code{fo}.
@item reverse-search @var{regexp}
The command @samp{reverse-search @var{regexp}} checks each line, starting
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
+If _GDBN__ cannot find a source file in the source path, and the object
program records a directory, _GDBN__ tries that directory too. If the
source path is empty, and there is no record of the compilation
directory, _GDBN__ will, as a last resort, look in the current
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.
+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
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)
+@c repeating it would be a no-op we do not say that. (thanks to RMS)
@item show directories
@kindex show directories
@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.
@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}).
+source line @var{linespec}. You can specify source lines in any of
+the ways understood by the @code{list} command (@pxref{List, ,Printing
+Source Lines}).
@end table
-For example, we can use @code{info line} to inquire on where the object
-code for the first line of function @code{m4_changequote} lies:
+For example, we can use @code{info line} to discover the location of
+the object code for the first line of function
+@code{m4_changequote}:
+
@smallexample
(_GDBP__) info line m4_changecom
Line 895 of "builtin.c" starts at pc 0x634c and ends at 0x6350.
Line 926 of "builtin.c" starts at pc 0x63e4 and ends at 0x6404.
@end smallexample
-@kindex $_
-After @code{info line}, the default address for the @code{x}
-command is changed to the starting address of the line, so that
-@samp{x/i} is sufficient to begin examining the machine code
-(@pxref{Memory}). Also, this address is saved as the value of the
-convenience variable @code{$_} (@pxref{Convenience Vars}).
+@cindex @code{$_} and @code{info line}
+After @code{info line}, the default address for the @code{x} command
+is changed to the starting address of the line, so that @samp{x/i} is
+sufficient to begin examining the machine code (@pxref{Memory,
+,Examining Memory}). Also, this address is saved as the value of the
+convenience variable @code{$_} (@pxref{Convenience Vars, ,Convenience
+Variables}).
@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.
+This specialized command dumps a range of memory as machine
+instructions. The default memory range is the function surrounding the
+program counter of the selected frame. A single argument to this
+command is a program counter value; the function surrounding this value
+will be dumped. Two arguments specify a range of addresses (first
+inclusive, second exclusive) to dump.
@end table
We can use @code{disassemble} to inspect the object code
@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
+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__)
-
@end smallexample
-@node Data, Symbols, Source, Top
+@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 "inspect" is not quite a synonym if you are using Epoch, which we do not
+@c document because it is nonstandard... Under Epoch it displays in a
@c different window or something like that.
The usual way to examine data in your program is with the @code{print}
command (abbreviated @code{p}), or its synonym @code{inspect}. It
-evaluates and prints the value of any valid expression of the language
-the program is written in (for now, C or C++). You type
-
-@example
-print @var{exp}
-@end example
+evaluates and prints the value of an expression of the language your
+program is written in (@pxref{Languages, ,Using _GDBN__ with Different
+Languages}).
-@noindent
-where @var{exp} is any valid expression (in the source language), and
+@table @code
+@item print @var{exp}
+@itemx print /@var{f} @var{exp}
+@var{exp} is an expression (in the source language). By default
the value of @var{exp} is printed in a format appropriate to its data
-type.
+type; you can choose a different format by specifying @samp{/@var{f}},
+where @var{f} is a letter specifying the format; @pxref{Output formats}.
+
+@item print
+@itemx print /@var{f}
+If you omit @var{exp}, _GDBN__ displays the last value again (from the
+@dfn{value history}; @pxref{Value History, ,Value History}). This allows you to
+conveniently inspect the same value in an alternative format.
+@end table
A more low-level way of examining data is with the @code{x} command.
It examines data in memory at a specified address and prints it in a
-specified format. @xref{Memory}.
+specified format. @xref{Memory, ,Examining Memory}.
+
+If you are interested in information about types, or about how the fields
+of a struct or class are declared, use the @code{ptype @var{exp}}
+command rather than @code{print}. @xref{Symbols, ,Examining the Symbol Table}.
@menu
-* Expressions:: Expressions
-* Variables:: Program Variables
-* Arrays:: Artificial Arrays
-* Output formats:: Output formats
-* Memory:: Examining Memory
-* Auto Display:: Automatic Display
-* Print Settings:: Print Settings
-* Value History:: Value History
-* Convenience Vars:: Convenience Variables
-* Registers:: Registers
-* Floating Point Hardware:: Floating Point Hardware
+* 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
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.
-@c FIXME: actually C++ a::b works except in obscure circumstances where it
-@c FIXME...can conflict with GDB's own name scope resolution.
+by preprocessor @code{#define} commands.
+
+Because C is so widespread, most of the expressions shown in examples in
+this manual are in C. @xref{Languages, , Using _GDBN__ with Different
+Languages}, for information on how to use expressions in other
+languages.
+
+In this section, we discuss operators that you can use in _GDBN__
+expressions regardless of your programming language.
Casts are supported in all languages, not just in C, because it is so
useful to cast a number into a pointer so as to examine a structure
at that address in memory.
+@c FIXME: casts supported---Mod2 true?
-_GDBN__ supports three kinds of operator in addition to those of programming
+_GDBN__ supports these operators in addition to those of programming
languages:
@table @code
@item @@
@samp{@@} is a binary operator for treating parts of memory as arrays.
-@xref{Arrays}, for more information.
+@xref{Arrays, ,Artificial Arrays}, for more information.
@item ::
@samp{::} allows you to specify a variable in terms of the file or
-function where it is defined. @xref{Variables}.
+function where it is defined. @xref{Variables, ,Program Variables}.
@item @{@var{type}@} @var{addr}
Refers to an object of type @var{type} stored at address @var{addr} in
memory. @var{addr} may be any expression whose value is an integer or
pointer (but parentheses are required around 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
+normally supposed to reside at @var{addr}.
@end table
@node Variables, Arrays, Expressions, Data
in your program.
Variables in expressions are understood in the selected stack frame
-(@pxref{Selection}); they must either be global (or static) or be visible
-according to the scope rules of the programming language from the point of
-execution in that frame. This means that in the function
+(@pxref{Selection, ,Selecting a Frame}); they must either be global
+(or static) or be visible according to the scope rules of the
+programming language from the point of execution in that frame. This
+means that in the function
@example
foo (a)
@end example
@noindent
-the variable @code{a} is usable whenever the program is executing
+the variable @code{a} is usable whenever your program is executing
within the function @code{foo}, but the variable @code{b} is visible
-only while the program is executing inside the block in which @code{b}
+only while your program is executing inside the block in which @code{b}
is declared.
@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:
+function with the same name (in different source files). If that
+happens, referring to that name has unpredictable effects. If you wish,
+you can specify a static variable in a particular function or file,
+using the colon-colon notation:
@cindex colon-colon
+@iftex
+@c info cannot cope with a :: index entry, but why deprive hard copy readers?
@kindex ::
+@end iftex
@example
@var{file}::@var{variable}
+@var{function}::@var{variable}
@end example
@noindent
-Here @var{file} is the name of the source file whose variable you want.
+Here @var{file} or @var{function} is the name of the context for the
+static @var{variable}.
-@cindex C++ name resolution
+@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++
-name resolution operator in _GDBN__ expressions.
+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 are
+stepping by machine instructions. This is because on most machines, it
+takes more than one instruction to set up a stack frame (including local
+variable definitions); if you are stepping by machine instructions,
+variables may appear to have the wrong values until the stack frame is
+completely built. On function exit, it usually also takes more than one
+machine instruction to destroy a stack frame; after you begin stepping
+through that group of instructions, local variable definitions may be
+gone.
+@end quotation
@node Arrays, Output formats, Variables, Data
@section Artificial Arrays
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.)
+(@pxref{Value History, ,Value History}), after printing one out.)
+
+Sometimes the artificial array mechanism is not quite enough; in
+moderately complex data structures, the elements of interest may not
+actually be adjacent---for example, if you are interested in the values
+of pointers in an array. One useful work-around in this situation is
+to use a convenience variable (@pxref{Convenience Vars, ,Convenience
+Variables}) as a counter in an expression that prints the first
+interesting value, and then repeat that expression via @key{RET}. For
+instance, suppose you have an array @code{dtab} of pointers to
+structures, and you are interested in the values of a field @code{fv}
+in each structure. Here is an example of what you might type:
+
+@example
+set $i = 0
+p dtab[$i++]->fv
+@key{RET}
+@key{RET}
+@dots{}
+@end example
@node Output formats, Memory, Arrays, Data
@section Output formats
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.
@node Memory, Auto Display, Output formats, Data
@section Examining Memory
+You can use the command @code{x} (for ``examine'') to examine memory in
+any of several formats, independently of your program's data types.
+
@cindex examining memory
@table @code
@kindex 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.
+@item x/@var{nfu} @var{addr}
+@itemx x @var{addr}
+@itemx x
+Use the command @code{x} to examine memory.
+@end table
+
+@var{n}, @var{f}, and @var{u} are all optional parameters that specify how
+much memory to display and how to format it; @var{addr} is an
+expression giving the address where you want to start displaying memory.
+If you use defaults for @var{nfu}, you need not type the slash @samp{/}.
+Several commands set convenient defaults for @var{addr}.
+
+@table @r
+@item @var{n}, the repeat count
+The repeat count is a decimal integer; the default is 1. It specifies
+how much memory (counting by units @var{u}) to display.
+@c This really is **decimal**; unaffected by 'set radix' as of GDB
+@c 4.1.2.
+
+@item @var{f}, the display format
+The display format is one of the formats used by @code{print},
+or @samp{s} (null-terminated string) or @samp{i} (machine instruction).
+The default is @samp{x} (hexadecimal) initially, or the format from the
+last time you used either @code{x} or @code{print}.
+
+@item @var{u}, the unit size
+The unit size is any of
+@table @code
+@item b
+Bytes.
+@item h
+Halfwords (two bytes).
+@item w
+Words (four bytes). This is the initial default.
+@item g
+Giant words (eight bytes).
+@end table
+
+Each time you specify a unit size with @code{x}, that size becomes the
+default unit the next time you use @code{x}. (For the @samp{s} and
+@samp{i} formats, the unit size is ignored and is normally not written.)
+
+@item @var{addr}, starting display address
+@var{addr} is the address where you want _GDBN__ to begin displaying
+memory. The expression need not have a pointer value (though it may);
+it is always interpreted as an integer address of a byte of memory.
+@xref{Expressions, ,Expressions}, for more information on expressions. The default for
+@var{addr} is usually just after the last address examined---but several
+other commands also set the default address: @code{info breakpoints} (to
+the address of the last breakpoint listed), @code{info line} (to the
+starting address of a line), and @code{print} (if you use it to display
+a value from memory).
@end table
For example, @samp{x/3uh 0x54320} is a request to display three halfwords
@pxref{Registers}) in hexadecimal (@samp{x}).
Since the letters indicating unit sizes are all distinct from the
-letters specifying output formats, you don't have to remember whether
+letters specifying output formats, you do not have to remember whether
unit size or format comes first; either order will work. The output
specifications @samp{4xw} and @samp{4wx} mean exactly the same thing.
-
-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.
-
-These are the memory units @var{u} you can specify with the @code{x}
-command:
-
-@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.
-
-@item g
-Examine giant words (8 bytes).
-@end table
-
-You can combine these unit specifications with any of the formats
-described for @code{print}. @xref{Output formats}.
-
-@code{x} has two additional output specifications which derive the unit
-size from the data inspected:
-
-@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).
-
-@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
-
-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.
-
-You can also omit the address to examine. Then the address used is just
-after the last unit examined. This is why string and instruction
-formats actually compute a unit-size based on the data: so that the next
-string or instruction examined will start in the right place.
-
-When the @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}).
-
-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.
-
-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,
-
-@example
-x/10i $pc
-@end example
-
-@noindent
-prints ten instructions starting with the one to be executed next in the
-selected frame. After doing this, you could print a further seven
-instructions with
-
-@example
-x/7
-@end example
-
-@noindent
----where the format and address are allowed to default.
-
-@kindex $_
-@kindex $__
-The addresses and contents printed by the @code{x} command are not put
+(However, the count @var{n} must come first; @samp{wx4} will not work.)
+
+Even though the unit size @var{u} is ignored for the formats @samp{s}
+and @samp{i}, you might still want to use a count @var{n}; for example,
+@samp{3i} specifies that you want to see three machine instructions,
+including any operands. The command @code{disassemble} gives an
+alternative way of inspecting machine instructions; @pxref{Machine
+Code}.
+
+All the defaults for the arguments to @code{x} are designed to make it
+easy to continue scanning memory with minimal specifications each time
+you use @code{x}. For example, after you have inspected three machine
+instructions with @samp{x/3i @var{addr}}, you can inspect the next seven
+with just @samp{x/7}. If you use @key{RET} to repeat the @code{x} command,
+the repeat count @var{n} is used again; the other arguments default as
+for successive uses of @code{x}.
+
+@cindex @code{$_}, @code{$__}, and value history
+The addresses and contents printed by the @code{x} command are not saved
in the value history because there is often too much of them and they
would get in the way. Instead, _GDBN__ makes these values available for
subsequent use in expressions as values of the convenience variables
If you find that you want to print the value of an expression frequently
(to see how it changes), you might want to add it to the @dfn{automatic
-display list} so that _GDBN__ will print its value each time the program stops.
+display list} so that _GDBN__ will print its value each time your program stops.
Each expression added to the list is given a number to identify it;
to remove an expression from the list, you specify that number.
The automatic display looks like this:
@item display @var{exp}
@kindex display
Add the expression @var{exp} to the list of expressions to display
-each time the program stops. @xref{Expressions}.
+each time your program stops. @xref{Expressions, ,Expressions}.
@code{display} will not repeat if you press @key{RET} again after using it.
@item display/@var{fmt} @var{addr}
For @var{fmt} @samp{i} or @samp{s}, or including a unit-size or a
number of units, add the expression @var{addr} as a memory address to
-be examined each time the program stops. Examining means in effect
-doing @samp{x/@var{fmt} @var{addr}}. @xref{Memory}.
+be examined each time your program stops. Examining means in effect
+doing @samp{x/@var{fmt} @var{addr}}. @xref{Memory, ,Examining Memory}.
@end table
For example, @samp{display/i $pc} can be helpful, to see the machine
@item display
Display the current values of the expressions on the list, just as is
-done when the program stops.
+done when your program stops.
@item info display
@kindex info display
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
+@code{last_char}, then this argument will be displayed while your program
continues to stop inside that function. When it stops elsewhere---where
there is no variable @code{last_char}---display is disabled. The next time
your program stops where @code{last_char} is meaningful, you can enable the
@cindex format options
@cindex print settings
_GDBN__ provides the following ways to control how arrays, structures,
-and symbols are printed.
+and symbols are printed.
@noindent
These settings are useful for debugging programs in any language:
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
+@group
(_GDBP__) f
-#0 set_quotes (lq=0x34c78 "<<", rq=0x34c88 ">>")
+#0 set_quotes (lq=0x34c78 "<<", rq=0x34c88 ">>")
at input.c:530
-530 if (lquote != def_lquote)
+530 if (lquote != def_lquote)
+@end group
@end smallexample
@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
+@group
(_GDBP__) set print addr off
(_GDBP__) f
#0 set_quotes (lq="<<", rq=">>") at input.c:530
-530 if (lquote != def_lquote)
+530 if (lquote != def_lquote)
+@end group
@end example
@item show print address
@item show print array
@kindex show print array
Show whether compressed or pretty format is selected for displaying
-arrays.
+arrays.
@item set print elements @var{number-of-elements}
@kindex set print elements
line, like this:
@example
+@group
$1 = @{
next = 0x0,
flags = @{
@},
meat = 0x54 "Pork"
@}
+@end group
@end example
@item set print pretty off
Cause _GDBN__ to print structures in a compact format, like this:
@smallexample
-$1 = @{next = 0x0, flags = @{sweet = 1, sour = 1@}, meat \
-= 0x54 "Pork"@}
+@group
+$1 = @{next = 0x0, flags = @{sweet = 1, sour = 1@}, \
+meat = 0x54 "Pork"@}
+@end group
@end smallexample
@noindent
Show which format _GDBN__ will use to print structures.
@item set print sevenbit-strings on
-Print using only seven-bit characters; if this option is set,
+@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}.
is the default.
@item show print sevenbit-strings
+@kindex show print sevenbit-strings
Show whether or not _GDBN__ will print only seven-bit characters.
@item set print union on
@item show print union
@kindex show print union
Ask _GDBN__ whether or not it will print unions which are contained in
-structures.
+structures.
For example, given the declarations
@smallexample
typedef enum @{Tree, Bug@} Species;
typedef enum @{Big_tree, Acorn, Seedling@} Tree_forms;
-typedef enum @{Caterpillar, Cocoon, Butterfly@} Bug_forms;
+typedef enum @{Caterpillar, Cocoon, Butterfly@}
+ Bug_forms;
struct thing @{
Species it;
These settings are of interest when debugging C++ programs:
@table @code
-@item set print demangle
-@itemx set print demangle on
+@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.
@kindex show print demangle
Show whether C++ names will be printed in mangled or demangled form.
-@item set print asm-demangle
-@itemx set print asm-demangle on
+@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.
@kindex show print object
Show whether actual, or declared, object types will be displayed.
-@item set print vtbl
-@itemx set print vtbl on
+@item set print vtbl
+@itemx set print vtbl on
@kindex set print vtbl
Pretty print C++ virtual function tables. The default is off.
@item show print vtbl
@kindex show print vtbl
Show whether C++ virtual function tables are pretty printed, or not.
-
@end table
@node Value History, Convenience Vars, Print Settings, Data
@end table
Pressing @key{RET} to repeat @code{show values @var{n}} has exactly the
-same effect as @samp{show values +}.
+same effect as @samp{show values +}.
@node Convenience Vars, Registers, Value History, Data
@section Convenience Variables
_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.
+of your program. That is why you can use them freely.
Convenience variables are prefixed with @samp{$}. Any name preceded by
@samp{$} can be used for a convenience variable, unless it is one of
the predefined machine-specific register names (@pxref{Registers}).
(Value history references, in contrast, are @emph{numbers} preceded
-by @samp{$}. @xref{Value History}.)
+by @samp{$}. @xref{Value History, ,Value History}.)
You can save a value in a convenience variable with an assignment
expression, just as you would set a variable in your program. Example:
@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{$_}
-to that address; these commands include @code{info line} and @code{info
-breakpoint}.
+the last address examined (@pxref{Memory, ,Examining Memory}). Other
+commands which provide a default address for @code{x} to examine also
+set @code{$_} to that address; these commands include @code{info line}
+and @code{info breakpoint}. The type of @code{$_} is @code{void *}
+except when set by the @code{x} command, in which case it is a pointer
+to the type of @code{$__}.
@item $__
+@kindex $__
The variable @code{$__} is automatically set by the @code{x} command
-to the value found in the last address examined.
+to the value found in the last address examined. Its type is chosen
+to match the format in which the data was printed.
@end table
@node Registers, Floating Point Hardware, Convenience Vars, Data
@section Registers
@cindex registers
-Machine register contents can be referred to in expressions as variables
+You can refer to machine register contents, in expressions, as variables
with names starting with @samp{$}. The names of registers are different
for each machine; use @code{info registers} to see the names used on
-your machine.
+your machine.
@table @code
@item info registers
@kindex info registers
-Print the names and values of all registers (in the selected stack frame).
+Print the names and values of all registers except floating-point
+registers (in the selected stack frame).
+
+@item info all-registers
+@kindex info all-registers
+@cindex floating point registers
+Print the names and values of all registers, including floating-point
+registers.
@item info registers @var{regname}
Print the relativized value of register @var{regname}. @var{regname}
or without the initial @samp{$}.
@end table
-The register names @code{$pc} and @code{$sp} are used on most machines
-for the program counter register and the stack pointer. For example,
+_GDBN__ has four ``standard'' register names that are available (in
+expressions) on most machines---whenever they do not conflict with an
+architecture's canonical mnemonics for registers. The register names
+@code{$pc} and @code{$sp} are used for the program counter register and
+the stack pointer. @code{$fp} is used for a register that contains a
+pointer to the current stack frame, and @code{$ps} is used for a
+register that contains the processor status. For example,
you could print the program counter in hex with
+
@example
p/x $pc
@end example
@noindent
or print the instruction to be executed next with
+
@example
x/i $pc
@end example
-@noindent
-or add four to the stack pointer with
-@example
-set $sp += 4
-@end example
+@noindent
+or add four to the stack pointer @footnote{This is a way of removing
+one word from the stack, on machines where stacks grow downward in
+memory (most machines, nowadays). This assumes that the innermost
+stack frame is selected; setting @code{$sp} is not allowed when other
+stack frames are selected. To pop entire frames off the stack,
+regardless of machine architecture, use @code{return};
+@pxref{Returning, ,Returning from a Function}.} with
+
+@example
+set $sp += 4
+@end example
+
+Whenever possible, these four standard register names are available on
+your machine even though the machine has different canonical mnemonics,
+so long as there is no conflict. The @code{info registers} command
+shows the canonical names. For example, on the SPARC, @code{info
+registers} displays the processor status register as @code{$psr} but you
+can also refer to it as @code{$ps}.
+
+_GDBN__ always considers the contents of an ordinary register as an
+integer when the register is examined in this way. Some machines have
+special registers which can hold nothing but floating point; these
+registers are considered to have floating point values. There is no way
+to refer to the contents of an ordinary register as floating point value
+(although you can @emph{print} it as a floating point value with
+@samp{print/f $@var{regname}}).
+
+Some registers have distinct ``raw'' and ``virtual'' data formats. This
+means that the data format in which the register contents are saved by
+the operating system is not the same one that your program normally
+sees. For example, the registers of the 68881 floating point
+coprocessor are always saved in ``extended'' (raw) format, but all C
+programs expect to work with ``double'' (virtual) format. In such
+cases, _GDBN__ normally works with the virtual format only (the format that
+makes sense for your program), but the @code{info registers} command
+prints the data in both formats.
+
+Normally, register values are relative to the selected stack frame
+(@pxref{Selection, ,Selecting a Frame}). This means that you get the
+value that the register would contain if all stack frames farther in
+were exited and their saved registers restored. In order to see the
+true contents of hardware registers, you must select the innermost
+frame (with @samp{frame 0}).
+
+However, _GDBN__ must deduce where registers are saved, from the machine
+code generated by your compiler. If some registers are not saved, or if
+_GDBN__ is unable to locate the saved registers, the selected stack
+frame will make no difference.
+
+_if__(_AMD29K__)
+@table @code
+@item set rstack_high_address @var{address}
+@kindex set rstack_high_address
+@cindex AMD 29K register stack
+@cindex register stack, AMD29K
+On AMD 29000 family processors, registers are saved in a separate
+``register stack''. There is no way for _GDBN__ to determine the extent
+of this stack. Normally, _GDBN__ just assumes that the stack is ``large
+enough''. This may result in _GDBN__ referencing memory locations that
+don't exist. If necessary, you can get around this problem by
+specifying the ending address of the register stack with the @code{set
+rstack_high_address} command. The argument should be an address, which
+you will probably want to precede with @samp{0x} to specify in
+hexadecimal.
+
+@item show rstack_high_address
+@kindex show rstack_high_address
+Display the current limit of the register stack, on AMD 29000 family
+processors.
+@end table
+_fi__(_AMD29K__)
+
+@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.
+
+@table @code
+@item info float
+@kindex info float
+If available, provides hardware-dependent information about the floating
+point unit. The exact contents and layout vary depending on the
+floating point chip.
+@end table
+@c FIXME: this is a cop-out. Try to get examples, explanations. Only
+@c FIXME...supported currently on arm's and 386's. Mark properly with
+@c FIXME... m4 macros to isolate general statements from hardware-dep,
+@c FIXME... at that point.
+
+@node Languages, Symbols, Data, Top
+@chapter Using _GDBN__ with Different Languages
+@cindex languages
+
+Although programming languages generally have common aspects, they are
+rarely expressed in the same manner. For instance, in ANSI C,
+dereferencing a pointer @code{p} is accomplished by @code{*p}, but in
+Modula-2, it is accomplished by @code{p^}. Values can also be
+represented (and displayed) differently. Hex numbers in C are written
+like @samp{0x1ae}, while in Modula-2 they appear as @samp{1AEH}.
+
+@cindex working language
+Language-specific information is built into _GDBN__ for some languages,
+allowing you to express operations like the above in your program's
+native language, and allowing _GDBN__ to output values in a manner
+consistent with the syntax of your program's native language. The
+language you use to build expressions, called the @dfn{working
+language}, can be selected manually, or _GDBN__ can set it
+automatically.
+
+@menu
+* Setting:: Switching between source languages
+* Show:: Displaying the language
+* Checks:: Type and Range checks
+* Support:: Supported languages
+@end menu
+
+@node Setting, Show, Languages, Languages
+@section Switching between source languages
+
+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.
+
+@menu
+* Manually:: Setting the working language manually
+* Automatically:: Having _GDBN__ infer the source language
+@end menu
+
+@node Manually, Automatically, Setting, Setting
+@subsection Setting the working language
+
+@kindex set language
+To set the language, issue the command @samp{set language @var{lang}},
+where @var{lang} is the name of a language: @code{c} or @code{modula-2}.
+For a list of the supported languages, type @samp{set language}.
+
+Setting the language manually prevents _GDBN__ from updating the working
+language automatically. This can lead to confusion if you try
+to debug a program when the working language is not the same as the
+source language, when an expression is acceptable to both
+languages---but means different things. For instance, if the current
+source file were written in C, and _GDBN__ was parsing Modula-2, a
+command such as:
+
+@example
+print a = b + c
+@end example
+
+@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
+
+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.
+
+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.
+
+@node Show, Checks, Setting, Languages
+@section Displaying the language
+
+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 show language
+Display the current working language. This is the
+language you can use with commands such as @code{print} to
+build and compute expressions that may involve variables in your program.
+
+@item info frame
+Among the other information listed here (@pxref{Frame Info, ,Information
+about a Frame}) is the source language for this frame. This is the
+language that will become the working language if you ever use an
+identifier that is in this frame.
+
+@item info source
+Among the other information listed here (@pxref{Symbols, ,Examining the
+Symbol Table}) is the source language of this source file.
+@end table
+
+@node Checks, Support, Show, Languages
+@section Type and range Checking
+
+@quotation
+@emph{Warning:} In this release, the _GDBN__ commands for type and range
+checking are included, but they do not yet have any effect. This
+section documents the intended facilities.
+@end quotation
+@c FIXME remove warning when type/range code added
+
+Some languages are designed to guard you against making seemingly common
+errors through a series of compile- and run-time checks. These include
+checking the type of arguments to functions and operators, and making
+sure mathematical overflows are caught at run time. Checks such as
+these help to ensure a program's correctness once it has been compiled
+by eliminating type mismatches, and providing active checks for range
+errors when your program is running.
+
+_GDBN__ can check for conditions like the above if you wish.
+Although _GDBN__ will not check the statements in your program, it
+can check expressions entered directly into _GDBN__ for evaluation via
+the @code{print} command, for example. As with the working language,
+_GDBN__ can also decide whether or not to check automatically based on
+your program's source language. @xref{Support, ,Supported Languages},
+for the default settings of supported languages.
+
+@menu
+* Type Checking:: An overview of type checking
+* Range Checking:: An overview of range checking
+@end menu
+
+@cindex type checking
+@cindex checks, type
+@node Type Checking, Range Checking, Checks, Checks
+@subsection An overview of type checking
+
+Some languages, such as Modula-2, are strongly typed, meaning that the
+arguments to operators and functions have to be of the correct type,
+otherwise an error occurs. These checks prevent type mismatch
+errors from ever causing any run-time problems. For example,
+
+@example
+1 + 2 @result{} 3
+@exdent but
+@error{} 1 + 2.3
+@end example
+
+The second example fails because the @code{CARDINAL} 1 is not
+type-compatible with the @code{REAL} 2.3.
+
+For expressions you use in _GDBN__ commands, you can tell the _GDBN__
+type checker to skip checking; to treat any mismatches as errors and
+abandon the expression; or only issue warnings when type mismatches
+occur, but evaluate the expression anyway. When you choose the last of
+these, _GDBN__ evaluates expressions like the second example above, but
+also issues a warning.
+
+Even though you may turn type checking off, other type-based reasons may
+prevent _GDBN__ from evaluating an expression. For instance, _GDBN__ does not
+know how to add an @code{int} and a @code{struct foo}. These particular
+type errors have nothing to do with the language in use, and usually
+arise from expressions, such as the one described above, which make
+little sense to evaluate anyway.
+
+Each language defines to what degree it is strict about type. For
+instance, both Modula-2 and C require the arguments to arithmetical
+operators to be numbers. In C, enumerated types and pointers can be
+represented as numbers, so that they are valid arguments to mathematical
+operators. @xref{Support, ,Supported Languages}, for further
+details on specific languages.
+
+_GDBN__ provides some additional commands for controlling the type checker:
+
+@kindex set check
+@kindex set check type
+@kindex show check type
+@table @code
+@item set check type auto
+Set type checking on or off based on the current working language.
+@xref{Support, ,Supported Languages}, for the default settings for
+each language.
+
+@item set check type on
+@itemx set check type off
+Set type checking on or off, overriding the default setting for the
+current working language. Issue a warning if the setting does not
+match the language's default. If any type mismatches occur in
+evaluating an expression while typechecking is on, _GDBN__ prints a
+message and aborts evaluation of the expression.
+
+@item set check type warn
+Cause the type checker to issue warnings, but to always attempt to
+evaluate the expression. Evaluating the expression may still
+be impossible for other reasons. For example, _GDBN__ cannot add
+numbers and structures.
+
+@item show type
+Show the current setting of the type checker, and whether or not _GDBN__ is
+setting it automatically.
+@end table
+
+@cindex range checking
+@cindex checks, range
+@node Range Checking, , Type Checking, Checks
+@subsection An overview of Range Checking
+
+In some languages (such as Modula-2), it is an error to exceed the
+bounds of a type; this is enforced with run-time checks. Such range
+checking is meant to ensure program correctness by making sure
+computations do not overflow, or indices on an array element access do
+not exceed the bounds of the array.
+
+For expressions you use in _GDBN__ commands, you can tell _GDBN__ to
+ignore range errors; to always treat them as errors and abandon the
+expression; or to issue warnings when a range error occurs but evaluate
+the expression anyway.
+
+A range error can result from numerical overflow, from exceeding an
+array index bound, or when you type in a constant that is not a member
+of any type. Some languages, however, do not treat overflows as an
+error. In many implementations of C, mathematical overflow causes the
+result to ``wrap around'' to lower values---for example, if @var{m} is
+the largest integer value, and @var{s} is the smallest, then
+
+@example
+@var{m} + 1 @result{} @var{s}
+@end example
+
+This, too, is specific to individual languages, and in some cases
+specific to individual compilers or machines. @xref{Support, ,
+Supported Languages}, for further details on specific languages.
+
+_GDBN__ provides some additional commands for controlling the range checker:
+
+@kindex set check
+@kindex set check range
+@kindex show check range
+@table @code
+@item set check range auto
+Set range checking on or off based on the current working language.
+@xref{Support, ,Supported Languages}, for the default settings for
+each language.
+
+@item set check range on
+@itemx set check range off
+Set range checking on or off, overriding the default setting for the
+current working language. A warning is issued if the setting does not
+match the language's default. If a range error occurs, then a message
+is printed and evaluation of the expression is aborted.
+
+@item set check range warn
+Output messages when the _GDBN__ range checker detects a range error,
+but attempt to evaluate the expression anyway. Evaluating the
+expression may still be impossible for other reasons, such as accessing
+memory that the process does not own (a typical example from many UNIX
+systems).
+
+@item show range
+Show the current setting of the range checker, and whether or not it is
+being set automatically by _GDBN__.
+@end table
+
+@node Support, , Checks, Languages
+@section Supported Languages
+
+_GDBN__ 4 supports C, C++, and Modula-2. The syntax for C and C++ is so
+closely related that _GDBN__ does not distinguish the two. Some _GDBN__
+features may be used in expressions regardless of the language you
+use: the _GDBN__ @code{@@} and @code{::} operators, and the
+@samp{@{type@}addr} construct (@pxref{Expressions, ,Expressions}) can be
+used with the constructs of any of the supported languages.
+
+The following sections detail to what degree each of these
+source languages is supported by _GDBN__. These sections are
+not meant to be language tutorials or references, but serve only as a
+reference guide to what the _GDBN__ expression parser will accept, and
+what input and output formats should look like for different languages.
+There are many good books written on each of these languages; please
+look to these for a language reference or tutorial.
+
+@menu
+* C:: C and C++
+* Modula-2:: Modula-2
+@end menu
+
+@node C, Modula-2, Support, Support
+@subsection C and C++
+@cindex C and C++
+
+@cindex expressions in C or C++
+Since C and C++ are so closely related, _GDBN__ does not distinguish
+between them when interpreting the expressions recognized in _GDBN__
+commands.
+
+@cindex C++
+@kindex g++
+@cindex GNU C++
+The C++ debugging facilities are jointly implemented by the GNU C++
+compiler and _GDBN__. Therefore, to debug your C++ code effectively,
+you must compile your C++ programs with the GNU C++ compiler,
+@code{g++}.
+
+@menu
+* C Operators:: C and C++ Operators
+* C Constants:: C and C++ Constants
+* Cplusplus expressions:: C++ Expressions
+* C Defaults:: Default settings for C and C++
+* C Checks:: C and C++ Type and Range Checks
+* Debugging C:: _GDBN__ and C
+* Debugging C plus plus:: Special features for C++
+@end menu
+
+@cindex C and C++ operators
+@node C Operators, C Constants, C, C
+@subsubsection C and C++ Operators
+
+Operators must be defined on values of specific types. For instance,
+@code{+} is defined on numbers, but not on structures. Operators are
+often defined on groups of types. For the purposes of C and C++, the
+following definitions hold:
+
+@itemize @bullet
+@item
+@emph{Integral types} include @code{int} with any of its storage-class
+specifiers, @code{char}, and @code{enum}s.
+
+@item
+@emph{Floating-point types} include @code{float} and @code{double}.
+
+@item
+@emph{Pointer types} include all types defined as @code{(@var{type}
+*)}.
+
+@item
+@emph{Scalar types} include all of the above.
+@end itemize
+
+@noindent
+The following operators are supported. They are listed here
+in order of increasing precedence:
+
+@table @code
+_0__@item ,
+The comma or sequencing operator. Expressions in a comma-separated list
+are evaluated from left to right, with the result of the entire
+expression being the last expression evaluated.
+
+@item =
+Assignment. The value of an assignment expression is the value
+assigned. Defined on scalar types.
+
+@item @var{op}=
+Used in an expression of the form @w{@code{@var{a} @var{op}= @var{b}}},
+and translated to @w{@code{@var{a} = @var{a op b}}}.
+@w{@code{@var{op}=}} and @code{=} have the same precendence.
+@var{op} is any one of the operators @code{|}, @code{^}, @code{&},
+@code{<<}, @code{>>}, @code{+}, @code{-}, @code{*}, @code{/}, @code{%}.
+
+@item ?:
+The ternary operator. @code{@var{a} ? @var{b} : @var{c}} can be thought
+of as: if @var{a} then @var{b} else @var{c}. @var{a} should be of an
+integral type.
+
+@item ||
+Logical @sc{or}. Defined on integral types.
+
+@item &&
+Logical @sc{and}. Defined on integral types.
+
+@item |
+Bitwise @sc{or}. Defined on integral types.
+
+@item ^
+Bitwise exclusive-@sc{or}. Defined on integral types.
+
+@item &
+Bitwise @sc{and}. Defined on integral types.
+
+@item ==@r{, }!=
+Equality and inequality. Defined on scalar types. The value of these
+expressions is 0 for false and non-zero for true.
+
+@item <@r{, }>@r{, }<=@r{, }>=
+Less than, greater than, less than or equal, greater than or equal.
+Defined on scalar types. The value of these expressions is 0 for false
+and non-zero for true.
+
+@item <<@r{, }>>
+left shift, and right shift. Defined on integral types.
+
+@item @@
+The _GDBN__ ``artificial array'' operator (@pxref{Expressions, ,Expressions}).
+
+@item +@r{, }-
+Addition and subtraction. Defined on integral types, floating-point types and
+pointer types.
+
+@item *@r{, }/@r{, }%
+Multiplication, division, and modulus. Multiplication and division are
+defined on integral and floating-point types. Modulus is defined on
+integral types.
+
+@item ++@r{, }--
+Increment and decrement. When appearing before a variable, the
+operation is performed before the variable is used in an expression;
+when appearing after it, the variable's value is used before the
+operation takes place.
+
+@item *
+Pointer dereferencing. Defined on pointer types. Same precedence as
+@code{++}.
+
+@item &
+Address operator. Defined on variables. Same precedence as @code{++}.
+
+For debugging C++, _GDBN__ implements a use of @samp{&} beyond what's
+allowed in the C++ language itself: you can use @samp{&(&@var{ref})}
+(or, if you prefer, simply @samp{&&@var{ref}} to examine the address
+where a C++ reference variable (declared with @samp{&@var{ref}}) is
+stored.
+
+@item -
+Negative. Defined on integral and floating-point types. Same
+precedence as @code{++}.
+
+@item !
+Logical negation. Defined on integral types. Same precedence as
+@code{++}.
+
+@item ~
+Bitwise complement operator. Defined on integral types. Same precedence as
+@code{++}.
+
+@item .@r{, }->
+Structure member, and pointer-to-structure member. For convenience,
+_GDBN__ regards the two as equivalent, choosing whether to dereference a
+pointer based on the stored type information.
+Defined on @code{struct}s and @code{union}s.
+
+@item []
+Array indexing. @code{@var{a}[@var{i}]} is defined as
+@code{*(@var{a}+@var{i})}. Same precedence as @code{->}.
+
+@item ()
+Function parameter list. Same precedence as @code{->}.
+
+@item ::
+C++ scope resolution operator. Defined on
+@code{struct}, @code{union}, and @code{class} types.
+
+@item ::
+The _GDBN__ scope operator (@pxref{Expressions, ,Expressions}). Same precedence as
+@code{::}, above._1__
+@end table
+
+@cindex C and C++ constants
+@node C Constants, Cplusplus expressions, C Operators, C
+@subsubsection C and C++ Constants
+
+_GDBN__ allows you to express the constants of C and C++ in the
+following ways:
+
+@itemize @bullet
+@item
+Integer constants are a sequence of digits. Octal constants are
+specified by a leading @samp{0} (ie. zero), and hexadecimal constants by
+a leading @samp{0x} or @samp{0X}. Constants may also end with a letter
+@samp{l}, specifying that the constant should be treated as a
+@code{long} value.
+
+@item
+Floating point constants are a sequence of digits, followed by a decimal
+point, followed by a sequence of digits, and optionally followed by an
+exponent. An exponent is of the form:
+@samp{@w{e@r{[[}+@r{]|}-@r{]}@var{nnn}}}, where @var{nnn} is another
+sequence of digits. The @samp{+} is optional for positive exponents.
+
+@item
+Enumerated constants consist of enumerated identifiers, or their
+integral equivalents.
+
+@item
+Character constants are a single character surrounded by single quotes
+(@code{'}), or a number---the ordinal value of the corresponding character
+(usually its @sc{ASCII} value). Within quotes, the single character may
+be represented by a letter or by @dfn{escape sequences}, which are of
+the form @samp{\@var{nnn}}, where @var{nnn} is the octal representation
+of the character's ordinal value; or of the form @samp{\@var{x}}, where
+@samp{@var{x}} is a predefined special character---for example,
+@samp{\n} for newline.
+
+@item
+String constants are a sequence of character constants surrounded
+by double quotes (@code{"}).
+
+@item
+Pointer constants are an integral value.
+@end itemize
+
+@node Cplusplus expressions, C Defaults, C Constants, C
+@subsubsection C++ Expressions
+
+@cindex expressions in C++
+_GDBN__'s expression handling has the following extensions to
+interpret a significant subset of C++ expressions:
+
+@enumerate
+
+@cindex member functions
+@item
+Member function calls are allowed; you can use expressions like
+
+@example
+count = aml->GetOriginal(x, y)
+@end example
+
+@kindex this
+@cindex namespace in C++
+@item
+While a member function is active (in the selected stack frame), your
+expressions have the same namespace available as the member function;
+that is, _GDBN__ allows implicit references to the class instance
+pointer @code{this} following the same rules as C++.
+
+@cindex call overloaded functions
+@cindex type conversions in C++
+@item
+You can call overloaded functions; _GDBN__ will resolve the function
+call to the right definition, with one restriction---you must use
+arguments of the type required by the function that you want to call.
+_GDBN__ will not perform conversions requiring constructors or
+user-defined type operators.
+
+@cindex reference declarations
+@item
+_GDBN__ understands variables declared as C++ references; you can use them in
+expressions just as you do in C++ source---they are automatically
+dereferenced.
+
+In the parameter list shown when _GDBN__ displays a frame, the values of
+reference variables are not displayed (unlike other variables); this
+avoids clutter, since references are often used for large structures.
+The @emph{address} of a reference variable is always shown, unless
+you have specified @samp{set print address off}.
+
+@item
+_GDBN__ supports the C++ name resolution operator @code{::}---your
+expressions can use it just as expressions in your program do. Since
+one scope may be defined in another, you can use @code{::} repeatedly if
+necessary, for example in an expression like
+@samp{@var{scope1}::@var{scope2}::@var{name}}. _GDBN__ also allows
+resolving name scope by reference to source files, in both C and C++
+debugging (@pxref{Variables, ,Program Variables}).
+@end enumerate
+
+@node C Defaults, C Checks, Cplusplus expressions, C
+@subsubsection C and C++ Defaults
+@cindex C and C++ defaults
+
+If you allow _GDBN__ to set type and range checking automatically, they
+both default to @code{off} whenever the working language changes to
+C/C++. This happens regardless of whether you, or _GDBN__,
+selected the working language.
+
+If you allow _GDBN__ to set the language automatically, it sets the
+working language to C/C++ on entering code compiled from a source file
+whose name ends with @file{.c} or @file{.cc}.
+@xref{Automatically, ,Having _GDBN__ infer the source language}, for
+further details.
+
+@node C Checks, Debugging C, C Defaults, C
+@subsubsection C and C++ Type and Range Checks
+@cindex C and C++ checks
+
+@quotation
+@emph{Warning:} in this release, _GDBN__ does not yet perform type or
+range checking.
+@end quotation
+@c FIXME remove warning when type/range checks added
+
+By default, when _GDBN__ parses C or C++ expressions, type checking
+is not used. However, if you turn type checking on, _GDBN__ will
+consider two variables type equivalent if:
+
+@itemize @bullet
+@item
+The two variables are structured and have the same structure, union, or
+enumerated tag.
+
+@item
+Two two variables have the same type name, or types that have been
+declared equivalent through @code{typedef}.
+
+@ignore
+@c leaving this out because neither J Gilmore nor R Pesch understand it.
+@c FIXME--beers?
+@item
+The two @code{struct}, @code{union}, or @code{enum} variables are
+declared in the same declaration. (Note: this may not be true for all C
+compilers.)
+@end ignore
+@end itemize
+
+Range checking, if turned on, is done on mathematical operations. Array
+indices are not checked, since they are often used to index a pointer
+that is not itself an array.
+
+@node Debugging C, Debugging C plus plus, C Checks, C
+@subsubsection _GDBN__ and C
+
+The @code{set print union} and @code{show print union} commands apply to
+the @code{union} type. When set to @samp{on}, any @code{union} that is
+inside a @code{struct} or @code{class} will also be printed.
+Otherwise, it will appear as @samp{@{...@}}.
+
+The @code{@@} operator aids in the debugging of dynamic arrays, formed
+with pointers and a memory allocation function. (@pxref{Expressions, ,Expressions})
+
+@node Debugging C plus plus, , Debugging C, C
+@subsubsection _GDBN__ Features for C++
+
+@cindex commands for C++
+Some _GDBN__ commands are particularly useful with C++, and some are
+designed specifically for use with C++. Here is a summary:
+
+@table @code
+@cindex break in overloaded functions
+@item @r{breakpoint menus}
+When you want a breakpoint in a function whose name is overloaded,
+_GDBN__'s breakpoint menus help you specify which function definition
+you want. @xref{Breakpoint Menus}.
+
+@cindex overloading in C++
+@item rbreak @var{regex}
+Setting breakpoints using regular expressions is helpful for setting
+breakpoints on overloaded functions that are not members of any special
+classes.
+@xref{Set Breaks, ,Setting Breakpoints}.
+
+@cindex C++ exception handling
+@item catch @var{exceptions}
+@itemx info catch
+Debug C++ exception handling using these commands. @xref{Exception
+Handling, ,Breakpoints and Exceptions}.
+
+@cindex inheritance
+@item ptype @var{typename}
+Print inheritance relationships as well as other information for type
+@var{typename}.
+@xref{Symbols, ,Examining the Symbol Table}.
+
+@cindex C++ symbol display
+@item set print demangle
+@itemx show print demangle
+@itemx set print asm-demangle
+@itemx show print asm-demangle
+Control whether C++ symbols display in their source form, both when
+displaying code as C++ source and when displaying disassemblies.
+@xref{Print Settings, ,Print Settings}.
+
+@item set print object
+@itemx show print object
+Choose whether to print derived (actual) or declared types of objects.
+@xref{Print Settings, ,Print Settings}.
+
+@item set print vtbl
+@itemx show print vtbl
+Control the format for printing virtual function tables.
+@xref{Print Settings, ,Print Settings}.
+
+@item @r{Overloaded symbol names}
+You can specify a particular definition of an overloaded symbol, using
+the same notation that's used to declare such symbols in C++: type
+@code{@var{symbol}(@var{types})} rather than just @var{symbol}. You can
+also use _GDBN__'s command-line word completion facilities to list the
+available choices, or to finish the type list for you.
+@xref{Completion,, Command Completion}, for details on how to do this.
+@end table
+
+@node Modula-2, , C, Support
+@subsection Modula-2
+@cindex Modula-2
+
+The extensions made to _GDBN__ to support Modula-2 support output
+from the GNU Modula-2 compiler (which is currently being developed).
+Other Modula-2 compilers are not currently supported, and attempting to
+debug executables produced by them will most likely result in an error
+as _GDBN__ reads in the executable's symbol table.
+
+@cindex expressions in Modula-2
+@menu
+* M2 Operators:: Built-in operators
+* Built-In Func/Proc:: Built-in Functions and Procedures
+* M2 Constants:: Modula-2 Constants
+* M2 Defaults:: Default settings for Modula-2
+* Deviations:: Deviations from standard Modula-2
+* M2 Checks:: Modula-2 Type and Range Checks
+* M2 Scope:: The scope operators @code{::} and @code{.}
+* GDB/M2:: _GDBN__ and Modula-2
+@end menu
+
+@node M2 Operators, Built-In Func/Proc, Modula-2, Modula-2
+@subsubsection Operators
+@cindex Modula-2 operators
+
+Operators must be defined on values of specific types. For instance,
+@code{+} is defined on numbers, but not on structures. Operators are
+often defined on groups of types. For the purposes of Modula-2, the
+following definitions hold:
+
+@itemize @bullet
+
+@item
+@emph{Integral types} consist of @code{INTEGER}, @code{CARDINAL}, and
+their subranges.
+
+@item
+@emph{Character types} consist of @code{CHAR} and its subranges.
+
+@item
+@emph{Floating-point types} consist of @code{REAL}.
+
+@item
+@emph{Pointer types} consist of anything declared as @code{POINTER TO
+@var{type}}.
+
+@item
+@emph{Scalar types} consist of all of the above.
+
+@item
+@emph{Set types} consist of @code{SET}s and @code{BITSET}s.
+
+@item
+@emph{Boolean types} consist of @code{BOOLEAN}.
+@end itemize
+
+@noindent
+The following operators are supported, and appear in order of
+increasing precedence:
+
+@table @code
+@item ,
+Function argument or array index separator.
+_0__
+@item :=
+Assignment. The value of @var{var} @code{:=} @var{value} is
+@var{value}.
+
+@item <@r{, }>
+Less than, greater than on integral, floating-point, or enumerated
+types.
+
+@item <=@r{, }>=
+Less than, greater than, less than or equal to, greater than or equal to
+on integral, floating-point and enumerated types, or set inclusion on
+set types. Same precedence as @code{<}.
+
+@item =@r{, }<>@r{, }#
+Equality and two ways of expressing inequality, valid on scalar types.
+Same precedence as @code{<}. In _GDBN__ scripts, only @code{<>} is
+available for inequality, since @code{#} conflicts with the script
+comment character.
+
+@item IN
+Set membership. Defined on set types and the types of their members.
+Same precedence as @code{<}.
+
+@item OR
+Boolean disjunction. Defined on boolean types.
+
+@item AND@r{, }&
+Boolean conjuction. Defined on boolean types.
+
+@item @@
+The _GDBN__ ``artificial array'' operator (@pxref{Expressions, ,Expressions}).
+
+@item +@r{, }-
+Addition and subtraction on integral and floating-point types, or union
+and difference on set types.
+
+@item *
+Multiplication on integral and floating-point types, or set intersection
+on set types.
+
+@item /
+Division on floating-point types, or symmetric set difference on set
+types. Same precedence as @code{*}.
+
+@item DIV@r{, }MOD
+Integer division and remainder. Defined on integral types. Same
+precedence as @code{*}.
+
+@item -
+Negative. Defined on @code{INTEGER}s and @code{REAL}s.
+
+@item ^
+Pointer dereferencing. Defined on pointer types.
+
+@item NOT
+Boolean negation. Defined on boolean types. Same precedence as
+@code{^}.
+
+@item .
+@code{RECORD} field selector. Defined on @code{RECORD}s. Same
+precedence as @code{^}.
+
+@item []
+Array indexing. Defined on @code{ARRAY}s. Same precedence as @code{^}.
+
+@item ()
+Procedure argument list. Defined on @code{PROCEDURE}s. Same precedence
+as @code{^}.
+
+@item ::@r{, }.
+_GDBN__ and Modula-2 scope operators.
+@end table
+
+@quotation
+@emph{Warning:} Sets and their operations are not yet supported, so _GDBN__
+will treat the use of the operator @code{IN}, or the use of operators
+@code{+}, @code{-}, @code{*}, @code{/}, @code{=}, , @code{<>}, @code{#},
+@code{<=}, and @code{>=} on sets as an error.
+@end quotation
+_1__
+@cindex Modula-2 built-ins
+@node Built-In Func/Proc, M2 Constants, M2 Operators, Modula-2
+@subsubsection Built-in Functions and Procedures
+
+Modula-2 also makes available several built-in procedures and functions.
+In describing these, the following metavariables are used:
+
+@table @var
+
+@item a
+represents an @code{ARRAY} variable.
+
+@item c
+represents a @code{CHAR} constant or variable.
+
+@item i
+represents a variable or constant of integral type.
+
+@item m
+represents an identifier that belongs to a set. Generally used in the
+same function with the metavariable @var{s}. The type of @var{s} should
+be @code{SET OF @var{mtype}} (where @var{mtype} is the type of @var{m}.
+
+@item n
+represents a variable or constant of integral or floating-point type.
+
+@item r
+represents a variable or constant of floating-point type.
+
+@item t
+represents a type.
+
+@item v
+represents a variable.
+
+@item x
+represents a variable or constant of one of many types. See the
+explanation of the function for details.
+@end table
+
+All Modula-2 built-in procedures also return a result, described below.
+
+@table @code
+@item ABS(@var{n})
+Returns the absolute value of @var{n}.
+
+@item CAP(@var{c})
+If @var{c} is a lower case letter, it returns its upper case
+equivalent, otherwise it returns its argument
+
+@item CHR(@var{i})
+Returns the character whose ordinal value is @var{i}.
+
+@item DEC(@var{v})
+Decrements the value in the variable @var{v}. Returns the new value.
+
+@item DEC(@var{v},@var{i})
+Decrements the value in the variable @var{v} by @var{i}. Returns the
+new value.
+
+@item EXCL(@var{m},@var{s})
+Removes the element @var{m} from the set @var{s}. Returns the new
+set.
+
+@item FLOAT(@var{i})
+Returns the floating point equivalent of the integer @var{i}.
+
+@item HIGH(@var{a})
+Returns the index of the last member of @var{a}.
+
+@item INC(@var{v})
+Increments the value in the variable @var{v}. Returns the new value.
+
+@item INC(@var{v},@var{i})
+Increments the value in the variable @var{v} by @var{i}. Returns the
+new value.
+
+@item INCL(@var{m},@var{s})
+Adds the element @var{m} to the set @var{s} if it is not already
+there. Returns the new set.
+
+@item MAX(@var{t})
+Returns the maximum value of the type @var{t}.
+
+@item MIN(@var{t})
+Returns the minimum value of the type @var{t}.
+
+@item ODD(@var{i})
+Returns boolean TRUE if @var{i} is an odd number.
+
+@item ORD(@var{x})
+Returns the ordinal value of its argument. For example, the ordinal
+value of a character is its ASCII value (on machines supporting the
+ASCII character set). @var{x} must be of an ordered type, which include
+integral, character and enumerated types.
+
+@item SIZE(@var{x})
+Returns the size of its argument. @var{x} can be a variable or a type.
+
+@item TRUNC(@var{r})
+Returns the integral part of @var{r}.
+
+@item VAL(@var{t},@var{i})
+Returns the member of the type @var{t} whose ordinal value is @var{i}.
+@end table
+
+@quotation
+@emph{Warning:} Sets and their operations are not yet supported, so
+_GDBN__ will treat the use of procedures @code{INCL} and @code{EXCL} as
+an error.
+@end quotation
+
+@cindex Modula-2 constants
+@node M2 Constants, M2 Defaults, Built-In Func/Proc, Modula-2
+@subsubsection Constants
+
+_GDBN__ allows you to express the constants of Modula-2 in the following
+ways:
+
+@itemize @bullet
+
+@item
+Integer constants are simply a sequence of digits. When used in an
+expression, a constant is interpreted to be type-compatible with the
+rest of the expression. Hexadecimal integers are specified by a
+trailing @samp{H}, and octal integers by a trailing @samp{B}.
+
+@item
+Floating point constants appear as a sequence of digits, followed by a
+decimal point and another sequence of digits. An optional exponent can
+then be specified, in the form @samp{E@r{[}+@r{|}-@r{]}@var{nnn}}, where
+@samp{@r{[}+@r{|}-@r{]}@var{nnn}} is the desired exponent. All of the
+digits of the floating point constant must be valid decimal (base 10)
+digits.
+
+@item
+Character constants consist of a single character enclosed by a pair of
+like quotes, either single (@code{'}) or double (@code{"}). They may
+also be expressed by their ordinal value (their ASCII value, usually)
+followed by a @samp{C}.
+
+@item
+String constants consist of a sequence of characters enclosed by a
+pair of like quotes, either single (@code{'}) or double (@code{"}).
+Escape sequences in the style of C are also allowed. @xref{C
+Constants, ,C and C++ Constants}, for a brief explanation of escape
+sequences.
+
+@item
+Enumerated constants consist of an enumerated identifier.
+
+@item
+Boolean constants consist of the identifiers @code{TRUE} and
+@code{FALSE}.
+
+@item
+Pointer constants consist of integral values only.
+
+@item
+Set constants are not yet supported.
+@end itemize
+
+@node M2 Defaults, Deviations, M2 Constants, Modula-2
+@subsubsection Modula-2 Defaults
+@cindex Modula-2 defaults
+
+If type and range checking are set automatically by _GDBN__, they
+both default to @code{on} whenever the working language changes to
+Modula-2. This happens regardless of whether you, or _GDBN__,
+selected the working language.
+
+If you allow _GDBN__ to set the language automatically, then entering
+code compiled from a file whose name ends with @file{.mod} will set the
+working language to Modula-2. @xref{Automatically, ,Having _GDBN__ set
+the language automatically}, for further details.
+
+@node Deviations, M2 Checks, M2 Defaults, Modula-2
+@subsubsection Deviations from Standard Modula-2
+@cindex Modula-2, deviations from
+
+A few changes have been made to make Modula-2 programs easier to debug.
+This is done primarily via loosening its type strictness:
+
+@itemize @bullet
+@item
+Unlike in standard Modula-2, pointer constants can be formed by
+integers. This allows you to modify pointer variables during
+debugging. (In standard Modula-2, the actual address contained in a
+pointer variable is hidden from you; it can only be modified
+through direct assignment to another pointer variable or expression that
+returned a pointer.)
+
+@item
+C escape sequences can be used in strings and characters to represent
+non-printable characters. _GDBN__ will print out strings with these
+escape sequences embedded. Single non-printable characters are
+printed using the @samp{CHR(@var{nnn})} format.
+
+@item
+The assignment operator (@code{:=}) returns the value of its right-hand
+argument.
+
+@item
+All built-in procedures both modify @emph{and} return their argument.
+@end itemize
+
+@node M2 Checks, M2 Scope, Deviations, Modula-2
+@subsubsection Modula-2 Type and Range Checks
+@cindex Modula-2 checks
+
+@quotation
+@emph{Warning:} in this release, _GDBN__ does not yet perform type or
+range checking.
+@end quotation
+@c FIXME remove warning when type/range checks added
+
+_GDBN__ considers two Modula-2 variables type equivalent if:
-@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}.)
-
-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}.
+@itemize @bullet
+@item
+They are of types that have been declared equivalent via a @code{TYPE
+@var{t1} = @var{t2}} statement
-_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}}).
+@item
+They have been declared on the same line. (Note: This is true of the
+GNU Modula-2 compiler, but it may not be true of other compilers.)
+@end itemize
-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.
+As long as type checking is enabled, any attempt to combine variables
+whose types are not equivalent is an error.
-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}).
+Range checking is done on all mathematical operations, assignment, array
+index bounds, and all built-in functions and procedures.
-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.
+@node M2 Scope, GDB/M2, M2 Checks, Modula-2
+@subsubsection The scope operators @code{::} and @code{.}
+@cindex scope
+@kindex .
+@cindex colon, doubled as scope operator
+@ifinfo
+@kindex colon-colon
+@c Info cannot handoe :: but TeX can.
+@end ifinfo
+@iftex
+@kindex ::
+@end iftex
-@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.
+There are a few subtle differences between the Modula-2 scope operator
+(@code{.}) and the _GDBN__ scope operator (@code{::}). The two have
+similar syntax:
-@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.
+@example
-@node Symbols, Altering, Data, Top
+@var{module} . @var{id}
+@var{scope} :: @var{id}
+@end example
+
+@noindent
+where @var{scope} is the name of a module or a procedure,
+@var{module} the name of a module, and @var{id} is any declared
+identifier within your program, except another module.
+
+Using the @code{::} operator makes _GDBN__ search the scope
+specified by @var{scope} for the identifier @var{id}. If it is not
+found in the specified scope, then _GDBN__ will search all scopes
+enclosing the one specified by @var{scope}.
+
+Using the @code{.} operator makes _GDBN__ search the current scope for
+the identifier specified by @var{id} that was imported from the
+definition module specified by @var{module}. With this operator, it is
+an error if the identifier @var{id} was not imported from definition
+module @var{module}, or if @var{id} is not an identifier in
+@var{module}.
+
+@node GDB/M2, , M2 Scope, Modula-2
+@subsubsection _GDBN__ and Modula-2
+
+Some _GDBN__ commands have little use when debugging Modula-2 programs.
+Five subcommands of @code{set print} and @code{show print} apply
+specifically to C and C++: @samp{vtbl}, @samp{demangle},
+@samp{asm-demangle}, @samp{object}, and @samp{union}. The first four
+apply to C++, and the last to C's @code{union} type, which has no direct
+analogue in Modula-2.
+
+The @code{@@} operator (@pxref{Expressions, ,Expressions}), while available
+while using any language, is not useful with Modula-2. Its
+intent is to aid the debugging of @dfn{dynamic arrays}, which cannot be
+created in Modula-2 as they can in C or C++. However, because an
+address can be specified by an integral constant, the construct
+@samp{@{@var{type}@}@var{adrexp}} is still useful. (@pxref{Expressions, ,Expressions})
+_0__
+@cindex @code{#} in Modula-2
+In _GDBN__ scripts, the Modula-2 inequality operator @code{#} is
+interpreted as the beginning of a comment. Use @code{<>} instead.
+_1__
+@node Symbols, Altering, Languages, Top
@chapter Examining the Symbol Table
The commands described in this section allow you to inquire about the
symbols (names of variables, functions and types) defined in your
program. This information is inherent in the text of your program and
-does not change as 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}).
+does not change as your program executes. _GDBN__ finds it in your
+program's symbol table, in the file indicated when you started _GDBN__
+(@pxref{File Options, ,Choosing Files}), or by one of the
+file-management commands (@pxref{Files, ,Commands to Specify Files}).
@table @code
@item info address @var{symbol}
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}.
+@xref{Expressions, ,Expressions}.
@item whatis
Print the data type of @code{$}, the last value in the value history.
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
+@samp{enum @var{enum-tag}}.
@item ptype @var{exp}
+@itemx ptype
Print a description of the type of expression @var{exp}. @code{ptype}
-differs from @code{whatis} by printing a detailed description, instead of just
-the name of the type. For example, if your program declares a variable
-as
+differs from @code{whatis} by printing a detailed description, instead
+of just the name of the type. For example, if your program declares a
+variable as
+
@example
struct complex @{double real; double imag;@} v;
@end example
+
@noindent
compare the output of the two commands:
+
@example
+@group
(_GDBP__) whatis v
type = struct complex
(_GDBP__) ptype v
double real;
double imag;
@}
+@end group
@end example
+@noindent
+As with @code{whatis}, using @code{ptype} without an argument refers to
+the type of @code{$}, the last value in the value history.
+
@item info types @var{regexp}
@itemx info types
-@kindex info types
+@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,
@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.
+the function containing the current point of execution---and the language
+it was written in.
@item info sources
@kindex info sources
-Print the names of all source files in the program for which there is
-debugging information, organized into two lists: those for which symbols
-have been read in, and those for which symbols will be read in on
-demand.
-@c FIXME: above passive AND awkward!
+Print the names of all source files in your program for which there is
+debugging information, organized into two lists: files whose symbols
+have already been read, and files whose symbols will be read when needed.
@item info functions
@kindex info functions
variables) whose names contain a match for regular expression
@var{regexp}.
-
@ignore
This was never implemented.
@item info methods
@end ignore
@item printsyms @var{filename}
+@itemx printpsyms @var{filename}
+@itemx printmsyms @var{filename}
+@kindex printsyms
+@cindex symbol dump
@kindex printsyms
-Write a complete dump of the debugger's symbol data into the
-file @var{filename}.
+@cindex partial symbol dump
+Write a dump of debugging symbol data into the file @var{filename}.
+These commands are used to debug the _GDBN__ symbol-reading code. Only
+symbols with debugging data are included. If you use @code{printsyms},
+_GDBN__ includes all the symbols for which it has already collected full
+details: that is, @var{filename} reflects symbols for only those files
+whose symbols _GDBN__ has read. You can use the command @code{info
+sources} to find out which files these are. If you use
+@code{printpsyms} instead, the dump shows information about symbols that
+_GDBN__ only knows partially---that is, symbols defined in files that
+_GDBN__ has skimmed, but not yet read completely. Finally,
+@code{printmsyms} dumps just the minimal symbol information required for
+each object file from which _GDBN__ has read some symbols. The description of
+@code{symbol-file} explains how _GDBN__ reads symbols; both @code{info
+source} and @code{symbol-file} are described in @ref{Files, ,Commands
+to Specify Files}.
@end table
@node Altering, _GDBN__ Files, Symbols, Top
@chapter Altering Execution
-Once you think you have found an error in the program, you might want to
+Once you think you have found an error in your program, you might want to
find out for certain whether correcting the apparent error would lead to
correct results in the rest of the run. You can find the answer by
experiment, using the _GDBN__ features for altering execution of the
program.
For example, you can store new values into variables or memory
-locations, give the program a signal, restart it at a different address,
+locations, give your program a signal, restart it at a different address,
or even return prematurely from a function to its caller.
@menu
-* Assignment:: Assignment to Variables
-* Jumping:: Continuing at a Different Address
-* Signaling:: Giving the Program a Signal
-* Returning:: Returning from a Function
-* Calling:: Calling your Program's Functions
+* Assignment:: Assignment to Variables
+* Jumping:: Continuing at a Different Address
+* Signaling:: Giving your program a Signal
+* Returning:: Returning from a Function
+* Calling:: Calling your Program's Functions
+* Patching:: Patching your Program
@end menu
@node Assignment, Jumping, Altering, Altering
@cindex assignment
@cindex setting variables
To alter the value of a variable, evaluate an assignment expression.
-@xref{Expressions}. For example,
+@xref{Expressions, ,Expressions}. For example,
@example
print x=4
@end example
@noindent
-would store the value 4 into the variable @code{x}, and then print the
-value of the assignment expression (which is 4). All the assignment
-operators of C are supported, including the increment operators
-@samp{++} and @samp{--}, and combining assignments such as @samp{+=} and
-_0__@samp{<<=}_1__.
+stores the value 4 into the variable @code{x}, and then prints the
+value of the assignment expression (which is 4). @xref{Languages,
+,Using _GDBN__ with Different Languages}, for more information on
+operators in supported languages.
-@kindex set
@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
+printed and is not put in the value history (@pxref{Value History, ,Value History}). The
expression is evaluated only for its effects.
If the beginning of the argument string of the @code{set} command
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:
+we might if @code{set width} did not happen to be a _GDBN__ command:
+
@example
(_GDBP__) whatis width
type = double
(_GDBP__) set width=47
Invalid syntax in expression.
@end example
+
@noindent
The invalid expression, of course, is @samp{=47}. What we can do in
-order to actually set our program's variable @code{width} is
+order to actually set our program's variable @code{width} is
+
@example
(_GDBP__) set var width=47
@end example
-_GDBN__ allows more implicit conversions in assignments than C 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?
+_GDBN__ allows more implicit conversions in assignments than C; you can
+freely store an integer value into a pointer variable or vice versa,
+and any structure can be converted to any other structure that is the
+same length or shorter.
+@comment FIXME: how do structs align/pad in these conversions?
@comment /pesch@cygnus.com 18dec1990
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
+(@pxref{Expressions, ,Expressions}). For example, @code{@{int@}0x83040} refers
to memory location @code{0x83040} as an integer (which implies a certain size
and representation in memory), and
@node Jumping, Signaling, Assignment, Altering
@section Continuing at a Different Address
-Ordinarily, when you continue the program, you do so at the place where
+Ordinarily, when you continue your program, you do so at the place where
it stopped, with the @code{continue} command. You can instead continue at
an address of your own choosing, with the following commands:
@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}.
+immediately if there is a breakpoint there. @xref{List, ,Printing
+Source Lines}, for a description of the different forms of
+@var{linespec}.
The @code{jump} command does not change the current stack frame, or
the stack pointer, or the contents of any memory location or any
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.
+well acquainted with the machine-language code of your program.
@item jump *@var{address}
Resume execution at the instruction at address @var{address}.
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
+does not start your program running; it only changes the address where it
@emph{will} run when it is continued. For example,
@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{Stepping and Continuing}.
+address @code{0x485}, rather than at the address where your program stopped.
+@xref{Continuing and Stepping, ,Continuing and Stepping}.
The most common occasion to use the @code{jump} command is to back up,
perhaps with more breakpoints set, over a portion of a program that has
@node Signaling, Returning, Jumping, Altering
@c @group
-@section Giving the Program a Signal
+@section Giving your program a Signal
@table @code
@item signal @var{signalnum}
@kindex signal
-Resume execution where the program stopped, but give it immediately the
+Resume execution where your program stopped, but give it immediately the
signal number @var{signalnum}.
Alternatively, if @var{signalnum} is zero, continue execution without
-giving a signal. This is useful when the program stopped on account of
+giving a signal. This is useful when your program stopped on account of
a signal and would ordinary see the signal when resumed with the
@code{continue} command; @samp{signal 0} causes it to resume without a
signal.
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.
+value.
@end table
When you use @code{return}, _GDBN__ discards the selected stack frame
discarded frame return prematurely. If you wish to specify a value to
be returned, give that value as the argument to @code{return}.
-This pops the selected stack frame (@pxref{Selection}), 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.
+This pops the selected stack frame (@pxref{Selection, ,Selecting a
+Frame}), and any other frames inside of it, leaving its caller as the
+innermost remaining frame. That frame becomes selected. The
+specified value is stored in the registers used for returning values
+of functions.
The @code{return} command does not resume execution; it leaves the
program stopped in the state that would exist if the function had just
-returned. In contrast, the @code{finish} command (@pxref{Stepping and
-Continuing}) resumes execution until the selected stack frame returns
-naturally.
+returned. In contrast, the @code{finish} command (@pxref{Continuing
+and Stepping, ,Continuing and Stepping}) resumes execution until the
+selected stack frame returns naturally.
-@node Calling, , Returning, Altering
+@node Calling, Patching, Returning, Altering
@section Calling your Program's Functions
@cindex calling functions
with @code{void} returned values. The result is printed and saved in
the value history, if it is not void.
+@node Patching, , Calling, Altering
+@section Patching your Program
+@cindex patching binaries
+@cindex writing into executables
+@cindex writing into corefiles
+
+By default, _GDBN__ opens the file containing your program's executable
+code (or the corefile) read-only. This prevents accidental alterations
+to machine code; but it also prevents you from intentionally patching
+your program's binary.
+
+If you'd like to be able to patch the binary, you can specify that
+explicitly with the @code{set write} command. For example, you might
+want to turn on internal debugging flags, or even to make emergency
+repairs.
+
+@table @code
+@item set write on
+@itemx set write off
+@kindex set write
+If you specify @samp{set write on}, _GDBN__ will open executable and
+core files for both reading and writing; if you specify @samp{set write
+off} (the default), _GDBN__ will open them read-only.
+
+If you have already loaded a file, you must load it
+again (using the @code{exec-file} or @code{core-file} command) after
+changing @code{set write}, for your new setting to take effect.
+
+@item show write
+@kindex show write
+Display whether executable files and core files will be opened for
+writing as well as reading.
+@end table
+
@node _GDBN__ Files, Targets, Altering, Top
@chapter _GDBN__'s Files
+_GDBN__ needs to know the file name of the program to be debugged, both in
+order to read its symbol table and in order to start your program. To
+debug a core dump of a previous run, _GDBN__ must be told the file name of
+the core dump.
+
@menu
-* Files:: Commands to Specify Files
-* Symbol Errors:: Errors Reading Symbol Files
+* Files:: Commands to Specify Files
+* Symbol Errors:: Errors Reading Symbol Files
@end menu
@node Files, Symbol Errors, _GDBN__ Files, _GDBN__ Files
@section Commands to Specify Files
@cindex core dump file
@cindex symbol table
-_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}.
+The usual way to specify executable and core dump file names is with
+the command arguments given when you start _GDBN__, (@pxref{Invocation,
+,Getting In and Out of _GDBN__}.
Occasionally it is necessary to change to a different file during a
_GDBN__ session. Or you may run _GDBN__ and forget to specify the files you
Use @var{filename} as the program to be debugged. It is read for its
symbols and for the contents of pure memory. It is also the program
executed when you use the @code{run} command. If you do not specify a
-directory and the file is not found in _GDBN__'s working directory,
-
-_GDBN__ uses the environment variable @code{PATH} as a list of
-directories to search, just as the shell does when looking for a program
-to run. You can change the value of this variable, for both _GDBN__ and
-your program, using the @code{path} command.
-
+directory and the file is not found in _GDBN__'s working directory, _GDBN__
+uses the environment variable @code{PATH} as a list of directories to
+search, just as the shell does when looking for a program to run. You
+can change the value of this variable, for both _GDBN__ and your program,
+using the @code{path} command.
+
+On systems with memory-mapped files, an auxiliary symbol table file
+@file{@var{filename}.syms} may be available for @var{filename}. If it
+is, _GDBN__ will map in the symbol table from
+@file{@var{filename}.syms}, starting up more quickly. See the
+descriptions of the options @samp{-mapped} and @samp{-readnow} (available
+on the command line, and with the commands @code{file}, @code{symbol-file},
+or @code{add-symbol-file}), for more information.
+
+@item file
@code{file} with no argument makes _GDBN__ discard any information it
has on both executable file and the symbol table.
-@item exec-file @var{filename}
+@item exec-file @r{[} @var{filename} @r{]}
@kindex exec-file
Specify that the program to be run (but not the symbol table) is found
in @var{filename}. _GDBN__ will search the environment variable @code{PATH}
-if necessary to locate the program.
+if necessary to locate your program. Omitting @var{filename} means to
+discard information on the executable file.
-@item symbol-file @var{filename}
+@item symbol-file @r{[} @var{filename} @r{]}
@kindex symbol-file
Read symbol table information from file @var{filename}. @code{PATH} is
searched when necessary. Use the @code{file} command to get both symbol
@code{symbol-file} will not repeat if you press @key{RET} again after
executing it once.
+When _GDBN__ is configured for a particular environment, it will
+understand debugging information in whatever format is the standard
+generated for that environment; you may use either a GNU compiler, or
+other compilers that adhere to the local conventions. Best results are
+usually obtained from GNU compilers; for example, using @code{_GCC__}
+you can generate debugging information for optimized code.
+
On some kinds of object files, the @code{symbol-file} command does not
-actually read the symbol table in full right away. Instead, it scans
+normally read the symbol table in full right away. Instead, it scans
the symbol table quickly to find which source files and which symbols
are present. The details are read later, one source file at a time,
-when they are needed.
+as they are needed.
The purpose of this two-stage reading strategy is to make _GDBN__ start up
-faster. For the most part, it is invisible except for occasional pauses
-while the symbol table details for a particular source file are being
-read. (The @code{set verbose} command can turn these pauses into
-messages if desired. @xref{Messages/Warnings}).
+faster. For the most part, it is invisible except for occasional
+pauses while the symbol table details for a particular source file are
+being read. (The @code{set verbose} command can turn these pauses
+into messages if desired. @xref{Messages/Warnings, ,Optional Warnings
+and Messages}.)
When the symbol table is stored in COFF format, @code{symbol-file} does
-read the symbol table data in full right away. We haven't implemented
+read the symbol table data in full right away. We have not implemented
the two-stage strategy for COFF yet.
-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 core-file @var{filename}
-@itemx core @var{filename}
+@item symbol-file @var{filename} @r{[} -readnow @r{]} @r{[} -mapped @r{]}
+@itemx file @var{filename} @r{[} -readnow @r{]} @r{[} -mapped @r{]}
+@kindex readnow
+@cindex reading symbols immediately
+@cindex symbols, reading immediately
+@kindex mapped
+@cindex memory-mapped symbol file
+@cindex saving symbol table
+You can override the _GDBN__ two-stage strategy for reading symbol
+tables by using the @samp{-readnow} option with any of the commands that
+load symbol table information, if you want to be sure _GDBN__ has the
+entire symbol table available.
+
+If memory-mapped files are available on your system through the
+@code{mmap} system call, you can use another option, @samp{-mapped}, to
+cause _GDBN__ to write the symbols for your program into a reusable
+file. Future _GDBN__ debugging sessions will map in symbol information
+from this auxiliary symbol file (if the program hasn't changed), rather
+than spending time reading the symbol table from the executable
+program. Using the @samp{-mapped} option has the same effect as
+starting _GDBN__ with the @samp{-mapped} command-line option.
+
+You can use both options together, to make sure the auxiliary symbol
+file has all the symbol information for your program.
+
+The @code{.syms} file is specific to the host machine on which GDB is run.
+It holds an exact image of GDB's internal symbol table. It cannot be
+shared across multiple host platforms.
+
+The auxiliary symbol file for a program called @var{myprog} is called
+@samp{@var{myprog}.syms}. Once this file exists (so long as it is newer
+than the corresponding executable), _GDBN__ will always attempt to use
+it when you debug @var{myprog}; no special options or commands are
+needed.
+@c FIXME: for now no mention of directories, since this seems to be in
+@c flux. 13mar1992 status is that in theory GDB would look either in
+@c current dir or in same dir as myprog; but issues like competing
+@c GDB's, or clutter in system dirs, mean that in practice right now
+@c only current dir is used. FFish says maybe a special GDB hierarchy
+@c (eg rooted in val of env var GDBSYMS) could exist for mappable symbol
+@c files.
+
+@item core-file @r{[} @var{filename} @r{]}
@kindex core
@kindex core-file
Specify the whereabouts of a core dump file to be used as the ``contents
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
+under _GDBN__. So, if you have been running your program and you wish to
debug a core file instead, you must kill the subprocess in which the
program is running. To do this, use the @code{kill} command
-(@pxref{Kill Process}).
+(@pxref{Kill Process, ,Killing the Child Process}).
@item load @var{filename}
@kindex load
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{}}''
+@dots{}}''
_fi__(_GENERIC__)
-_if__(_VXWORKS__)
+_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__)
@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__.
+_GDBN__.
_fi__(_I960__)
+_if__(_H8__)
+@cindex download to H8/300
+@cindex H8/300 download
+When you select remote debugging to a Hitachi H8/300 board (@pxref{Hitachi
+H8/300 Remote,,_GDBN__ and the Hitachi H8/300}), the
+@code{load} command downloads your program to the H8/300 and also opens
+it as the current executable target for _GDBN__ on your host (like the
+@code{file} command).
+_fi__(_H8__)
+
@code{load} will not repeat if you press @key{RET} again after using it.
@item add-symbol-file @var{filename} @var{address}
+@itemx add-symbol-file @var{filename} @var{address} @r{[} -readnow @r{]} @r{[} -mapped @r{]}
@kindex add-symbol-file
@cindex dynamic linking
The @code{add-symbol-file} command reads additional symbol table information
-from the file @var{filename}. You would use this command when that file
+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.
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.
+use the @code{symbol-file} command.
@code{add-symbol-file} will not repeat if you press @key{RET} after using it.
+You can use the @samp{-mapped} and @samp{-readnow} options just as with
+the @code{symbol-file} command, to change how _GDBN__ manages the symbol
+tabl einformation for @var{filename}.
+
@item info files
@itemx info target
@kindex info files
@kindex info target
-@code{info files} and @code{info target} are synonymous; both print the
-current targets (@pxref{Targets}), 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.
+@code{info files} and @code{info target} are synonymous; both print
+the current targets (@pxref{Targets, ,Specifying a Debugging Target}),
+including the names of the executable and core dump files currently in
+use by _GDBN__, and the files from which symbols were loaded. The command
+@code{help targets} lists all possible targets rather than current
+ones.
@end table
as arguments. _GDBN__ always converts the file name to an absolute path
name and remembers it that way.
-@kindex sharedlibrary
-@kindex share
@cindex shared libraries
-_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, until after you type @code{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:
+_GDBN__ supports SunOS, SVR4, and IBM RS/6000 shared libraries.
+_GDBN__ automatically loads symbol definitions from shared libraries
+when you use the @code{run} command, or when you examine a core file.
+(Before you issue the @code{run} command, _GDBN__ will not understand
+references to a function in a shared library, however---unless you are
+debugging a core file).
+@c FIXME: next _GDBN__ release should permit some refs to undef
+@c FIXME...symbols---eg in a break cmd---assuming they are from a shared lib
@table @code
-@item 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 you have loaded with the
-@code{sharedlibrary} command.
-@end table
+Print the names of the shared libraries which are currently loaded.
-@code{sharedlibrary} does not repeat automatically when you press
-@key{RET} after using it once.
+@item sharedlibrary @var{regex}
+@itemx share @var{regex}
+@kindex sharedlibrary
+@kindex share
+This is an obsolescent command; you can use it to explicitly
+load shared object library symbols for files matching a UNIX regular
+expression, but as with files loaded automatically, it will only load
+shared libraries required by your program for a core file or after
+typing @code{run}. If @var{regex} is omitted all shared libraries
+required by your program are loaded.
+@end table
@node Symbol Errors, , Files, _GDBN__ Files
@section Errors Reading Symbol Files
-While a 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 @code{set
-complaints} command (@xref{Messages/Warnings}).
+
+While reading a symbol file, _GDBN__ will occasionally encounter problems,
+such as symbol types it does not recognize, or known bugs in compiler
+output. By default, _GDBN__ does not notify you of such problems, since
+they are relatively common and primarily of interest to people
+debugging compilers. If you are interested in seeing information
+about ill-constructed symbol tables, you can either ask _GDBN__ to print
+only one message about each such type of problem, no matter how many
+times the problem occurs; or you can ask _GDBN__ to print more messages,
+to see how many times the problems occur, with the @code{set
+complaints} command (@pxref{Messages/Warnings, ,Optional Warnings and
+Messages}).
The messages currently printed, and their meanings, are:
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.
+in its outer scope blocks.
_GDBN__ circumvents the problem by treating the inner block as if it had
the same scope as the outer block. In the error message, @var{symbol}
@item block at @var{address} out of order
-The symbol information for symbol scope blocks should occur in
+The symbol information for symbol scope blocks should occur in
order of increasing addresses. This error indicates that it does not
-do so.
+do so.
_GDBN__ does not circumvent this problem, and will have trouble locating
symbols in the source file whose symbols being read. (You can often
determine what source file is affected by specifying @code{set verbose
-on}. @xref{Messages/Warnings}.)
+on}. @xref{Messages/Warnings, ,Optional Warnings and Messages}.)
@item bad block start address patched
The symbol information for a symbol scope block has a start address
smaller than the address of the preceding source line. This is known
-to occur in the SunOS 4.1.1 (and earlier) C compiler.
+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.
-@c @item{encountered DBX-style class variable debugging information.
-@c You seem to have compiled your program with "g++ -g0" instead of "g++ -g".
-@c Therefore _GDBN__ will not know about your class variables}
-@c
-@c This error indicates that the symbol information produced for a C++
-@c program includes zero-size fields, which indicated static fields in
-@c a previous release of the G++ compiler. This message is probably
-@c obsolete.
-@c
@item bad string table offset in symbol @var{n}
@cindex foo
Symbol number @var{n} contains a pointer into the string table which is
-larger than the size of the string table.
+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
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.
+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 usually allow your program to be debugged, though certain symbols
will not be accessible. If you encounter such a problem and feel like
debugging it, you can debug @code{_GDBP__} with itself, breakpoint on
@code{complain}, then go up to the function @code{read_dbx_symtab} and
examine @code{*bufp} to see the symbol.
@item stub type has NULL name
-_GDBN__ could not find the full definition for a struct or class.
+_GDBN__ could not find the full definition for a struct or class.
-@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}'
+@item const/volatile indicator missing (ok if using g++ v1.x), got@dots{}
The symbol information for a C++ member function is missing some
-information that the compiler should have output for it.
-@end ignore
+information that recent versions of the compiler should have output
+for it.
-@item C++ type mismatch between compiler and debugger
-
-The debugger could not parse a type specification output by the compiler
-for some C++ object.
+@item info mismatch between compiler and debugger
+_GDBN__ could not parse a type specification output by the compiler.
@end table
@node Targets, Controlling _GDBN__, _GDBN__ Files, Top
-@chapter Specifying a Debugging Target
+@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.
-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.
+A @dfn{target} is the execution environment occupied by your program.
+Often, _GDBN__ runs in the same host environment as your program; in
+that case, the debugging target is specified as a side effect when you
+use the @code{file} or @code{core} commands. When you need more
+flexibility---for example, running _GDBN__ on a physically separate
+host, or controlling a standalone system over a serial port or a
+realtime system over a TCP/IP connection---you can use the @code{target}
+command to specify one of the target types configured for _GDBN__
+(@pxref{Target Commands, ,Commands for Managing Targets}).
@menu
-* Active Targets:: Active Targets
-* Target Commands:: Commands for Managing Targets
-* Remote:: Remote Debugging
+* Active Targets:: Active Targets
+* Target Commands:: Commands for Managing Targets
+* Remote:: Remote Debugging
@end menu
@node Active Targets, Target Commands, Targets, Targets
@cindex active targets
@cindex multiple targets
-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.
-
-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.
-
-When you specify a new target in a given stratum, it replaces any target
-previously in that stratum.
+There are three classes of targets: processes, core files, and
+executable files. _GDBN__ can work concurrently on up to three active
+targets, one in each class. This allows you to (for example) start a
+process and inspect its activity without abandoning your work on a core
+file.
-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}.
+If, for example, you execute @samp{gdb a.out}, then the executable file
+@code{a.out} is the only active target. If you designate a core file as
+well---presumably from a prior run that crashed and coredumped---then
+_GDBN__ has two active targets and will use them in tandem, looking
+first in the corefile target, then in the executable file, to satisfy
+requests for memory addresses. (Typically, these two classes of target
+are complementary, since core files contain only a program's
+read-write memory---variables and so on---plus machine status, while
+executable files contain only the program text and initialized data.)
+
+When you type @code{run}, your executable file becomes an active process
+target as well. When a process target is active, all _GDBN__ commands
+requesting memory addresses refer to that target; addresses in an active
+core file or executable file target are obscured while the process
+target is active.
+
+Use the @code{core-file} and @code{exec-file} commands to select a
+new core file or executable target (@pxref{Files, ,Commands to Specify
+Files}). To specify as a target a process that is already running, use
+the @code{attach} command (@pxref{Attach, ,Debugging an
+Already-Running Process}.).
@node Target Commands, Remote, Active Targets, Targets
@section Commands for Managing Targets
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.
+with, process numbers, and baud rates.
The @code{target} command will not repeat if you press @key{RET} again
after executing the command.
@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}).
+(@pxref{Files, ,Commands to Specify Files}).
@item help target @var{name}
Describe a particular target, including any parameters necessary to
select it.
@end table
-Here are some common targets (available, or not, depending on the _GDBN__
+Here are some common targets (available, or not, depending on the GDB
configuration):
@table @code
@item target remote @var{dev}
@kindex target remote
-Remote serial target in _GDBN__-specific protocol. The argument @var{dev}
+Remote serial target in GDB-specific protocol. The argument @var{dev}
specifies what serial device to use for the connection (e.g.
-@file{/dev/ttya}). @xref{Remote}.
+@file{/dev/ttya}). @xref{Remote, ,Remote Debugging}.
_if__(_AMD29K__)
@item target amd-eb @var{dev} @var{speed} @var{PROG}
@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}.
+@xref{EB29K Remote, ,GDB with a Remote EB29K}.
_fi__(_AMD29K__)
+_if__(_H8__)
+@item target hms
+@kindex target hms
+A Hitachi H8/300 board, attached via serial line to your host. Use
+special commands @code{device} and @code{speed} to control the serial
+line and the communications speed used. @xref{Hitachi H8/300
+Remote,,_GDBN__ and the Hitachi H8/300}.
+
+_fi__(_H8__)
_if__(_I960__)
@item target nindy @var{devicename}
@kindex target nindy
An Intel 960 board controlled by a Nindy Monitor. @var{devicename} is
the name of the serial device to use for the connection, e.g.
-@file{/dev/ttya}. @xref{i960-Nindy Remote}.
+@file{/dev/ttya}. @xref{i960-Nindy Remote, ,_GDBN__ with a Remote i960 (Nindy)}.
_fi__(_I960__)
_if__(_VXWORKS__)
@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}.
+@xref{VxWorks Remote, ,_GDBN__ and VxWorks}.
_fi__(_VXWORKS__)
@end table
@section Remote Debugging
@cindex remote debugging
-_if__(_GENERIC__)
-@menu
-_include__(gdbinv-m.m4)<>_dnl__
-@end menu
-_fi__(_GENERIC__)
-
-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
+If you are trying to debug a program running on a machine that cannot run
+GDB in the usual way, it is often useful to use remote debugging. For
example, you might use remote debugging on an operating system kernel, or on
a small system which does not have a general purpose operating system
-powerful enough to run a full-featured debugger.
+powerful enough to run a full-featured debugger.
-Some configurations of _GDBN__ have special serial or TCP/IP interfaces
+Some configurations of GDB 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
+GDB comes with a generic serial protocol (specific to GDB, but
not specific to any particular target system) which you can use if you
write the remote stubs---the code that will run on the remote system to
-communicate with _GDBN__.
+communicate with GDB.
-To use the _GDBN__ remote serial protocol, the program to be debugged on
+To use the GDB remote serial protocol, the program to be debugged on
the remote machine needs to contain a debugging stub which talks to
-_GDBN__ over the serial line. Several working remote stubs are
-distributed with _GDBN__; see the @file{README} file in the _GDBN__
+GDB over the serial line. Several working remote stubs are
+distributed with GDB; see the @file{README} file in the GDB
distribution for more information.
For details of this communication protocol, see the comments in the
-_GDBN__ source file @file{remote.c}.
+GDB source file @file{remote.c}.
-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
+To start remote debugging, first run GDB and specify as an executable file
+the program that is running in the remote machine. This tells GDB how
+to find your program's symbols and the contents of its pure text. Then
establish communication using the @code{target remote} command with a device
name as an argument. For example:
To resume the remote program and stop debugging it, use the @code{detach}
command.
+@kindex set remotedebug
+@kindex show remotedebug
+@cindex packets, reporting on stdout
+@cindex serial connections, debugging
+If you have trouble with the serial connection, you can use the command
+@code{set remotedebug}. This makes _GDBN__ report on all packets sent
+back and forth across the serial line to the remote machine. The
+packet-debugging information is printed on the _GDBN__ standard output
+stream. @code{set remotedebug off} turns it off, and @code{show
+remotedebug} will show you its current state.
+
Other remote targets may be available in your
-configuration of _GDBN__; use @code{help targets} to list them.
+configuration of GDB; use @code{help targets} to list them.
_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.
+_dnl__ Text on starting up GDB in various specific cases; it goes up front
+_dnl__ in manuals configured for any of those particular situations, here
+_dnl__ otherwise.
+@menu
+_include__(gdbinv-m.m4)<>_dnl__
+@end menu
_include__(gdbinv-s.m4)
_fi__(_GENERIC__)
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.
+data, @pxref{Print Settings, ,Print Settings}; other settings are described here.
@menu
-* Prompt:: Prompt
-* Editing:: Command Editing
-* History:: Command History
-* Screen Size:: Screen Size
-* Numbers:: Numbers
-* Messages/Warnings:: Optional Warnings and Messages
+* Prompt:: Prompt
+* Editing:: Command Editing
+* History:: Command History
+* Screen Size:: Screen Size
+* Numbers:: Numbers
+* Messages/Warnings:: Optional Warnings and Messages
@end menu
@node Prompt, Editing, Controlling _GDBN__, Controlling _GDBN__
@section Prompt
@cindex prompt
+
_GDBN__ indicates its readiness to read a command by printing a string
called the @dfn{prompt}. This string is normally @samp{(_GDBP__)}. You
can change the prompt string with the @code{set prompt} command. For
@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
debugging sessions.
You may control the behavior of command line editing in _GDBN__ with the
-command @code{set}.
+command @code{set}.
@table @code
@kindex set editing
@node History, Screen Size, Editing, Controlling _GDBN__
@section Command History
+
@table @code
@cindex history substitution
@cindex history file
@cindex history expansion
History expansion assigns special meaning to the character @kbd{!}.
@iftex
-(@xref{Event Designators}.)
+@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
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.
+or @code{vi} may wish to read it.
@iftex
@xref{Command Line Editing}.
@end iftex
These commands display the state of the _GDBN__ history parameters.
@code{show history} by itself displays all four states.
@c @end group
-
@end table
@table @code
@item show commands +
Print ten commands just after the commands last printed.
-
@end table
@node Screen Size, Numbers, History, Controlling _GDBN__
@section Screen Size
@cindex size of screen
@cindex pauses in output
+
Certain commands to _GDBN__ may produce large amounts of information
output to the screen. To help you read all of it, _GDBN__ pauses and
asks you for input at the end of each page of output. Type @key{RET}
@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}.
@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
+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 radix 1010
set radix 012
set radix 10.
set radix 0xa
@kindex show radix
@item show radix
Display the current default base for numeric input and display.
-
@end table
@node Messages/Warnings, , Numbers, Controlling _GDBN__
@section Optional Warnings and Messages
+
By default, _GDBN__ is silent about its inner workings. If you are running
on a slow machine, you may want to use the @code{set verbose} command.
It will make _GDBN__ tell you when it does a lengthy internal operation, so
-you won't think it has crashed.
+you will not think it has crashed.
-Currently, the messages controlled by @code{set verbose} are those which
-announce that the symbol table for a source file is being read
-(@pxref{Files}, 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
+Currently, the messages controlled by @code{set verbose} are those
+which announce that the symbol table for a source file is being read
+(@pxref{Files, ,Commands to Specify Files}, in the description of the
+command @code{symbol-file}).
+@c The following is the right way to do it, but emacs 18.55 does not support
@c @ref, and neither the emacs lisp manual version of texinfmt or makeinfo
-@c is released.
+@c is released.
@ignore
-see @code{symbol-file} in @ref{Files}).
+see @code{symbol-file} in @ref{Files, ,Commands to Specify Files}).
@end ignore
@table @code
Displays whether @code{set verbose} is on or off.
@end table
-By default, if _GDBN__ encounters bugs in the symbol table of an object file,
-it prints a single message about each type of problem it finds, then
-shuts up (@pxref{Symbol Errors}). 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.
+By default, if _GDBN__ encounters bugs in the symbol table of an object
+file, it is silent; but if you are debugging a compiler, you may find
+this information useful (@pxref{Symbol Errors, ,Errors Reading Symbol Files}).
@table @code
@kindex set complaints
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)
+Start it from the beginning? (y or n)
@end example
-If you're willing to unflinchingly face the consequences of your own
+If you are willing to unflinchingly face the consequences of your own
commands, you can disable this ``feature'':
@table @code
Displays state of confirmation requests.
@end table
+@c FIXME this does not really belong here. But where *does* it belong?
+@cindex reloading symbols
+Some systems allow individual object files that make up your program to
+be replaced without stopping and restarting your program.
+_if__(_VXWORKS__)
+For example, in VxWorks you can simply recompile a defective object file
+and keep on running.
+_fi__(_VXWORKS__)
+If you are running on one of these systems, you can allow _GDBN__ to
+reload the symbols for automatically relinked modules:
+
+@table @code
+@kindex set symbol-reloading
+@item set symbol-reloading on
+Replace symbol definitions for the corresponding source file when an
+object file with a particular name is seen again.
+
+@item set symbol-reloading off
+Do not replace symbol definitions when re-encountering object files of
+the same name. This is the default state; if you are not running on a
+system that permits automatically relinking modules, you should leave
+@code{symbol-reloading} off, since otherwise _GDBN__ may discard symbols
+when linking large programs, that may contain several modules (from
+different directories or libraries) with the same name.
+
+@item show symbol-reloading
+Show the current @code{on} or @code{off} setting.
+@end table
+
@node Sequences, Emacs, Controlling _GDBN__, Top
@chapter Canned Sequences of Commands
-Aside from breakpoint commands (@pxref{Break Commands}), _GDBN__ provides two
-ways to store sequences of commands for execution as a unit:
-user-defined commands and command files.
+Aside from breakpoint commands (@pxref{Break Commands, ,Breakpoint
+Command Lists}), _GDBN__ provides two ways to store sequences of commands
+for execution as a unit: user-defined commands and command files.
@menu
-* Define:: User-Defined Commands
-* Command Files:: Command Files
-* Output:: Commands for Controlled Output
+* Define:: User-Defined Commands
+* Command Files:: Command Files
+* Output:: Commands for Controlled Output
@end menu
@node Define, Command Files, Sequences, Sequences
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
+@item show user
+@itemx show user @var{commandname}
+@kindex show user
Display the _GDBN__ commands used to define @var{commandname} (but not its
documentation). If no @var{commandname} is given, display the
definitions for all user-defined commands.
@cindex init file
@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:
+@dfn{init files}. These are files named @file{_GDBINIT__}. _GDBN__ reads
+the init file (if any) in your home directory and then the init file
+(if any) in the current working directory. (The init files are not
+executed if you use the @samp{-nx} option; @pxref{Mode Options,
+,Choosing Modes}.) You can also request the execution of a command
+file with the @code{source} command:
@table @code
@item source @var{filename}
@table @code
@item echo @var{text}
@kindex echo
-@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
-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 = \@ }.
-@c FIXME: verify hard copy actually issues enspaces for '@ '! Will this
-@c confuse texinfo?
+@c I do not consider backslash-space a standard C escape sequence
+@c because it is not in ANSI.
+Print @var{text}. Nonprinting characters can be included in
+@var{text} using C escape sequences, such as @samp{\n} to print a
+newline. @strong{No newline will be printed unless you specify one.}
+In addition to the standard C escape sequences, a backslash followed
+by a space stands for a space. This is useful for outputting a
+string with spaces at the beginning or the end, since leading and
+trailing spaces are otherwise trimmed from all arguments.
+To print @samp{@w{ }and foo =@w{ }}, use the command
+@samp{echo \@w{ }and foo = \@w{ }}.
A backslash at the end of @var{text} can be used, as in C, to continue
the command onto subsequent lines. For example,
@kindex output
Print the value of @var{expression} and nothing but that value: no
newlines, no @samp{$@var{nn} = }. The value is not entered in the
-value history either. @xref{Expressions} for more information on
-expressions.
+value history either. @xref{Expressions, ,Expressions}, for more information on
+expressions.
@item output/@var{fmt} @var{expression}
Print the value of @var{expression} in format @var{fmt}. You can use
Print the values of the @var{expressions} under the control of
@var{string}. The @var{expressions} are separated by commas and may
be either numbers or pointers. Their values are printed as specified
-by @var{string}, exactly as if the program were to execute
+by @var{string}, exactly as if your program were to execute
@example
printf (@var{string}, @var{expressions}@dots{});
For example, you can print two values in hex like this:
-@example
+@smallexample
printf "foo, bar-foo = 0x%x, 0x%x\n", foo, bar-foo
-@end example
+@end smallexample
The only backslash-escape sequences that you can use in the format
string are the simple ones that consist of backslash followed by a
letter.
@end table
+_if__(_LUCID__)
+@node Emacs, Energize, Sequences, Top
+_fi__(_LUCID__)
+_if__(!_LUCID__)
@node Emacs, _GDBN__ Bugs, Sequences, Top
+_fi__(!_LUCID__)
@chapter Using _GDBN__ under GNU Emacs
@cindex emacs
@itemize @bullet
@item
-All ``terminal'' input and output goes through the Emacs buffer.
+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
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.
+_GDBN__ displays source code through Emacs.
@end itemize
Each time _GDBN__ displays a stack frame, Emacs automatically finds the
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 @code{PATH} variable, so the _GDBN__ input and output
-session will proceed normally; but Emacs doesn't get enough information
+session will proceed normally; but Emacs does not get enough information
back from _GDBN__ to locate the source files in this situation. To
avoid this problem, either start _GDBN__ mode from the directory where
your program resides, or specify a full path name when prompted for the
you need to call _GDBN__ by a different name (for example, if you keep
several configurations around, with different names) you can set the
Emacs variable @code{gdb-command-name}; for example,
+
@example
(setq gdb-command-name "mygdb")
@end example
+
@noindent
(preceded by @kbd{ESC ESC}, or typed in the @code{*scratch*} buffer, or
in your @file{.emacs} file) will make Emacs call the program named
@code{finish} command.
@item M-c
-Continue execution of the program, like the _GDBN__ @code{continue}
-command. @emph{Warning:} In Emacs v19, this command is @kbd{C-c C-p}.
+Continue execution of your program, like the _GDBN__ @code{continue}
+command.
+
+@emph{Warning:} In Emacs v19, this command is @kbd{C-c C-p}.
@item M-u
Go up the number of frames indicated by the numeric argument
(@pxref{Arguments, , Numeric Arguments, emacs, The GNU Emacs Manual}),
-like the _GDBN__ @code{up} command. @emph{Warning:} In Emacs v19, this
-command is @kbd{C-c C-u}.@refill
+like the _GDBN__ @code{up} command.
+
+@emph{Warning:} In Emacs v19, this command is @kbd{C-c C-u}.
@item M-d
Go down the number of frames indicated by the numeric argument, like the
-_GDBN__ @code{down} command. @emph{Warning:} In Emacs v19, this command
-is @kbd{C-c C-d}.
+_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 @code{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
@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 @code{format}; otherwise the number
is passed as an argument to the corresponding list element.
-
@end table
In any source file, the Emacs command @kbd{C-x SPC} (@code{gdb-break})
@c The following dropped because Epoch is nonstandard. Reactivate
@c if/when v19 does something similar. ---pesch@cygnus.com 19dec1990
@ignore
-@kindex emacs epoch environment
+@kindex emacs epoch environment
@kindex epoch
@kindex inspect
each value is printed in its own window.
@end ignore
+_if__(_LUCID__)
+@node Energize, _GDBN__ Bugs, Emacs, Top
+@chapter Using _GDBN__ with Energize
+
+@cindex Energize
+The Energize Programming System is an integrated development environment
+that includes a point-and-click interface to many programming tools.
+When you use _GDBN__ in this environment, you can use the standard
+Energize graphical interface to drive _GDBN__; you can also, if you
+choose, type _GDBN__ commands as usual in a debugging window. Even if
+you use the graphical interface, the debugging window (which uses Emacs,
+and resembles the standard Emacs interface to _GDBN__) displays the
+equivalent commands, so that the history of your debugging session is
+properly reflected.
+
+When Energize starts up a _GDBN__ session, it uses one of the
+command-line options @samp{-energize} or @samp{-cadillac} (``cadillac''
+is the name of the communications protocol used by the Energize system).
+This option makes _GDBN__ run as one of the tools in the Energize Tool
+Set: it sends all output to the Energize kernel, and accept input from
+it as well.
+
+See the user manual for the Energize Programming System for
+information on how to use the Energize graphical interface and the other
+development tools that Energize integrates with _GDBN__.
+
+@node _GDBN__ Bugs, Renamed Commands, Energize, Top
+_fi__(_LUCID__)
+_if__(!_LUCID__)
@node _GDBN__ Bugs, Renamed Commands, Emacs, Top
+_fi__(!_LUCID__)
@chapter Reporting Bugs in _GDBN__
@cindex Bugs in _GDBN__
@cindex Reporting Bugs in _GDBN__
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
A number of companies and individuals offer support for GNU products.
If you obtained _GDBN__ from a support organization, we recommend you
-contact that organization first.
+contact that organization first.
Contact information for many support companies and individuals is
available in the file @file{etc/SERVICE} in the GNU Emacs distribution.
@samp{help-gdb}, or to any newsgroups.} Most users of _GDBN__ do not want to
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 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.
+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 assume that some details don't matter. Thus, you might
+problem and assume that some details do not matter. Thus, you might
assume that the name of the variable you use in an example does not matter.
-Well, probably it doesn't, but one cannot be sure. Perhaps the bug is a
+Well, probably it does not, but one cannot be sure. Perhaps the bug is a
stray memory reference which happens to fetch from the location where that
name is stored in memory; perhaps, if the name were different, the contents
of that location would fool the debugger into doing the right thing despite
easiest thing for you to do, and the most helpful.
Keep in mind that the purpose of a bug report is to enable us to fix
-the bug if it is new to us. It isn't as important what happens if
+the bug if it is new to us. It is not as important as what happens if
the bug is already known. Therefore, always write your bug reports on
the assumption that the bug has not been reported previously.
The version of _GDBN__. _GDBN__ announces it if you start with no
arguments; you can also print it at any time using @code{show version}.
-Without this, we won't know whether there is any point in looking for
+Without this, we will not know whether there is any point in looking for
the bug in the current version of _GDBN__.
@item
-A complete input script, and all necessary source files, that will
-reproduce the bug.
+The type of machine you are using, and the operating system name and
+version number.
@item
What compiler (and its version) was used to compile _GDBN__---e.g.
-``_GCC__-1.37.1''.
+``_GCC__-2.0''.
+
+@item
+What compiler (and its version) was used to compile the program you
+are debugging---e.g. ``_GCC__-2.0''.
@item
The command arguments you gave the compiler to compile your example and
observe the bug. For example, did you use @samp{-O}? To guarantee
-you won't omit something important, list them all.
+you will not omit something important, list them all. A copy of the
+Makefile (or the output from make) is sufficient.
If we were to try to guess the arguments, we would probably guess wrong
and then we might not encounter the bug.
@item
-The type of machine you are using, and the operating system name and
-version number.
+A complete input script, and all necessary source files, that will
+reproduce the bug.
@item
A description of what behavior you observe that you believe is
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 won't match those in your
+The line numbers in our development sources will not match those in your
sources. Your line numbers would convey no useful information to us.
-
@end itemize
Here are some things that are not necessary:
Of course, if you can find a simpler example to report @emph{instead}
of the original one, that is a convenience for us. Errors in the
output will be easier to spot, running under the debugger will take
-less time, etc.
+less time, etc.
-However, simplification is not vital; if you don't want to do this,
+However, simplification is not vital; if you do not want to do this,
report the bug anyway and send us the entire test case you used.
@item
A patch for the bug.
-A patch for the bug does help us if it is a good one. But don't omit
+A patch for the bug does help us if it is a good one. But do not omit
the necessary information, such as the test case, on the assumption that
a patch is all we need. We might see problems with your patch and decide
to fix the problem another way, or we might not understand it at all.
Sometimes with a program as complicated as _GDBN__ it is very hard to
construct an example that will make the program follow a certain path
-through the code. If you don't send us the example, we won't be able
-to construct one, so we won't be able to verify that the bug is fixed.
+through the code. If you do not send us the example, we will not be able
+to construct one, so we will not be able to verify that the bug is fixed.
-And if we can't understand what bug you are trying to fix, or why your
-patch should be an improvement, we won't install it. A test case will
+And if we cannot understand what bug you are trying to fix, or why your
+patch should be an improvement, we will not install it. A test case will
help us to understand.
@item
A guess about what the bug is or what it depends on.
-Such guesses are usually wrong. Even we can't guess right about such
+Such guesses are usually wrong. Even we cannot guess right about such
things without first using the debugger to find the facts.
@end itemize
+@c Note: no need to update nodes for rdl-apps.texi since it appears
+@c *only* in the TeX version of the manual.
+@c Note: eventually, make a cross reference to the readline Info nodes.
@iftex
-@include rdl-apps.texinfo
+@c appendices describing GNU readline. Distributed with readline code.
+@include rluser.texinfo
+@include inc-hist.texi
@end iftex
-@node Renamed Commands, Installing _GDBN__, _GDBN__ Bugs, Top
+@node Renamed Commands, Formatting Documentation, _GDBN__ Bugs, Top
@appendix Renamed Commands
-The following commands were renamed in _GDBN__ 4.0, in order to make the
+The following commands were renamed in GDB 4, in order to make the
command set as a whole more consistent and easier to use and remember:
-@kindex add-syms
-@kindex delete environment
-@kindex info copying
-@kindex info convenience
-@kindex info directories
-@kindex info editing
-@kindex info history
-@kindex info targets
-@kindex info values
-@kindex info version
-@kindex info warranty
-@kindex set addressprint
-@kindex set arrayprint
-@kindex set prettyprint
-@kindex set screen-height
-@kindex set screen-width
-@kindex set unionprint
-@kindex set vtblprint
-@kindex set demangle
-@kindex set asm-demangle
-@kindex set sevenbit-strings
-@kindex set array-max
-@kindex set caution
-@kindex set history write
-@kindex show addressprint
-@kindex show arrayprint
-@kindex show prettyprint
-@kindex show screen-height
-@kindex show screen-width
-@kindex show unionprint
-@kindex show vtblprint
-@kindex show demangle
-@kindex show asm-demangle
-@kindex show sevenbit-strings
-@kindex show array-max
-@kindex show caution
-@kindex show history write
-@kindex unset
-
+@kindex add-syms
+@kindex delete environment
+@kindex info copying
+@kindex info convenience
+@kindex info directories
+@kindex info editing
+@kindex info history
+@kindex info targets
+@kindex info values
+@kindex info version
+@kindex info warranty
+@kindex set addressprint
+@kindex set arrayprint
+@kindex set prettyprint
+@kindex set screen-height
+@kindex set screen-width
+@kindex set unionprint
+@kindex set vtblprint
+@kindex set demangle
+@kindex set asm-demangle
+@kindex set sevenbit-strings
+@kindex set array-max
+@kindex set caution
+@kindex set history write
+@kindex show addressprint
+@kindex show arrayprint
+@kindex show prettyprint
+@kindex show screen-height
+@kindex show screen-width
+@kindex show unionprint
+@kindex show vtblprint
+@kindex show demangle
+@kindex show asm-demangle
+@kindex show sevenbit-strings
+@kindex show array-max
+@kindex show caution
+@kindex show history write
+@kindex unset
+
+@c TEXI2ROFF-KILL
@ifinfo
-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 ]
+@c END TEXI2ROFF-KILL
+@example
+OLD COMMAND NEW COMMAND
+@c TEXI2ROFF-KILL
+--------------- -------------------------------
+@c END TEXI2ROFF-KILL
+add-syms add-symbol-file
+delete environment unset environment
+info convenience show convenience
+info copying show copying
+info directories show directories
+info editing show commands
+info history show values
+info targets help target
+info values show values
+info version show version
+info warranty show warranty
+set/show addressprint set/show print address
+set/show array-max set/show print elements
+set/show arrayprint set/show print array
+set/show asm-demangle set/show print asm-demangle
+set/show caution set/show confirm
+set/show demangle set/show print demangle
+set/show history write set/show history save
+set/show prettyprint set/show print pretty
+set/show screen-height set/show height
+set/show screen-width set/show width
+set/show sevenbit-strings set/show print sevenbit-strings
+set/show unionprint set/show print union
+set/show vtblprint set/show print vtbl
+
+unset [No longer an alias for delete]
+@end example
+@c TEXI2ROFF-KILL
@end ifinfo
@tex
unset &&\rm(No longer an alias for delete)\cr
}
@end tex
+@c END TEXI2ROFF-KILL
-@node Installing _GDBN__, Copying, Renamed Commands, Top
-@appendix Installing _GDBN__
-@cindex configuring _GDBN__
-@cindex installation
+@node Formatting Documentation, Installing GDB, Renamed Commands, Top
+@appendix Formatting the Documentation
+
+@cindex GDB reference card
+@cindex reference card
+The GDB 4 release includes an already-formatted reference card, ready
+for printing on a PostScript or GhostScript printer, in the @file{gdb}
+subdirectory of the main source directory---in
+@file{gdb-_GDB_VN__/gdb/refcard.ps} of the version _GDB_VN__ release. If you have
+a PostScript or GhostScript printer, you can print the reference card
+by just sending @file{refcard.ps} to the printer.
+
+The release also includes the source for the reference card. You
+can format it, using @TeX{}, by typing:
-_GDBN__ is distributed with a script @code{configure} that automates the
-process of preparing _GDBN__ for installation; you can then use
-@code{make} to actually build it.
-
-You can find the @code{configure} script that's specific to _GDBN__ in
-the main _GDBN__ source directory. However, @code{configure} is
-designed to be called recursively, so it is most convenient to run the
-version of @code{configure} for the @emph{parent} of that directory,
-which should include not only @code{_GDBP__} but also other @sc{gnu}
-tools and libraries. Building _GDBN__ requires some of these associated
-directories; at a minimum, you need a source directory that includes the
-directories
@example
-bfd gdb include libiberty readline
+make refcard.dvi
@end example
-@noindent
-to build _GDBN__. It should also include @file{texinfo} if you want to
-format and print copies of this manual.
-The simplest way to configure and build _GDBN__ is the following:
+The GDB reference card is designed to print in landscape mode on US
+``letter'' size paper; that is, on a sheet 11 inches wide by 8.5 inches
+high. You will need to specify this form of printing as an option to
+your @sc{dvi} output program.
+
+@cindex documentation
+
+All the documentation for GDB comes as part of the machine-readable
+distribution. The documentation is written in Texinfo format, which is
+a documentation system that uses a single source file to produce both
+on-line information and a printed manual. You can use one of the Info
+formatting commands to create the on-line version of the documentation
+and @TeX{} (or @code{texi2roff}) to typeset the printed version.
+
+GDB includes an already formatted copy of the on-line Info version of
+this manual in the @file{gdb} subdirectory. The main Info file is
+@file{gdb-@var{version-number}/gdb/gdb.info}, and it refers to
+subordinate files matching @samp{gdb.info*} in the same directory. If
+necessary, you can print out these files, or read them with any editor;
+but they are easier to read using the @code{info} subsystem in GNU Emacs
+or the standalone @code{info} program, available as part of the GNU
+Texinfo distribution.
+
+If you want to format these Info files yourself, you need one of the
+Info formatting programs, such as @code{texinfo-format-buffer} or
+@code{makeinfo}.
+
+If you have @code{makeinfo} installed, and are in the top level GDB
+source directory (@file{gdb-_GDB_VN__}, in the case of version _GDB_VN__), you can
+make the Info file by typing:
+
+@example
+cd gdb
+make gdb.info
+@end example
+
+If you want to typeset and print copies of this manual, you need
+@TeX{}, a printing program such as @code{lpr}, and @file{texinfo.tex},
+the Texinfo definitions file.
+
+@TeX{} is typesetting program; it does not print files directly, but
+produces output files called @sc{dvi} files. To print a typeset
+document, you need a program to print @sc{dvi} files. If your system
+has @TeX{} installed, chances are it has such a program. The precise
+command to use depends on your system; @kbd{lpr -d} is common; another
+is @kbd{dvips}. The @sc{dvi} print command may require a file name
+without any extension or a @samp{.dvi} extension.
+
+@TeX{} also requires a macro definitions file called
+@file{texinfo.tex}. This file tells @TeX{} how to typeset a document
+written in Texinfo format. On its own, @TeX{} cannot read, much less
+typeset a Texinfo file. @file{texinfo.tex} is distributed with GDB
+and is located in the @file{gdb-@var{version-number}/texinfo}
+directory.
+
+If you have @TeX{} and a @sc{dvi} printer program installed, you can
+typeset and print this manual. First switch to the the @file{gdb}
+subdirectory of the main source directory (for example, to
+@file{gdb-_GDB_VN__/gdb}) and then type:
+
+@example
+make gdb.dvi
+@end example
+
+@node Installing GDB, Copying, Formatting Documentation, Top
+@appendix Installing GDB
+@cindex configuring GDB
+@cindex installation
+
+@iftex
+@c irrelevant in info file; it's as current as the code it lives with.
+@quotation
+@emph{Warning:} These installation instructions are current as of
+GDB version _GDB_VN__. If you're installing a more recent release
+of GDB, we may have improved the installation procedures since
+printing this manual; see the @file{README} file included in your
+release for the most recent instructions.
+@end quotation
+@end iftex
+
+GDB comes with a @code{configure} script that automates the process
+of preparing GDB for installation; you can then use @code{make} to
+build the program.
+
+The GDB distribution includes all the source code you need for GDB in
+a single directory, whose name is usually composed by appending the
+version number to @samp{gdb}.
+
+For example, the GDB version _GDB_VN__ distribution is in the @file{gdb-_GDB_VN__}
+directory. That directory contains:
+
+@table @code
+@item gdb-_GDB_VN__/configure @r{(and supporting files)}
+script for configuring GDB and all its supporting libraries.
+
+@item gdb-_GDB_VN__/gdb
+the source specific to GDB itself
+
+@item gdb-_GDB_VN__/bfd
+source for the Binary File Descriptor library
+
+@item gdb-_GDB_VN__/include
+GNU include files
+
+@item gdb-_GDB_VN__/libiberty
+source for the @samp{-liberty} free software library
+
+@item gdb-_GDB_VN__/readline
+source for the GNU command-line interface
+
+@item gdb-_GDB_VN__/glob
+source for the GNU filename pattern-matching subroutine
+
+@item gdb-_GDB_VN__/mmalloc
+source for the GNU memory-mapped malloc package
+@end table
+
+The simplest way to configure and build GDB is to run @code{configure}
+from the @file{gdb-@var{version-number}} source directory, which in
+this example is the @file{gdb-_GDB_VN__} directory.
+
+First switch to the @file{gdb-@var{version-number}} source directory
+if you are not already in it; then run @code{configure}. Pass the
+identifier for the platform on which GDB will run as an
+argument.
+
+For example:
+
@example
-cd @var{gnusrc}
-./configure @var{machine}
+cd gdb-_GDB_VN__
+./configure @var{host}
make
@end example
+
@noindent
-where @var{gnusrc} is the directory containing both _GDBN__ source and
-source for supporting libraries, in subdirectories; and @var{machine} is
-something like @samp{sun4} or @samp{vax}, that identifies the platform
-where _GDBN__ will run.
-
-The best way to build _GDBN__ is to use subdirectories that record the
-configuration options used; this gives you a clean way of building
-_GDBN__ binaries with several different configuration options.
-@code{configure} only requires this when you simultaneously create
-several configurations; but it's a good habit even for a single
-configuration. You can specify the use of subdirectories using the
-@samp{+forcesubdirs} option (abbreviated @samp{+f}). For example,
-assuming the @sc{gnu} source directory that includes _GDBN__ source and
-the supporting libraries is in a directory called @file{gnusrc}:
+where @var{host} is an identifier such as @samp{sun4} or
+@samp{decstation}, that identifies the platform where GDB will run.
+
+Running @samp{configure @var{host}} followed by @code{make} builds the
+@file{bfd}, @file{readline}, @file{mmalloc}, and @file{libiberty}
+libraries, then @code{gdb} itself. The configured source files, and the
+binaries, are left in the corresponding source directories.
+
+@code{configure} is a Bourne-shell (@code{/bin/sh}) script; if your
+system does not recognize this automatically when you run a different
+shell, you may need to run @code{sh} on it explicitly:
+
+@example
+sh configure @var{host}
+@end example
+
+If you run @code{configure} from a directory that contains source
+directories for multiple libraries or programs, such as the
+@file{gdb-_GDB_VN__} source directory for version _GDB_VN__, @code{configure}
+creates configuration files for every directory level underneath (unless
+you tell it not to, with the @samp{--norecursion} option).
+
+You can run the @code{configure} script from any of the
+subordinate directories in the GDB distribution, if you only want to
+configure that subdirectory; but be sure to specify a path to it.
+
+For example, with version _GDB_VN__, type the following to configure only
+the @code{bfd} subdirectory:
+
+@example
+@group
+cd gdb-_GDB_VN__/bfd
+../configure @var{host}
+@end group
+@end example
+
+You can install @code{_GDBP__} anywhere; it has no hardwired paths.
+However, you should make sure that the shell on your path (named by
+the @samp{SHELL} environment variable) is publicly readable. Remember
+that GDB uses the shell to start your program---some systems refuse to
+let GDB debug child processes whose programs are not readable.
+
+@menu
+* Separate Objdir:: Compiling GDB in another directory
+* Config Names:: Specifying names for hosts and targets
+* configure Options:: Summary of options for configure
+@end menu
+
+@node Separate Objdir, Config Names, Installing GDB, Installing GDB
+@section Compiling GDB in Another Directory
+
+If you want to run GDB versions for several host or target machines,
+you'll need a different @code{gdb} compiled for each combination of
+host and target. @code{configure} is designed to make this easy by
+allowing you to generate each configuration in a separate subdirectory,
+rather than in the source directory. If your @code{make} program
+handles the @samp{VPATH} feature (GNU @code{make} does), running
+@code{make} in each of these directories then builds the @code{gdb}
+program specified there.
+
+To build @code{gdb} in a separate directory, run @code{configure}
+with the @samp{--srcdir} option to specify where to find the source.
+(You'll also need to specify a path to find @code{configure}
+itself from your working directory. If the path to @code{configure}
+would be the same as the argument to @samp{--srcdir}, you can leave out
+the @samp{--srcdir} option; it will be assumed.)
+
+For example, with version _GDB_VN__, you can build GDB in a separate
+directory for a Sun 4 like this:
@example
-cd gnusrc
-./configure +f sun4
-cd Host-sun4/Target-sun4
+@group
+cd gdb-_GDB_VN__
+mkdir ../gdb-sun4
+cd ../gdb-sun4
+../gdb-_GDB_VN__/configure sun4
make
+@end group
@end example
-@noindent
-will build _GDBN__ on a Sun 4.
+When @code{configure} builds a configuration using a remote source
+directory, it creates a tree for the binaries with the same structure
+(and using the same names) as the tree under the source directory. In
+the example, you'd find the Sun 4 library @file{libiberty.a} in the
+directory @file{gdb-sun4/libiberty}, and GDB itself in
+@file{gdb-sun4/gdb}.
+
+One popular reason to build several GDB configurations in separate
+directories is to configure GDB for cross-compiling (where GDB
+runs on one machine---the host---while debugging programs that run on
+another machine---the target). You specify a cross-debugging target by
+giving the @samp{--target=@var{target}} option to @code{configure}.
+
+When you run @code{make} to build a program or library, you must run
+it in a configured directory---whatever directory you were in when you
+called @code{configure} (or one of its subdirectories).
+
+The @code{Makefile} generated by @code{configure} for each source
+directory also runs recursively. If you type @code{make} in a source
+directory such as @file{gdb-_GDB_VN__} (or in a separate configured
+directory configured with @samp{--srcdir=@var{path}/gdb-_GDB_VN__}), you
+will build all the required libraries, then build GDB.
+
+When you have multiple hosts or targets configured in separate
+directories, you can run @code{make} on them in parallel (for example,
+if they are NFS-mounted on each of the hosts); they will not interfere
+with each other.
+
+@node Config Names, configure Options, Separate Objdir, Installing GDB
+@section Specifying Names for Hosts and Targets
+
+The specifications used for hosts and targets in the @code{configure}
+script are based on a three-part naming scheme, but some short predefined
+aliases are also supported. The full naming scheme encodes three pieces
+of information in the following pattern:
-Here is a summary of all the @code{configure} options and arguments that
-you might use for building _GDBN__:
+@example
+@var{architecture}-@var{vendor}-@var{os}
+@end example
+
+For example, you can use the alias @code{sun4} as a @var{host} argument
+or in a @code{--target=@var{target}} option, but the equivalent full name
+is @samp{sparc-sun-sunos4}.
+
+The @code{configure} script accompanying GDB does not provide
+any query facility to list all supported host and target names or
+aliases. @code{configure} calls the Bourne shell script
+@code{config.sub} to map abbreviations to full names; you can read the
+script, if you wish, or you can use it to test your guesses on
+abbreviations---for example:
@example
-configure @r{[}+destdir=@var{dir}@r{]} @r{[}+forcesubdirs@r{]} @r{[}+norecur@r{]} @r{[}+rm@r{]}
- @r{[}+target=@var{machine}@dots{}@r{]} @var{host}@dots{}
+% sh config.sub sun4
+sparc-sun-sunos411
+% sh config.sub sun3
+m68k-sun-sunos411
+% sh config.sub decstation
+mips-dec-ultrix42
+% sh config.sub hp300bsd
+m68k-hp-bsd
+% sh config.sub i386v
+i386-unknown-sysv
+% sh config.sub i786v
+Invalid configuration `i786v': machine `i786v' not recognized
@end example
-You may introduce options with the character @samp{-} rather than
-@samp{+} if you prefer; but options introduced with @samp{+} may be truncated.
-@code{configure} accepts other options, for compatibility with
-configuring other @sc{gnu} tools recursively; but these are the only
-options that affect _GDBN__ or its supporting libraries.
+@noindent
+@code{config.sub} is also distributed in the GDB source
+directory (@file{gdb-_GDB_VN__}, for version _GDB_VN__).
-@table @code
-@item +destdir=@var{dir}
-@var{dir} is an installation directory for use by @code{make install}.
+@node configure Options, , Config Names, Installing GDB
+@section @code{configure} Options
+
+Here is a summary of all the @code{configure} options and arguments that
+you might use for building GDB:
-@item +forcesubdirs
-Build binaries in subdirectories of the form
@example
-Host-@var{machine}/Target-@var{machine}
+configure @r{[}--srcdir=@var{path}@r{]}
+ @r{[}--norecursion@r{]} @r{[}--rm@r{]}
+ @r{[}--target=@var{target}@r{]} @var{host}
@end example
+
@noindent
-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{machine}}
-option on the @code{configure} command line.
-
-@item +norecur
-Configure only the directory where @code{configure} is executed; do not
+You may introduce options with a single @samp{-} rather than
+@samp{--} if you prefer; but you may abbreviate option names if you use
+@samp{--}.
+
+@table @code
+@item --srcdir=@var{path}
+@strong{Warning: using this option requires GNU @code{make}, or another
+@code{make} that implements the @code{VPATH} feature.}@*
+Use this option to make configurations in directories separate from the
+GDB source directories. Among other things, you can use this to
+build (or maintain) several configurations simultaneously, in separate
+directories. @code{configure} writes configuration specific files in
+the current directory, but arranges for them to use the source in the
+directory @var{path}. @code{configure} will create directories under
+the working directory in parallel to the source directories below
+@var{path}.
+
+@item --norecursion
+Configure only the directory level where @code{configure} is executed; do not
propagate configuration to subdirectories.
-@item +rm
-Remove the configuration specified by other arguments.
+@item --rm
+Remove the configuration that the other arguments specify.
+
+@c This does not work (yet if ever). FIXME.
+@c @item --parse=@var{lang} @dots{}
+@c Configure the GDB expression parser to parse the listed languages.
+@c @samp{all} configures GDB for all supported languages. To get a
+@c list of all supported languages, omit the argument. Without this
+@c option, GDB is configured to parse all supported languages.
-@item +target=@var{machine} @dots{}
-Configure _GDBN__ for cross-debugging programs running on specified
-@var{machine}s. You may specify as many @samp{+target} options as you
-wish. To see a list of available targets, execute @samp{ls tconfig} in
-the _GDBN__ source directory. Without this option, _GDBN__ is
-configured to debug programs that run on the same machine (@var{host})
-as _GDBN__ itself.
+@item --target=@var{target}
+Configure GDB for cross-debugging programs running on the specified
+@var{target}. Without this option, GDB is configured to debug
+programs that run on the same machine (@var{host}) as GDB itself.
+
+There is no convenient way to generate a list of all available targets.
@item @var{host} @dots{}
-Configure _GDBN__ to run on specified @var{host}s. You may specify as
-many host names as you wish. To see a list of available hosts, execute
-@samp{ls xconfig} in the _GDBN__ source directory.
+Configure GDB to run on the specified @var{host}.
+
+There is no convenient way to generate a list of all available hosts.
@end table
-@node Copying, Index, Installing _GDBN__, Top
+@noindent
+@code{configure} accepts other options, for compatibility with
+configuring other GNU tools recursively; but these are the only
+options that affect GDB or its supporting libraries.
+
+@node Copying, Index, Installing GDB, Top
@unnumbered GNU GENERAL PUBLIC LICENSE
@center Version 2, June 1991
distribute such modifications or work under the terms of Section 1
above, provided that you also meet all of these conditions:
-@alphaenumerate
+@enumerate a
@item
You must cause the modified files to carry prominent notices
stating that you changed the files and the date of any change.
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
+@end enumerate
These requirements apply to the modified work as a whole. If
identifiable sections of that work are not derived from the Program,
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:
-@alphaenumerate
+@enumerate a
@item
Accompany it with the complete corresponding machine-readable
source code, which must be distributed under the terms of Sections
allowed only for noncommercial distribution and only if you
received the program in object code or executable form with such
an offer, in accord with Subsection b above.)
-@end alphaenumerate
+@end enumerate
The source code for a work means the preferred form of the work for
making modifications to it. For an executable work, complete source
the ``copyright'' line and a pointer to where the full notice is found.
@smallexample
-@var{one line to give the program's name and a brief idea of what it does.}
+@var{one line to give the program's name and an idea of what it does.}
Copyright (C) 19@var{yy} @var{name of author}
-This program is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
+This program is free software; you can redistribute it and/or
+modify it under the terms of the GNU General Public License
+as published by the Free Software Foundation; either version 2
+of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
-along with this program; if not, write to the Free Software
-Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+along with this program; if not, write to the
+Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA.
@end smallexample
Also add information on how to contact you by electronic and paper mail.
@smallexample
Gnomovision version 69, Copyright (C) 19@var{yy} @var{name of author}
-Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
-This is free software, and you are welcome to redistribute it
-under certain conditions; type `show c' for details.
+Gnomovision comes with ABSOLUTELY NO WARRANTY; for details
+type `show w'. This is free software, and you are welcome
+to redistribute it under certain conditions; type `show c'
+for details.
@end smallexample
The hypothetical commands @samp{show w} and @samp{show c} should show
necessary. Here is a sample; alter the names:
@example
-Yoyodyne, Inc., hereby disclaims all copyright interest in the program
-`Gnomovision' (which makes passes at compilers) written by James Hacker.
+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
library. If this is what you want to do, use the GNU Library General
Public License instead of this License.
-
@node Index, , Copying, Top
@unnumbered Index
\centerline{\fontname\tenrm,}
\centerline{with headings in {\bf\fontname\tenbf}}
\centerline{and examples in {\tt\fontname\tentt}.}
-\centerline{{\it\fontname\tenit\/} and}
+\centerline{{\it\fontname\tenit\/},}
+\centerline{{\bf\fontname\tenbf}, and}
\centerline{{\sl\fontname\tensl\/}}
\centerline{are used for emphasis.}\vfill}
\page\colophon
-% Blame: pesch@cygnus.com, 28mar91.
+% Blame: pesch@cygnus.com, 1991.
@end tex
@contents