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This is gdb.info, produced by makeinfo version 4.8 from ./gdb.texinfo.
INFO-DIR-SECTION Software development
START-INFO-DIR-ENTRY
* Gdb: (gdb). The GNU debugger.
END-INFO-DIR-ENTRY
Copyright (C) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996,
1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009,
2010 2011, 2012 Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with the
Invariant Sections being "Free Software" and "Free Software Needs Free
Documentation", with the Front-Cover Texts being "A GNU Manual," and
with the Back-Cover Texts as in (a) below.
(a) The FSF's Back-Cover Text is: "You are free to copy and modify
this GNU Manual. Buying copies from GNU Press supports the FSF in
developing GNU and promoting software freedom."
This file documents the GNU debugger GDB.
This is the Tenth Edition, of `Debugging with GDB: the GNU
Source-Level Debugger' for GDB (GDB) Version 7.5.
Copyright (C) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996,
1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009,
2010 2011, 2012 Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with the
Invariant Sections being "Free Software" and "Free Software Needs Free
Documentation", with the Front-Cover Texts being "A GNU Manual," and
with the Back-Cover Texts as in (a) below.
(a) The FSF's Back-Cover Text is: "You are free to copy and modify
this GNU Manual. Buying copies from GNU Press supports the FSF in
developing GNU and promoting software freedom."

File: gdb.info, Node: objfile-gdb.py file, Next: dotdebug_gdb_scripts section, Up: Python Auto-loading
23.2.3.1 The `OBJFILE-gdb.py' file
..................................
When a new object file is read, GDB looks for a file named
`OBJFILE-gdb.py' (we call it SCRIPT-NAME below), where OBJFILE is the
object file's real name, formed by ensuring that the file name is
absolute, following all symlinks, and resolving `.' and `..'
components. If this file exists and is readable, GDB will evaluate it
as a Python script.
If this file does not exist, then GDB will look for SCRIPT-NAME file
in all of the directories as specified below.
Note that loading of this script file also requires accordingly
configured `auto-load safe-path' (*note Auto-loading safe path::).
`set auto-load scripts-directory [DIRECTORIES]'
Control GDB auto-loaded scripts location. Multiple directory
entries may be delimited by the host platform path separator in use
(`:' on Unix, `;' on MS-Windows and MS-DOS).
Each entry here needs to be covered also by the security setting
`set auto-load safe-path' (*note set auto-load safe-path::).
This variable defaults to `$debugdir:$datadir/auto-load'. The
default `set auto-load safe-path' value can be also overriden by
GDB configuration option `--with-auto-load-dir'.
Any reference to `$debugdir' will get replaced by
DEBUG-FILE-DIRECTORY value (*note Separate Debug Files::) and any
reference to `$datadir' will get replaced by DATA-DIRECTORY which
is determined at GDB startup (*note Data Files::). `$debugdir' and
`$datadir' must be placed as a directory component -- either alone
or delimited by `/' or `\' directory separators, depending on the
host platform.
The list of directories uses path separator (`:' on GNU and Unix
systems, `;' on MS-Windows and MS-DOS) to separate directories,
similarly to the `PATH' environment variable.
`show auto-load scripts-directory'
Show GDB auto-loaded scripts location.
GDB does not track which files it has already auto-loaded this way.
GDB will load the associated script every time the corresponding
OBJFILE is opened. So your `-gdb.py' file should be careful to avoid
errors if it is evaluated more than once.

File: gdb.info, Node: dotdebug_gdb_scripts section, Next: Which flavor to choose?, Prev: objfile-gdb.py file, Up: Python Auto-loading
23.2.3.2 The `.debug_gdb_scripts' section
.........................................
For systems using file formats like ELF and COFF, when GDB loads a new
object file it will look for a special section named
`.debug_gdb_scripts'. If this section exists, its contents is a list
of names of scripts to load.
GDB will look for each specified script file first in the current
directory and then along the source search path (*note Specifying
Source Directories: Source Path.), except that `$cdir' is not searched,
since the compilation directory is not relevant to scripts.
Entries can be placed in section `.debug_gdb_scripts' with, for
example, this GCC macro:
/* Note: The "MS" section flags are to remove duplicates. */
#define DEFINE_GDB_SCRIPT(script_name) \
asm("\
.pushsection \".debug_gdb_scripts\", \"MS\",@progbits,1\n\
.byte 1\n\
.asciz \"" script_name "\"\n\
.popsection \n\
");
Then one can reference the macro in a header or source file like this:
DEFINE_GDB_SCRIPT ("my-app-scripts.py")
The script name may include directories if desired.
Note that loading of this script file also requires accordingly
configured `auto-load safe-path' (*note Auto-loading safe path::).
If the macro is put in a header, any application or library using
this header will get a reference to the specified script.

File: gdb.info, Node: Which flavor to choose?, Prev: dotdebug_gdb_scripts section, Up: Python Auto-loading
23.2.3.3 Which flavor to choose?
................................
Given the multiple ways of auto-loading Python scripts, it might not
always be clear which one to choose. This section provides some
guidance.
Benefits of the `-gdb.py' way:
* Can be used with file formats that don't support multiple sections.
* Ease of finding scripts for public libraries.
Scripts specified in the `.debug_gdb_scripts' section are searched
for in the source search path. For publicly installed libraries,
e.g., `libstdc++', there typically isn't a source directory in
which to find the script.
* Doesn't require source code additions.
Benefits of the `.debug_gdb_scripts' way:
* Works with static linking.
Scripts for libraries done the `-gdb.py' way require an objfile to
trigger their loading. When an application is statically linked
the only objfile available is the executable, and it is cumbersome
to attach all the scripts from all the input libraries to the
executable's `-gdb.py' script.
* Works with classes that are entirely inlined.
Some classes can be entirely inlined, and thus there may not be an
associated shared library to attach a `-gdb.py' script to.
* Scripts needn't be copied out of the source tree.
In some circumstances, apps can be built out of large collections
of internal libraries, and the build infrastructure necessary to
install the `-gdb.py' scripts in a place where GDB can find them is
cumbersome. It may be easier to specify the scripts in the
`.debug_gdb_scripts' section as relative paths, and add a path to
the top of the source tree to the source search path.

File: gdb.info, Node: Python modules, Prev: Python Auto-loading, Up: Python
23.2.4 Python modules
---------------------
GDB comes with several modules to assist writing Python code.
* Menu:
* gdb.printing:: Building and registering pretty-printers.
* gdb.types:: Utilities for working with types.
* gdb.prompt:: Utilities for prompt value substitution.

File: gdb.info, Node: gdb.printing, Next: gdb.types, Up: Python modules
23.2.4.1 gdb.printing
.....................
This module provides a collection of utilities for working with
pretty-printers.
`PrettyPrinter (NAME, SUBPRINTERS=None)'
This class specifies the API that makes `info pretty-printer',
`enable pretty-printer' and `disable pretty-printer' work.
Pretty-printers should generally inherit from this class.
`SubPrettyPrinter (NAME)'
For printers that handle multiple types, this class specifies the
corresponding API for the subprinters.
`RegexpCollectionPrettyPrinter (NAME)'
Utility class for handling multiple printers, all recognized via
regular expressions. *Note Writing a Pretty-Printer::, for an
example.
`FlagEnumerationPrinter (NAME)'
A pretty-printer which handles printing of `enum' values. Unlike
GDB's built-in `enum' printing, this printer attempts to work
properly when there is some overlap between the enumeration
constants. NAME is the name of the printer and also the name of
the `enum' type to look up.
`register_pretty_printer (OBJ, PRINTER, REPLACE=False)'
Register PRINTER with the pretty-printer list of OBJ. If REPLACE
is `True' then any existing copy of the printer is replaced.
Otherwise a `RuntimeError' exception is raised if a printer with
the same name already exists.

File: gdb.info, Node: gdb.types, Next: gdb.prompt, Prev: gdb.printing, Up: Python modules
23.2.4.2 gdb.types
..................
This module provides a collection of utilities for working with
`gdb.Types' objects.
`get_basic_type (TYPE)'
Return TYPE with const and volatile qualifiers stripped, and with
typedefs and C++ references converted to the underlying type.
C++ example:
typedef const int const_int;
const_int foo (3);
const_int& foo_ref (foo);
int main () { return 0; }
Then in gdb:
(gdb) start
(gdb) python import gdb.types
(gdb) python foo_ref = gdb.parse_and_eval("foo_ref")
(gdb) python print gdb.types.get_basic_type(foo_ref.type)
int
`has_field (TYPE, FIELD)'
Return `True' if TYPE, assumed to be a type with fields (e.g., a
structure or union), has field FIELD.
`make_enum_dict (ENUM_TYPE)'
Return a Python `dictionary' type produced from ENUM_TYPE.
`deep_items (TYPE)'
Returns a Python iterator similar to the standard
`gdb.Type.iteritems' method, except that the iterator returned by
`deep_items' will recursively traverse anonymous struct or union
fields. For example:
struct A
{
int a;
union {
int b0;
int b1;
};
};
Then in GDB:
(gdb) python import gdb.types
(gdb) python struct_a = gdb.lookup_type("struct A")
(gdb) python print struct_a.keys ()
{['a', '']}
(gdb) python print [k for k,v in gdb.types.deep_items(struct_a)]
{['a', 'b0', 'b1']}

File: gdb.info, Node: gdb.prompt, Prev: gdb.types, Up: Python modules
23.2.4.3 gdb.prompt
...................
This module provides a method for prompt value-substitution.
`substitute_prompt (STRING)'
Return STRING with escape sequences substituted by values. Some
escape sequences take arguments. You can specify arguments inside
"{}" immediately following the escape sequence.
The escape sequences you can pass to this function are:
`\\'
Substitute a backslash.
`\e'
Substitute an ESC character.
`\f'
Substitute the selected frame; an argument names a frame
parameter.
`\n'
Substitute a newline.
`\p'
Substitute a parameter's value; the argument names the
parameter.
`\r'
Substitute a carriage return.
`\t'
Substitute the selected thread; an argument names a thread
parameter.
`\v'
Substitute the version of GDB.
`\w'
Substitute the current working directory.
`\['
Begin a sequence of non-printing characters. These sequences
are typically used with the ESC character, and are not
counted in the string length. Example:
"\[\e[0;34m\](gdb)\[\e[0m\]" will return a blue-colored
"(gdb)" prompt where the length is five.
`\]'
End a sequence of non-printing characters.
For example:
substitute_prompt (``frame: \f,
print arguments: \p{print frame-arguments}'')
will return the string:
"frame: main, print arguments: scalars"

File: gdb.info, Node: Aliases, Prev: Python, Up: Extending GDB
23.3 Creating new spellings of existing commands
================================================
It is often useful to define alternate spellings of existing commands.
For example, if a new GDB command defined in Python has a long name to
type, it is handy to have an abbreviated version of it that involves
less typing.
GDB itself uses aliases. For example `s' is an alias of the `step'
command even though it is otherwise an ambiguous abbreviation of other
commands like `set' and `show'.
Aliases are also used to provide shortened or more common versions
of multi-word commands. For example, GDB provides the `tty' alias of
the `set inferior-tty' command.
You can define a new alias with the `alias' command.
`alias [-a] [--] ALIAS = COMMAND'
ALIAS specifies the name of the new alias. Each word of ALIAS must
consist of letters, numbers, dashes and underscores.
COMMAND specifies the name of an existing command that is being
aliased.
The `-a' option specifies that the new alias is an abbreviation of
the command. Abbreviations are not shown in command lists displayed by
the `help' command.
The `--' option specifies the end of options, and is useful when
ALIAS begins with a dash.
Here is a simple example showing how to make an abbreviation of a
command so that there is less to type. Suppose you were tired of
typing `disas', the current shortest unambiguous abbreviation of the
`disassemble' command and you wanted an even shorter version named `di'.
The following will accomplish this.
(gdb) alias -a di = disas
Note that aliases are different from user-defined commands. With a
user-defined command, you also need to write documentation for it with
the `document' command. An alias automatically picks up the
documentation of the existing command.
Here is an example where we make `elms' an abbreviation of
`elements' in the `set print elements' command. This is to show that
you can make an abbreviation of any part of a command.
(gdb) alias -a set print elms = set print elements
(gdb) alias -a show print elms = show print elements
(gdb) set p elms 20
(gdb) show p elms
Limit on string chars or array elements to print is 200.
Note that if you are defining an alias of a `set' command, and you
want to have an alias for the corresponding `show' command, then you
need to define the latter separately.
Unambiguously abbreviated commands are allowed in COMMAND and ALIAS,
just as they are normally.
(gdb) alias -a set pr elms = set p ele
Finally, here is an example showing the creation of a one word alias
for a more complex command. This creates alias `spe' of the command
`set print elements'.
(gdb) alias spe = set print elements
(gdb) spe 20

File: gdb.info, Node: Interpreters, Next: TUI, Prev: Extending GDB, Up: Top
24 Command Interpreters
***********************
GDB supports multiple command interpreters, and some command
infrastructure to allow users or user interface writers to switch
between interpreters or run commands in other interpreters.
GDB currently supports two command interpreters, the console
interpreter (sometimes called the command-line interpreter or CLI) and
the machine interface interpreter (or GDB/MI). This manual describes
both of these interfaces in great detail.
By default, GDB will start with the console interpreter. However,
the user may choose to start GDB with another interpreter by specifying
the `-i' or `--interpreter' startup options. Defined interpreters
include:
`console'
The traditional console or command-line interpreter. This is the
most often used interpreter with GDB. With no interpreter
specified at runtime, GDB will use this interpreter.
`mi'
The newest GDB/MI interface (currently `mi2'). Used primarily by
programs wishing to use GDB as a backend for a debugger GUI or an
IDE. For more information, see *Note The GDB/MI Interface: GDB/MI.
`mi2'
The current GDB/MI interface.
`mi1'
The GDB/MI interface included in GDB 5.1, 5.2, and 5.3.
The interpreter being used by GDB may not be dynamically switched at
runtime. Although possible, this could lead to a very precarious
situation. Consider an IDE using GDB/MI. If a user enters the command
"interpreter-set console" in a console view, GDB would switch to using
the console interpreter, rendering the IDE inoperable!
Although you may only choose a single interpreter at startup, you
may execute commands in any interpreter from the current interpreter
using the appropriate command. If you are running the console
interpreter, simply use the `interpreter-exec' command:
interpreter-exec mi "-data-list-register-names"
GDB/MI has a similar command, although it is only available in
versions of GDB which support GDB/MI version 2 (or greater).

File: gdb.info, Node: TUI, Next: Emacs, Prev: Interpreters, Up: Top
25 GDB Text User Interface
**************************
* Menu:
* TUI Overview:: TUI overview
* TUI Keys:: TUI key bindings
* TUI Single Key Mode:: TUI single key mode
* TUI Commands:: TUI-specific commands
* TUI Configuration:: TUI configuration variables
The GDB Text User Interface (TUI) is a terminal interface which uses
the `curses' library to show the source file, the assembly output, the
program registers and GDB commands in separate text windows. The TUI
mode is supported only on platforms where a suitable version of the
`curses' library is available.
The TUI mode is enabled by default when you invoke GDB as `gdb -tui'.
You can also switch in and out of TUI mode while GDB runs by using
various TUI commands and key bindings, such as `C-x C-a'. *Note TUI
Key Bindings: TUI Keys.

File: gdb.info, Node: TUI Overview, Next: TUI Keys, Up: TUI
25.1 TUI Overview
=================
In TUI mode, GDB can display several text windows:
_command_
This window is the GDB command window with the GDB prompt and the
GDB output. The GDB input is still managed using readline.
_source_
The source window shows the source file of the program. The
current line and active breakpoints are displayed in this window.
_assembly_
The assembly window shows the disassembly output of the program.
_register_
This window shows the processor registers. Registers are
highlighted when their values change.
The source and assembly windows show the current program position by
highlighting the current line and marking it with a `>' marker.
Breakpoints are indicated with two markers. The first marker indicates
the breakpoint type:
`B'
Breakpoint which was hit at least once.
`b'
Breakpoint which was never hit.
`H'
Hardware breakpoint which was hit at least once.
`h'
Hardware breakpoint which was never hit.
The second marker indicates whether the breakpoint is enabled or not:
`+'
Breakpoint is enabled.
`-'
Breakpoint is disabled.
The source, assembly and register windows are updated when the
current thread changes, when the frame changes, or when the program
counter changes.
These windows are not all visible at the same time. The command
window is always visible. The others can be arranged in several
layouts:
* source only,
* assembly only,
* source and assembly,
* source and registers, or
* assembly and registers.
A status line above the command window shows the following
information:
_target_
Indicates the current GDB target. (*note Specifying a Debugging
Target: Targets.).
_process_
Gives the current process or thread number. When no process is
being debugged, this field is set to `No process'.
_function_
Gives the current function name for the selected frame. The name
is demangled if demangling is turned on (*note Print Settings::).
When there is no symbol corresponding to the current program
counter, the string `??' is displayed.
_line_
Indicates the current line number for the selected frame. When
the current line number is not known, the string `??' is displayed.
_pc_
Indicates the current program counter address.

File: gdb.info, Node: TUI Keys, Next: TUI Single Key Mode, Prev: TUI Overview, Up: TUI
25.2 TUI Key Bindings
=====================
The TUI installs several key bindings in the readline keymaps (*note
Command Line Editing::). The following key bindings are installed for
both TUI mode and the GDB standard mode.
`C-x C-a'
`C-x a'
`C-x A'
Enter or leave the TUI mode. When leaving the TUI mode, the
curses window management stops and GDB operates using its standard
mode, writing on the terminal directly. When reentering the TUI
mode, control is given back to the curses windows. The screen is
then refreshed.
`C-x 1'
Use a TUI layout with only one window. The layout will either be
`source' or `assembly'. When the TUI mode is not active, it will
switch to the TUI mode.
Think of this key binding as the Emacs `C-x 1' binding.
`C-x 2'
Use a TUI layout with at least two windows. When the current
layout already has two windows, the next layout with two windows
is used. When a new layout is chosen, one window will always be
common to the previous layout and the new one.
Think of it as the Emacs `C-x 2' binding.
`C-x o'
Change the active window. The TUI associates several key bindings
(like scrolling and arrow keys) with the active window. This
command gives the focus to the next TUI window.
Think of it as the Emacs `C-x o' binding.
`C-x s'
Switch in and out of the TUI SingleKey mode that binds single keys
to GDB commands (*note TUI Single Key Mode::).
The following key bindings only work in the TUI mode:
<PgUp>
Scroll the active window one page up.
<PgDn>
Scroll the active window one page down.
<Up>
Scroll the active window one line up.
<Down>
Scroll the active window one line down.
<Left>
Scroll the active window one column left.
<Right>
Scroll the active window one column right.
`C-L'
Refresh the screen.
Because the arrow keys scroll the active window in the TUI mode, they
are not available for their normal use by readline unless the command
window has the focus. When another window is active, you must use
other readline key bindings such as `C-p', `C-n', `C-b' and `C-f' to
control the command window.

File: gdb.info, Node: TUI Single Key Mode, Next: TUI Commands, Prev: TUI Keys, Up: TUI
25.3 TUI Single Key Mode
========================
The TUI also provides a "SingleKey" mode, which binds several
frequently used GDB commands to single keys. Type `C-x s' to switch
into this mode, where the following key bindings are used:
`c'
continue
`d'
down
`f'
finish
`n'
next
`q'
exit the SingleKey mode.
`r'
run
`s'
step
`u'
up
`v'
info locals
`w'
where
Other keys temporarily switch to the GDB command prompt. The key
that was pressed is inserted in the editing buffer so that it is
possible to type most GDB commands without interaction with the TUI
SingleKey mode. Once the command is entered the TUI SingleKey mode is
restored. The only way to permanently leave this mode is by typing `q'
or `C-x s'.

File: gdb.info, Node: TUI Commands, Next: TUI Configuration, Prev: TUI Single Key Mode, Up: TUI
25.4 TUI-specific Commands
==========================
The TUI has specific commands to control the text windows. These
commands are always available, even when GDB is not in the TUI mode.
When GDB is in the standard mode, most of these commands will
automatically switch to the TUI mode.
Note that if GDB's `stdout' is not connected to a terminal, or GDB
has been started with the machine interface interpreter (*note The
GDB/MI Interface: GDB/MI.), most of these commands will fail with an
error, because it would not be possible or desirable to enable curses
window management.
`info win'
List and give the size of all displayed windows.
`layout next'
Display the next layout.
`layout prev'
Display the previous layout.
`layout src'
Display the source window only.
`layout asm'
Display the assembly window only.
`layout split'
Display the source and assembly window.
`layout regs'
Display the register window together with the source or assembly
window.
`focus next'
Make the next window active for scrolling.
`focus prev'
Make the previous window active for scrolling.
`focus src'
Make the source window active for scrolling.
`focus asm'
Make the assembly window active for scrolling.
`focus regs'
Make the register window active for scrolling.
`focus cmd'
Make the command window active for scrolling.
`refresh'
Refresh the screen. This is similar to typing `C-L'.
`tui reg float'
Show the floating point registers in the register window.
`tui reg general'
Show the general registers in the register window.
`tui reg next'
Show the next register group. The list of register groups as well
as their order is target specific. The predefined register groups
are the following: `general', `float', `system', `vector', `all',
`save', `restore'.
`tui reg system'
Show the system registers in the register window.
`update'
Update the source window and the current execution point.
`winheight NAME +COUNT'
`winheight NAME -COUNT'
Change the height of the window NAME by COUNT lines. Positive
counts increase the height, while negative counts decrease it.
`tabset NCHARS'
Set the width of tab stops to be NCHARS characters.

File: gdb.info, Node: TUI Configuration, Prev: TUI Commands, Up: TUI
25.5 TUI Configuration Variables
================================
Several configuration variables control the appearance of TUI windows.
`set tui border-kind KIND'
Select the border appearance for the source, assembly and register
windows. The possible values are the following:
`space'
Use a space character to draw the border.
`ascii'
Use ASCII characters `+', `-' and `|' to draw the border.
`acs'
Use the Alternate Character Set to draw the border. The
border is drawn using character line graphics if the terminal
supports them.
`set tui border-mode MODE'
`set tui active-border-mode MODE'
Select the display attributes for the borders of the inactive
windows or the active window. The MODE can be one of the
following:
`normal'
Use normal attributes to display the border.
`standout'
Use standout mode.
`reverse'
Use reverse video mode.
`half'
Use half bright mode.
`half-standout'
Use half bright and standout mode.
`bold'
Use extra bright or bold mode.
`bold-standout'
Use extra bright or bold and standout mode.

File: gdb.info, Node: Emacs, Next: GDB/MI, Prev: TUI, Up: Top
26 Using GDB under GNU Emacs
****************************
A special interface allows you to use GNU Emacs to view (and edit) the
source files for the program you are debugging with GDB.
To use this interface, use the command `M-x gdb' in Emacs. Give the
executable file you want to debug as an argument. This command starts
GDB as a subprocess of Emacs, with input and output through a newly
created Emacs buffer.
Running GDB under Emacs can be just like running GDB normally except
for two things:
* All "terminal" input and output goes through an Emacs buffer,
called the GUD buffer.
This applies both to GDB commands and their output, and to the
input and output done by the program you are debugging.
This is useful because it means that you can copy the text of
previous commands and input them again; you can even use parts of
the output in this way.
All the facilities of Emacs' Shell mode are available for
interacting with your program. In particular, you can send
signals the usual way--for example, `C-c C-c' for an interrupt,
`C-c C-z' for a stop.
* GDB displays source code through Emacs.
Each time GDB displays a stack frame, Emacs automatically finds the
source file for that frame and puts an arrow (`=>') at the left
margin of the current line. Emacs uses a separate buffer for
source display, and splits the screen to show both your GDB session
and the source.
Explicit GDB `list' or search commands still produce output as
usual, but you probably have no reason to use them from Emacs.
We call this "text command mode". Emacs 22.1, and later, also uses
a graphical mode, enabled by default, which provides further buffers
that can control the execution and describe the state of your program.
*Note GDB Graphical Interface: (Emacs)GDB Graphical Interface.
If you specify an absolute file name when prompted for the `M-x gdb'
argument, then Emacs sets your current working directory to where your
program resides. If you only specify the file name, then Emacs sets
your current working directory to the directory associated with the
previous buffer. In this case, GDB may find your program by searching
your environment's `PATH' variable, but on some operating systems it
might not find the source. So, although the GDB input and output
session proceeds normally, the auxiliary buffer does not display the
current source and line of execution.
The initial working directory of GDB is printed on the top line of
the GUD buffer and this serves as a default for the commands that
specify files for GDB to operate on. *Note Commands to Specify Files:
Files.
By default, `M-x gdb' calls the program called `gdb'. If you need
to call GDB by a different name (for example, if you keep several
configurations around, with different names) you can customize the
Emacs variable `gud-gdb-command-name' to run the one you want.
In the GUD buffer, you can use these special Emacs commands in
addition to the standard Shell mode commands:
`C-h m'
Describe the features of Emacs' GUD Mode.
`C-c C-s'
Execute to another source line, like the GDB `step' command; also
update the display window to show the current file and location.
`C-c C-n'
Execute to next source line in this function, skipping all function
calls, like the GDB `next' command. Then update the display window
to show the current file and location.
`C-c C-i'
Execute one instruction, like the GDB `stepi' command; update
display window accordingly.
`C-c C-f'
Execute until exit from the selected stack frame, like the GDB
`finish' command.
`C-c C-r'
Continue execution of your program, like the GDB `continue'
command.
`C-c <'
Go up the number of frames indicated by the numeric argument
(*note Numeric Arguments: (Emacs)Arguments.), like the GDB `up'
command.
`C-c >'
Go down the number of frames indicated by the numeric argument,
like the GDB `down' command.
In any source file, the Emacs command `C-x <SPC>' (`gud-break')
tells GDB to set a breakpoint on the source line point is on.
In text command mode, if you type `M-x speedbar', Emacs displays a
separate frame which shows a backtrace when the GUD buffer is current.
Move point to any frame in the stack and type <RET> to make it become
the current frame and display the associated source in the source
buffer. Alternatively, click `Mouse-2' to make the selected frame
become the current one. In graphical mode, the speedbar displays watch
expressions.
If you accidentally delete the source-display buffer, an easy way to
get it back is to type the command `f' in the GDB buffer, to request a
frame display; when you run under Emacs, this recreates the source
buffer if necessary to show you the context of the current frame.
The source files displayed in Emacs are in ordinary Emacs buffers
which are visiting the source files in the usual way. You can edit the
files with these buffers if you wish; but keep in mind that GDB
communicates with Emacs in terms of line numbers. If you add or delete
lines from the text, the line numbers that GDB knows cease to
correspond properly with the code.
A more detailed description of Emacs' interaction with GDB is given
in the Emacs manual (*note Debuggers: (Emacs)Debuggers.).

File: gdb.info, Node: GDB/MI, Next: Annotations, Prev: Emacs, Up: Top
27 The GDB/MI Interface
***********************
Function and Purpose
====================
GDB/MI is a line based machine oriented text interface to GDB and is
activated by specifying using the `--interpreter' command line option
(*note Mode Options::). It is specifically intended to support the
development of systems which use the debugger as just one small
component of a larger system.
This chapter is a specification of the GDB/MI interface. It is
written in the form of a reference manual.
Note that GDB/MI is still under construction, so some of the
features described below are incomplete and subject to change (*note
GDB/MI Development and Front Ends: GDB/MI Development and Front Ends.).
Notation and Terminology
========================
This chapter uses the following notation:
* `|' separates two alternatives.
* `[ SOMETHING ]' indicates that SOMETHING is optional: it may or
may not be given.
* `( GROUP )*' means that GROUP inside the parentheses may repeat
zero or more times.
* `( GROUP )+' means that GROUP inside the parentheses may repeat
one or more times.
* `"STRING"' means a literal STRING.
* Menu:
* GDB/MI General Design::
* GDB/MI Command Syntax::
* GDB/MI Compatibility with CLI::
* GDB/MI Development and Front Ends::
* GDB/MI Output Records::
* GDB/MI Simple Examples::
* GDB/MI Command Description Format::
* GDB/MI Breakpoint Commands::
* GDB/MI Program Context::
* GDB/MI Thread Commands::
* GDB/MI Ada Tasking Commands::
* GDB/MI Program Execution::
* GDB/MI Stack Manipulation::
* GDB/MI Variable Objects::
* GDB/MI Data Manipulation::
* GDB/MI Tracepoint Commands::
* GDB/MI Symbol Query::
* GDB/MI File Commands::
* GDB/MI Target Manipulation::
* GDB/MI File Transfer Commands::
* GDB/MI Miscellaneous Commands::

File: gdb.info, Node: GDB/MI General Design, Next: GDB/MI Command Syntax, Up: GDB/MI
27.1 GDB/MI General Design
==========================
Interaction of a GDB/MI frontend with GDB involves three
parts--commands sent to GDB, responses to those commands and
notifications. Each command results in exactly one response,
indicating either successful completion of the command, or an error.
For the commands that do not resume the target, the response contains
the requested information. For the commands that resume the target, the
response only indicates whether the target was successfully resumed.
Notifications is the mechanism for reporting changes in the state of the
target, or in GDB state, that cannot conveniently be associated with a
command and reported as part of that command response.
The important examples of notifications are:
* Exec notifications. These are used to report changes in target
state--when a target is resumed, or stopped. It would not be
feasible to include this information in response of resuming
commands, because one resume commands can result in multiple
events in different threads. Also, quite some time may pass
before any event happens in the target, while a frontend needs to
know whether the resuming command itself was successfully executed.
* Console output, and status notifications. Console output
notifications are used to report output of CLI commands, as well as
diagnostics for other commands. Status notifications are used to
report the progress of a long-running operation. Naturally,
including this information in command response would mean no
output is produced until the command is finished, which is
undesirable.
* General notifications. Commands may have various side effects on
the GDB or target state beyond their official purpose. For
example, a command may change the selected thread. Although such
changes can be included in command response, using notification
allows for more orthogonal frontend design.
There's no guarantee that whenever an MI command reports an error,
GDB or the target are in any specific state, and especially, the state
is not reverted to the state before the MI command was processed.
Therefore, whenever an MI command results in an error, we recommend
that the frontend refreshes all the information shown in the user
interface.
* Menu:
* Context management::
* Asynchronous and non-stop modes::
* Thread groups::

File: gdb.info, Node: Context management, Next: Asynchronous and non-stop modes, Up: GDB/MI General Design
27.1.1 Context management
-------------------------
In most cases when GDB accesses the target, this access is done in
context of a specific thread and frame (*note Frames::). Often, even
when accessing global data, the target requires that a thread be
specified. The CLI interface maintains the selected thread and frame,
and supplies them to target on each command. This is convenient,
because a command line user would not want to specify that information
explicitly on each command, and because user interacts with GDB via a
single terminal, so no confusion is possible as to what thread and
frame are the current ones.
In the case of MI, the concept of selected thread and frame is less
useful. First, a frontend can easily remember this information itself.
Second, a graphical frontend can have more than one window, each one
used for debugging a different thread, and the frontend might want to
access additional threads for internal purposes. This increases the
risk that by relying on implicitly selected thread, the frontend may be
operating on a wrong one. Therefore, each MI command should explicitly
specify which thread and frame to operate on. To make it possible,
each MI command accepts the `--thread' and `--frame' options, the value
to each is GDB identifier for thread and frame to operate on.
Usually, each top-level window in a frontend allows the user to
select a thread and a frame, and remembers the user selection for
further operations. However, in some cases GDB may suggest that the
current thread be changed. For example, when stopping on a breakpoint
it is reasonable to switch to the thread where breakpoint is hit. For
another example, if the user issues the CLI `thread' command via the
frontend, it is desirable to change the frontend's selected thread to
the one specified by user. GDB communicates the suggestion to change
current thread using the `=thread-selected' notification. No such
notification is available for the selected frame at the moment.
Note that historically, MI shares the selected thread with CLI, so
frontends used the `-thread-select' to execute commands in the right
context. However, getting this to work right is cumbersome. The
simplest way is for frontend to emit `-thread-select' command before
every command. This doubles the number of commands that need to be
sent. The alternative approach is to suppress `-thread-select' if the
selected thread in GDB is supposed to be identical to the thread the
frontend wants to operate on. However, getting this optimization right
can be tricky. In particular, if the frontend sends several commands
to GDB, and one of the commands changes the selected thread, then the
behaviour of subsequent commands will change. So, a frontend should
either wait for response from such problematic commands, or explicitly
add `-thread-select' for all subsequent commands. No frontend is known
to do this exactly right, so it is suggested to just always pass the
`--thread' and `--frame' options.

File: gdb.info, Node: Asynchronous and non-stop modes, Next: Thread groups, Prev: Context management, Up: GDB/MI General Design
27.1.2 Asynchronous command execution and non-stop mode
-------------------------------------------------------
On some targets, GDB is capable of processing MI commands even while
the target is running. This is called "asynchronous command execution"
(*note Background Execution::). The frontend may specify a preferrence
for asynchronous execution using the `-gdb-set target-async 1' command,
which should be emitted before either running the executable or
attaching to the target. After the frontend has started the executable
or attached to the target, it can find if asynchronous execution is
enabled using the `-list-target-features' command.
Even if GDB can accept a command while target is running, many
commands that access the target do not work when the target is running.
Therefore, asynchronous command execution is most useful when combined
with non-stop mode (*note Non-Stop Mode::). Then, it is possible to
examine the state of one thread, while other threads are running.
When a given thread is running, MI commands that try to access the
target in the context of that thread may not work, or may work only on
some targets. In particular, commands that try to operate on thread's
stack will not work, on any target. Commands that read memory, or
modify breakpoints, may work or not work, depending on the target. Note
that even commands that operate on global state, such as `print',
`set', and breakpoint commands, still access the target in the context
of a specific thread, so frontend should try to find a stopped thread
and perform the operation on that thread (using the `--thread' option).
Which commands will work in the context of a running thread is
highly target dependent. However, the two commands `-exec-interrupt',
to stop a thread, and `-thread-info', to find the state of a thread,
will always work.

File: gdb.info, Node: Thread groups, Prev: Asynchronous and non-stop modes, Up: GDB/MI General Design
27.1.3 Thread groups
--------------------
GDB may be used to debug several processes at the same time. On some
platfroms, GDB may support debugging of several hardware systems, each
one having several cores with several different processes running on
each core. This section describes the MI mechanism to support such
debugging scenarios.
The key observation is that regardless of the structure of the
target, MI can have a global list of threads, because most commands that
accept the `--thread' option do not need to know what process that
thread belongs to. Therefore, it is not necessary to introduce neither
additional `--process' option, nor an notion of the current process in
the MI interface. The only strictly new feature that is required is
the ability to find how the threads are grouped into processes.
To allow the user to discover such grouping, and to support arbitrary
hierarchy of machines/cores/processes, MI introduces the concept of a
"thread group". Thread group is a collection of threads and other
thread groups. A thread group always has a string identifier, a type,
and may have additional attributes specific to the type. A new
command, `-list-thread-groups', returns the list of top-level thread
groups, which correspond to processes that GDB is debugging at the
moment. By passing an identifier of a thread group to the
`-list-thread-groups' command, it is possible to obtain the members of
specific thread group.
To allow the user to easily discover processes, and other objects, he
wishes to debug, a concept of "available thread group" is introduced.
Available thread group is an thread group that GDB is not debugging,
but that can be attached to, using the `-target-attach' command. The
list of available top-level thread groups can be obtained using
`-list-thread-groups --available'. In general, the content of a thread
group may be only retrieved only after attaching to that thread group.
Thread groups are related to inferiors (*note Inferiors and
Programs::). Each inferior corresponds to a thread group of a special
type `process', and some additional operations are permitted on such
thread groups.

File: gdb.info, Node: GDB/MI Command Syntax, Next: GDB/MI Compatibility with CLI, Prev: GDB/MI General Design, Up: GDB/MI
27.2 GDB/MI Command Syntax
==========================
* Menu:
* GDB/MI Input Syntax::
* GDB/MI Output Syntax::

File: gdb.info, Node: GDB/MI Input Syntax, Next: GDB/MI Output Syntax, Up: GDB/MI Command Syntax
27.2.1 GDB/MI Input Syntax
--------------------------
`COMMAND ==>'
`CLI-COMMAND | MI-COMMAND'
`CLI-COMMAND ==>'
`[ TOKEN ] CLI-COMMAND NL', where CLI-COMMAND is any existing GDB
CLI command.
`MI-COMMAND ==>'
`[ TOKEN ] "-" OPERATION ( " " OPTION )* `[' " --" `]' ( " "
PARAMETER )* NL'
`TOKEN ==>'
"any sequence of digits"
`OPTION ==>'
`"-" PARAMETER [ " " PARAMETER ]'
`PARAMETER ==>'
`NON-BLANK-SEQUENCE | C-STRING'
`OPERATION ==>'
_any of the operations described in this chapter_
`NON-BLANK-SEQUENCE ==>'
_anything, provided it doesn't contain special characters such as
"-", NL, """ and of course " "_
`C-STRING ==>'
`""" SEVEN-BIT-ISO-C-STRING-CONTENT """'
`NL ==>'
`CR | CR-LF'
Notes:
* The CLI commands are still handled by the MI interpreter; their
output is described below.
* The `TOKEN', when present, is passed back when the command
finishes.
* Some MI commands accept optional arguments as part of the parameter
list. Each option is identified by a leading `-' (dash) and may be
followed by an optional argument parameter. Options occur first
in the parameter list and can be delimited from normal parameters
using `--' (this is useful when some parameters begin with a dash).
Pragmatics:
* We want easy access to the existing CLI syntax (for debugging).
* We want it to be easy to spot a MI operation.

File: gdb.info, Node: GDB/MI Output Syntax, Prev: GDB/MI Input Syntax, Up: GDB/MI Command Syntax
27.2.2 GDB/MI Output Syntax
---------------------------
The output from GDB/MI consists of zero or more out-of-band records
followed, optionally, by a single result record. This result record is
for the most recent command. The sequence of output records is
terminated by `(gdb)'.
If an input command was prefixed with a `TOKEN' then the
corresponding output for that command will also be prefixed by that same
TOKEN.
`OUTPUT ==>'
`( OUT-OF-BAND-RECORD )* [ RESULT-RECORD ] "(gdb)" NL'
`RESULT-RECORD ==>'
` [ TOKEN ] "^" RESULT-CLASS ( "," RESULT )* NL'
`OUT-OF-BAND-RECORD ==>'
`ASYNC-RECORD | STREAM-RECORD'
`ASYNC-RECORD ==>'
`EXEC-ASYNC-OUTPUT | STATUS-ASYNC-OUTPUT | NOTIFY-ASYNC-OUTPUT'
`EXEC-ASYNC-OUTPUT ==>'
`[ TOKEN ] "*" ASYNC-OUTPUT'
`STATUS-ASYNC-OUTPUT ==>'
`[ TOKEN ] "+" ASYNC-OUTPUT'
`NOTIFY-ASYNC-OUTPUT ==>'
`[ TOKEN ] "=" ASYNC-OUTPUT'
`ASYNC-OUTPUT ==>'
`ASYNC-CLASS ( "," RESULT )* NL'
`RESULT-CLASS ==>'
`"done" | "running" | "connected" | "error" | "exit"'
`ASYNC-CLASS ==>'
`"stopped" | OTHERS' (where OTHERS will be added depending on the
needs--this is still in development).
`RESULT ==>'
` VARIABLE "=" VALUE'
`VARIABLE ==>'
` STRING '
`VALUE ==>'
` CONST | TUPLE | LIST '
`CONST ==>'
`C-STRING'
`TUPLE ==>'
` "{}" | "{" RESULT ( "," RESULT )* "}" '
`LIST ==>'
` "[]" | "[" VALUE ( "," VALUE )* "]" | "[" RESULT ( "," RESULT )*
"]" '
`STREAM-RECORD ==>'
`CONSOLE-STREAM-OUTPUT | TARGET-STREAM-OUTPUT | LOG-STREAM-OUTPUT'
`CONSOLE-STREAM-OUTPUT ==>'
`"~" C-STRING'
`TARGET-STREAM-OUTPUT ==>'
`"@" C-STRING'
`LOG-STREAM-OUTPUT ==>'
`"&" C-STRING'
`NL ==>'
`CR | CR-LF'
`TOKEN ==>'
_any sequence of digits_.
Notes:
* All output sequences end in a single line containing a period.
* The `TOKEN' is from the corresponding request. Note that for all
async output, while the token is allowed by the grammar and may be
output by future versions of GDB for select async output messages,
it is generally omitted. Frontends should treat all async output
as reporting general changes in the state of the target and there
should be no need to associate async output to any prior command.
* STATUS-ASYNC-OUTPUT contains on-going status information about the
progress of a slow operation. It can be discarded. All status
output is prefixed by `+'.
* EXEC-ASYNC-OUTPUT contains asynchronous state change on the target
(stopped, started, disappeared). All async output is prefixed by
`*'.
* NOTIFY-ASYNC-OUTPUT contains supplementary information that the
client should handle (e.g., a new breakpoint information). All
notify output is prefixed by `='.
* CONSOLE-STREAM-OUTPUT is output that should be displayed as is in
the console. It is the textual response to a CLI command. All
the console output is prefixed by `~'.
* TARGET-STREAM-OUTPUT is the output produced by the target program.
All the target output is prefixed by `@'.
* LOG-STREAM-OUTPUT is output text coming from GDB's internals, for
instance messages that should be displayed as part of an error
log. All the log output is prefixed by `&'.
* New GDB/MI commands should only output LISTS containing VALUES.
*Note GDB/MI Stream Records: GDB/MI Stream Records, for more details
about the various output records.

File: gdb.info, Node: GDB/MI Compatibility with CLI, Next: GDB/MI Development and Front Ends, Prev: GDB/MI Command Syntax, Up: GDB/MI
27.3 GDB/MI Compatibility with CLI
==================================
For the developers convenience CLI commands can be entered directly,
but there may be some unexpected behaviour. For example, commands that
query the user will behave as if the user replied yes, breakpoint
command lists are not executed and some CLI commands, such as `if',
`when' and `define', prompt for further input with `>', which is not
valid MI output.
This feature may be removed at some stage in the future and it is
recommended that front ends use the `-interpreter-exec' command (*note
-interpreter-exec::).

File: gdb.info, Node: GDB/MI Development and Front Ends, Next: GDB/MI Output Records, Prev: GDB/MI Compatibility with CLI, Up: GDB/MI
27.4 GDB/MI Development and Front Ends
======================================
The application which takes the MI output and presents the state of the
program being debugged to the user is called a "front end".
Although GDB/MI is still incomplete, it is currently being used by a
variety of front ends to GDB. This makes it difficult to introduce new
functionality without breaking existing usage. This section tries to
minimize the problems by describing how the protocol might change.
Some changes in MI need not break a carefully designed front end, and
for these the MI version will remain unchanged. The following is a
list of changes that may occur within one level, so front ends should
parse MI output in a way that can handle them:
* New MI commands may be added.
* New fields may be added to the output of any MI command.
* The range of values for fields with specified values, e.g.,
`in_scope' (*note -var-update::) may be extended.
If the changes are likely to break front ends, the MI version level
will be increased by one. This will allow the front end to parse the
output according to the MI version. Apart from mi0, new versions of
GDB will not support old versions of MI and it will be the
responsibility of the front end to work with the new one.
The best way to avoid unexpected changes in MI that might break your
front end is to make your project known to GDB developers and follow
development on <gdb@sourceware.org> and <gdb-patches@sourceware.org>.

File: gdb.info, Node: GDB/MI Output Records, Next: GDB/MI Simple Examples, Prev: GDB/MI Development and Front Ends, Up: GDB/MI
27.5 GDB/MI Output Records
==========================
* Menu:
* GDB/MI Result Records::
* GDB/MI Stream Records::
* GDB/MI Async Records::
* GDB/MI Frame Information::
* GDB/MI Thread Information::
* GDB/MI Ada Exception Information::

File: gdb.info, Node: GDB/MI Result Records, Next: GDB/MI Stream Records, Up: GDB/MI Output Records
27.5.1 GDB/MI Result Records
----------------------------
In addition to a number of out-of-band notifications, the response to a
GDB/MI command includes one of the following result indications:
`"^done" [ "," RESULTS ]'
The synchronous operation was successful, `RESULTS' are the return
values.
`"^running"'
This result record is equivalent to `^done'. Historically, it was
output instead of `^done' if the command has resumed the target.
This behaviour is maintained for backward compatibility, but all
frontends should treat `^done' and `^running' identically and rely
on the `*running' output record to determine which threads are
resumed.
`"^connected"'
GDB has connected to a remote target.
`"^error" "," C-STRING'
The operation failed. The `C-STRING' contains the corresponding
error message.
`"^exit"'
GDB has terminated.

File: gdb.info, Node: GDB/MI Stream Records, Next: GDB/MI Async Records, Prev: GDB/MI Result Records, Up: GDB/MI Output Records
27.5.2 GDB/MI Stream Records
----------------------------
GDB internally maintains a number of output streams: the console, the
target, and the log. The output intended for each of these streams is
funneled through the GDB/MI interface using "stream records".
Each stream record begins with a unique "prefix character" which
identifies its stream (*note GDB/MI Output Syntax: GDB/MI Output
Syntax.). In addition to the prefix, each stream record contains a
`STRING-OUTPUT'. This is either raw text (with an implicit new line)
or a quoted C string (which does not contain an implicit newline).
`"~" STRING-OUTPUT'
The console output stream contains text that should be displayed
in the CLI console window. It contains the textual responses to
CLI commands.
`"@" STRING-OUTPUT'
The target output stream contains any textual output from the
running target. This is only present when GDB's event loop is
truly asynchronous, which is currently only the case for remote
targets.
`"&" STRING-OUTPUT'
The log stream contains debugging messages being produced by GDB's
internals.

File: gdb.info, Node: GDB/MI Async Records, Next: GDB/MI Frame Information, Prev: GDB/MI Stream Records, Up: GDB/MI Output Records
27.5.3 GDB/MI Async Records
---------------------------
"Async" records are used to notify the GDB/MI client of additional
changes that have occurred. Those changes can either be a consequence
of GDB/MI commands (e.g., a breakpoint modified) or a result of target
activity (e.g., target stopped).
The following is the list of possible async records:
`*running,thread-id="THREAD"'
The target is now running. The THREAD field tells which specific
thread is now running, and can be `all' if all threads are
running. The frontend should assume that no interaction with a
running thread is possible after this notification is produced.
The frontend should not assume that this notification is output
only once for any command. GDB may emit this notification several
times, either for different threads, because it cannot resume all
threads together, or even for a single thread, if the thread must
be stepped though some code before letting it run freely.
`*stopped,reason="REASON",thread-id="ID",stopped-threads="STOPPED",core="CORE"'
The target has stopped. The REASON field can have one of the
following values:
`breakpoint-hit'
A breakpoint was reached.
`watchpoint-trigger'
A watchpoint was triggered.
`read-watchpoint-trigger'
A read watchpoint was triggered.
`access-watchpoint-trigger'
An access watchpoint was triggered.
`function-finished'
An -exec-finish or similar CLI command was accomplished.
`location-reached'
An -exec-until or similar CLI command was accomplished.
`watchpoint-scope'
A watchpoint has gone out of scope.
`end-stepping-range'
An -exec-next, -exec-next-instruction, -exec-step,
-exec-step-instruction or similar CLI command was
accomplished.
`exited-signalled'
The inferior exited because of a signal.
`exited'
The inferior exited.
`exited-normally'
The inferior exited normally.
`signal-received'
A signal was received by the inferior.
`solib-event'
The inferior has stopped due to a library being loaded or
unloaded. This can happen when `stop-on-solib-events' (*note
Files::) is set or when a `catch load' or `catch unload'
catchpoint is in use (*note Set Catchpoints::).
`fork'
The inferior has forked. This is reported when `catch fork'
(*note Set Catchpoints::) has been used.
`vfork'
The inferior has vforked. This is reported in when `catch
vfork' (*note Set Catchpoints::) has been used.
`syscall-entry'
The inferior entered a system call. This is reported when
`catch syscall' (*note Set Catchpoints::) has been used.
`syscall-entry'
The inferior returned from a system call. This is reported
when `catch syscall' (*note Set Catchpoints::) has been used.
`exec'
The inferior called `exec'. This is reported when `catch
exec' (*note Set Catchpoints::) has been used.
The ID field identifies the thread that directly caused the stop -
for example by hitting a breakpoint. Depending on whether all-stop
mode is in effect (*note All-Stop Mode::), GDB may either stop all
threads, or only the thread that directly triggered the stop. If
all threads are stopped, the STOPPED field will have the value of
`"all"'. Otherwise, the value of the STOPPED field will be a list
of thread identifiers. Presently, this list will always include a
single thread, but frontend should be prepared to see several
threads in the list. The CORE field reports the processor core on
which the stop event has happened. This field may be absent if
such information is not available.
`=thread-group-added,id="ID"'
`=thread-group-removed,id="ID"'
A thread group was either added or removed. The ID field contains
the GDB identifier of the thread group. When a thread group is
added, it generally might not be associated with a running
process. When a thread group is removed, its id becomes invalid
and cannot be used in any way.
`=thread-group-started,id="ID",pid="PID"'
A thread group became associated with a running program, either
because the program was just started or the thread group was
attached to a program. The ID field contains the GDB identifier
of the thread group. The PID field contains process identifier,
specific to the operating system.
`=thread-group-exited,id="ID"[,exit-code="CODE"]'
A thread group is no longer associated with a running program,
either because the program has exited, or because it was detached
from. The ID field contains the GDB identifier of the thread
group. CODE is the exit code of the inferior; it exists only when
the inferior exited with some code.
`=thread-created,id="ID",group-id="GID"'
`=thread-exited,id="ID",group-id="GID"'
A thread either was created, or has exited. The ID field contains
the GDB identifier of the thread. The GID field identifies the
thread group this thread belongs to.
`=thread-selected,id="ID"'
Informs that the selected thread was changed as result of the last
command. This notification is not emitted as result of
`-thread-select' command but is emitted whenever an MI command
that is not documented to change the selected thread actually
changes it. In particular, invoking, directly or indirectly (via
user-defined command), the CLI `thread' command, will generate
this notification.
We suggest that in response to this notification, front ends
highlight the selected thread and cause subsequent commands to
apply to that thread.
`=library-loaded,...'
Reports that a new library file was loaded by the program. This
notification has 4 fields--ID, TARGET-NAME, HOST-NAME, and
SYMBOLS-LOADED. The ID field is an opaque identifier of the
library. For remote debugging case, TARGET-NAME and HOST-NAME
fields give the name of the library file on the target, and on the
host respectively. For native debugging, both those fields have
the same value. The SYMBOLS-LOADED field is emitted only for
backward compatibility and should not be relied on to convey any
useful information. The THREAD-GROUP field, if present, specifies
the id of the thread group in whose context the library was
loaded. If the field is absent, it means the library was loaded
in the context of all present thread groups.
`=library-unloaded,...'
Reports that a library was unloaded by the program. This
notification has 3 fields--ID, TARGET-NAME and HOST-NAME with the
same meaning as for the `=library-loaded' notification. The
THREAD-GROUP field, if present, specifies the id of the thread
group in whose context the library was unloaded. If the field is
absent, it means the library was unloaded in the context of all
present thread groups.
`=breakpoint-created,bkpt={...}'
`=breakpoint-modified,bkpt={...}'
`=breakpoint-deleted,bkpt={...}'
Reports that a breakpoint was created, modified, or deleted,
respectively. Only user-visible breakpoints are reported to the MI
user.
The BKPT argument is of the same form as returned by the various
breakpoint commands; *Note GDB/MI Breakpoint Commands::.
Note that if a breakpoint is emitted in the result record of a
command, then it will not also be emitted in an async record.

File: gdb.info, Node: GDB/MI Frame Information, Next: GDB/MI Thread Information, Prev: GDB/MI Async Records, Up: GDB/MI Output Records
27.5.4 GDB/MI Frame Information
-------------------------------
Response from many MI commands includes an information about stack
frame. This information is a tuple that may have the following fields:
`level'
The level of the stack frame. The innermost frame has the level of
zero. This field is always present.
`func'
The name of the function corresponding to the frame. This field
may be absent if GDB is unable to determine the function name.
`addr'
The code address for the frame. This field is always present.
`file'
The name of the source files that correspond to the frame's code
address. This field may be absent.
`line'
The source line corresponding to the frames' code address. This
field may be absent.
`from'
The name of the binary file (either executable or shared library)
the corresponds to the frame's code address. This field may be
absent.

File: gdb.info, Node: GDB/MI Thread Information, Next: GDB/MI Ada Exception Information, Prev: GDB/MI Frame Information, Up: GDB/MI Output Records
27.5.5 GDB/MI Thread Information
--------------------------------
Whenever GDB has to report an information about a thread, it uses a
tuple with the following fields:
`id'
The numeric id assigned to the thread by GDB. This field is
always present.
`target-id'
Target-specific string identifying the thread. This field is
always present.
`details'
Additional information about the thread provided by the target.
It is supposed to be human-readable and not interpreted by the
frontend. This field is optional.
`state'
Either `stopped' or `running', depending on whether the thread is
presently running. This field is always present.
`core'
The value of this field is an integer number of the processor core
the thread was last seen on. This field is optional.

File: gdb.info, Node: GDB/MI Ada Exception Information, Prev: GDB/MI Thread Information, Up: GDB/MI Output Records
27.5.6 GDB/MI Ada Exception Information
---------------------------------------
Whenever a `*stopped' record is emitted because the program stopped
after hitting an exception catchpoint (*note Set Catchpoints::), GDB
provides the name of the exception that was raised via the
`exception-name' field.

File: gdb.info, Node: GDB/MI Simple Examples, Next: GDB/MI Command Description Format, Prev: GDB/MI Output Records, Up: GDB/MI
27.6 Simple Examples of GDB/MI Interaction
==========================================
This subsection presents several simple examples of interaction using
the GDB/MI interface. In these examples, `->' means that the following
line is passed to GDB/MI as input, while `<-' means the output received
from GDB/MI.
Note the line breaks shown in the examples are here only for
readability, they don't appear in the real output.
Setting a Breakpoint
--------------------
Setting a breakpoint generates synchronous output which contains
detailed information of the breakpoint.
-> -break-insert main
<- ^done,bkpt={number="1",type="breakpoint",disp="keep",
enabled="y",addr="0x08048564",func="main",file="myprog.c",
fullname="/home/nickrob/myprog.c",line="68",times="0"}
<- (gdb)
Program Execution
-----------------
Program execution generates asynchronous records and MI gives the
reason that execution stopped.
-> -exec-run
<- ^running
<- (gdb)
<- *stopped,reason="breakpoint-hit",disp="keep",bkptno="1",thread-id="0",
frame={addr="0x08048564",func="main",
args=[{name="argc",value="1"},{name="argv",value="0xbfc4d4d4"}],
file="myprog.c",fullname="/home/nickrob/myprog.c",line="68"}
<- (gdb)
-> -exec-continue
<- ^running
<- (gdb)
<- *stopped,reason="exited-normally"
<- (gdb)
Quitting GDB
------------
Quitting GDB just prints the result class `^exit'.
-> (gdb)
<- -gdb-exit
<- ^exit
Please note that `^exit' is printed immediately, but it might take
some time for GDB to actually exit. During that time, GDB performs
necessary cleanups, including killing programs being debugged or
disconnecting from debug hardware, so the frontend should wait till GDB
exits and should only forcibly kill GDB if it fails to exit in
reasonable time.
A Bad Command
-------------
Here's what happens if you pass a non-existent command:
-> -rubbish
<- ^error,msg="Undefined MI command: rubbish"
<- (gdb)

File: gdb.info, Node: GDB/MI Command Description Format, Next: GDB/MI Breakpoint Commands, Prev: GDB/MI Simple Examples, Up: GDB/MI
27.7 GDB/MI Command Description Format
======================================
The remaining sections describe blocks of commands. Each block of
commands is laid out in a fashion similar to this section.
Motivation
----------
The motivation for this collection of commands.
Introduction
------------
A brief introduction to this collection of commands as a whole.
Commands
--------
For each command in the block, the following is described:
Synopsis
........
-command ARGS...
Result
......
GDB Command
...........
The corresponding GDB CLI command(s), if any.
Example
.......
Example(s) formatted for readability. Some of the described commands
have not been implemented yet and these are labeled N.A. (not
available).

File: gdb.info, Node: GDB/MI Breakpoint Commands, Next: GDB/MI Program Context, Prev: GDB/MI Command Description Format, Up: GDB/MI
27.8 GDB/MI Breakpoint Commands
===============================
This section documents GDB/MI commands for manipulating breakpoints.
The `-break-after' Command
--------------------------
Synopsis
........
-break-after NUMBER COUNT
The breakpoint number NUMBER is not in effect until it has been hit
COUNT times. To see how this is reflected in the output of the
`-break-list' command, see the description of the `-break-list' command
below.
GDB Command
...........
The corresponding GDB command is `ignore'.
Example
.......
(gdb)
-break-insert main
^done,bkpt={number="1",type="breakpoint",disp="keep",
enabled="y",addr="0x000100d0",func="main",file="hello.c",
fullname="/home/foo/hello.c",line="5",times="0"}
(gdb)
-break-after 1 3
~
^done
(gdb)
-break-list
^done,BreakpointTable={nr_rows="1",nr_cols="6",
hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
{width="14",alignment="-1",col_name="type",colhdr="Type"},
{width="4",alignment="-1",col_name="disp",colhdr="Disp"},
{width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
{width="10",alignment="-1",col_name="addr",colhdr="Address"},
{width="40",alignment="2",col_name="what",colhdr="What"}],
body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y",
addr="0x000100d0",func="main",file="hello.c",fullname="/home/foo/hello.c",
line="5",times="0",ignore="3"}]}
(gdb)
The `-break-commands' Command
-----------------------------
Synopsis
........
-break-commands NUMBER [ COMMAND1 ... COMMANDN ]
Specifies the CLI commands that should be executed when breakpoint
NUMBER is hit. The parameters COMMAND1 to COMMANDN are the commands.
If no command is specified, any previously-set commands are cleared.
*Note Break Commands::. Typical use of this functionality is tracing a
program, that is, printing of values of some variables whenever
breakpoint is hit and then continuing.
GDB Command
...........
The corresponding GDB command is `commands'.
Example
.......
(gdb)
-break-insert main
^done,bkpt={number="1",type="breakpoint",disp="keep",
enabled="y",addr="0x000100d0",func="main",file="hello.c",
fullname="/home/foo/hello.c",line="5",times="0"}
(gdb)
-break-commands 1 "print v" "continue"
^done
(gdb)
The `-break-condition' Command
------------------------------
Synopsis
........
-break-condition NUMBER EXPR
Breakpoint NUMBER will stop the program only if the condition in
EXPR is true. The condition becomes part of the `-break-list' output
(see the description of the `-break-list' command below).
GDB Command
...........
The corresponding GDB command is `condition'.
Example
.......
(gdb)
-break-condition 1 1
^done
(gdb)
-break-list
^done,BreakpointTable={nr_rows="1",nr_cols="6",
hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
{width="14",alignment="-1",col_name="type",colhdr="Type"},
{width="4",alignment="-1",col_name="disp",colhdr="Disp"},
{width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
{width="10",alignment="-1",col_name="addr",colhdr="Address"},
{width="40",alignment="2",col_name="what",colhdr="What"}],
body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y",
addr="0x000100d0",func="main",file="hello.c",fullname="/home/foo/hello.c",
line="5",cond="1",times="0",ignore="3"}]}
(gdb)
The `-break-delete' Command
---------------------------
Synopsis
........
-break-delete ( BREAKPOINT )+
Delete the breakpoint(s) whose number(s) are specified in the
argument list. This is obviously reflected in the breakpoint list.
GDB Command
...........
The corresponding GDB command is `delete'.
Example
.......
(gdb)
-break-delete 1
^done
(gdb)
-break-list
^done,BreakpointTable={nr_rows="0",nr_cols="6",
hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
{width="14",alignment="-1",col_name="type",colhdr="Type"},
{width="4",alignment="-1",col_name="disp",colhdr="Disp"},
{width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
{width="10",alignment="-1",col_name="addr",colhdr="Address"},
{width="40",alignment="2",col_name="what",colhdr="What"}],
body=[]}
(gdb)
The `-break-disable' Command
----------------------------
Synopsis
........
-break-disable ( BREAKPOINT )+
Disable the named BREAKPOINT(s). The field `enabled' in the break
list is now set to `n' for the named BREAKPOINT(s).
GDB Command
...........
The corresponding GDB command is `disable'.
Example
.......
(gdb)
-break-disable 2
^done
(gdb)
-break-list
^done,BreakpointTable={nr_rows="1",nr_cols="6",
hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
{width="14",alignment="-1",col_name="type",colhdr="Type"},
{width="4",alignment="-1",col_name="disp",colhdr="Disp"},
{width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
{width="10",alignment="-1",col_name="addr",colhdr="Address"},
{width="40",alignment="2",col_name="what",colhdr="What"}],
body=[bkpt={number="2",type="breakpoint",disp="keep",enabled="n",
addr="0x000100d0",func="main",file="hello.c",fullname="/home/foo/hello.c",
line="5",times="0"}]}
(gdb)
The `-break-enable' Command
---------------------------
Synopsis
........
-break-enable ( BREAKPOINT )+
Enable (previously disabled) BREAKPOINT(s).
GDB Command
...........
The corresponding GDB command is `enable'.
Example
.......
(gdb)
-break-enable 2
^done
(gdb)
-break-list
^done,BreakpointTable={nr_rows="1",nr_cols="6",
hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
{width="14",alignment="-1",col_name="type",colhdr="Type"},
{width="4",alignment="-1",col_name="disp",colhdr="Disp"},
{width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
{width="10",alignment="-1",col_name="addr",colhdr="Address"},
{width="40",alignment="2",col_name="what",colhdr="What"}],
body=[bkpt={number="2",type="breakpoint",disp="keep",enabled="y",
addr="0x000100d0",func="main",file="hello.c",fullname="/home/foo/hello.c",
line="5",times="0"}]}
(gdb)
The `-break-info' Command
-------------------------
Synopsis
........
-break-info BREAKPOINT
Get information about a single breakpoint.
GDB Command
...........
The corresponding GDB command is `info break BREAKPOINT'.
Example
.......
N.A.
The `-break-insert' Command
---------------------------
Synopsis
........
-break-insert [ -t ] [ -h ] [ -f ] [ -d ] [ -a ]
[ -c CONDITION ] [ -i IGNORE-COUNT ]
[ -p THREAD-ID ] [ LOCATION ]
If specified, LOCATION, can be one of:
* function
* filename:linenum
* filename:function
* *address
The possible optional parameters of this command are:
`-t'
Insert a temporary breakpoint.
`-h'
Insert a hardware breakpoint.
`-f'
If LOCATION cannot be parsed (for example if it refers to unknown
files or functions), create a pending breakpoint. Without this
flag, GDB will report an error, and won't create a breakpoint, if
LOCATION cannot be parsed.
`-d'
Create a disabled breakpoint.
`-a'
Create a tracepoint. *Note Tracepoints::. When this parameter is
used together with `-h', a fast tracepoint is created.
`-c CONDITION'
Make the breakpoint conditional on CONDITION.
`-i IGNORE-COUNT'
Initialize the IGNORE-COUNT.
`-p THREAD-ID'
Restrict the breakpoint to the specified THREAD-ID.
Result
......
The result is in the form:
^done,bkpt={number="NUMBER",type="TYPE",disp="del"|"keep",
enabled="y"|"n",addr="HEX",func="FUNCNAME",file="FILENAME",
fullname="FULL_FILENAME",line="LINENO",[thread="THREADNO,]
times="TIMES"}
where NUMBER is the GDB number for this breakpoint, FUNCNAME is the
name of the function where the breakpoint was inserted, FILENAME is the
name of the source file which contains this function, LINENO is the
source line number within that file and TIMES the number of times that
the breakpoint has been hit (always 0 for -break-insert but may be
greater for -break-info or -break-list which use the same output).
Note: this format is open to change.
GDB Command
...........
The corresponding GDB commands are `break', `tbreak', `hbreak', and
`thbreak'.
Example
.......
(gdb)
-break-insert main
^done,bkpt={number="1",addr="0x0001072c",file="recursive2.c",
fullname="/home/foo/recursive2.c,line="4",times="0"}
(gdb)
-break-insert -t foo
^done,bkpt={number="2",addr="0x00010774",file="recursive2.c",
fullname="/home/foo/recursive2.c,line="11",times="0"}
(gdb)
-break-list
^done,BreakpointTable={nr_rows="2",nr_cols="6",
hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
{width="14",alignment="-1",col_name="type",colhdr="Type"},
{width="4",alignment="-1",col_name="disp",colhdr="Disp"},
{width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
{width="10",alignment="-1",col_name="addr",colhdr="Address"},
{width="40",alignment="2",col_name="what",colhdr="What"}],
body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y",
addr="0x0001072c", func="main",file="recursive2.c",
fullname="/home/foo/recursive2.c,"line="4",times="0"},
bkpt={number="2",type="breakpoint",disp="del",enabled="y",
addr="0x00010774",func="foo",file="recursive2.c",
fullname="/home/foo/recursive2.c",line="11",times="0"}]}
(gdb)
The `-break-list' Command
-------------------------
Synopsis
........
-break-list
Displays the list of inserted breakpoints, showing the following
fields:
`Number'
number of the breakpoint
`Type'
type of the breakpoint: `breakpoint' or `watchpoint'
`Disposition'
should the breakpoint be deleted or disabled when it is hit: `keep'
or `nokeep'
`Enabled'
is the breakpoint enabled or no: `y' or `n'
`Address'
memory location at which the breakpoint is set
`What'
logical location of the breakpoint, expressed by function name,
file name, line number
`Times'
number of times the breakpoint has been hit
If there are no breakpoints or watchpoints, the `BreakpointTable'
`body' field is an empty list.
GDB Command
...........
The corresponding GDB command is `info break'.
Example
.......
(gdb)
-break-list
^done,BreakpointTable={nr_rows="2",nr_cols="6",
hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
{width="14",alignment="-1",col_name="type",colhdr="Type"},
{width="4",alignment="-1",col_name="disp",colhdr="Disp"},
{width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
{width="10",alignment="-1",col_name="addr",colhdr="Address"},
{width="40",alignment="2",col_name="what",colhdr="What"}],
body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y",
addr="0x000100d0",func="main",file="hello.c",line="5",times="0"},
bkpt={number="2",type="breakpoint",disp="keep",enabled="y",
addr="0x00010114",func="foo",file="hello.c",fullname="/home/foo/hello.c",
line="13",times="0"}]}
(gdb)
Here's an example of the result when there are no breakpoints:
(gdb)
-break-list
^done,BreakpointTable={nr_rows="0",nr_cols="6",
hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
{width="14",alignment="-1",col_name="type",colhdr="Type"},
{width="4",alignment="-1",col_name="disp",colhdr="Disp"},
{width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
{width="10",alignment="-1",col_name="addr",colhdr="Address"},
{width="40",alignment="2",col_name="what",colhdr="What"}],
body=[]}
(gdb)
The `-break-passcount' Command
------------------------------
Synopsis
........
-break-passcount TRACEPOINT-NUMBER PASSCOUNT
Set the passcount for tracepoint TRACEPOINT-NUMBER to PASSCOUNT. If
the breakpoint referred to by TRACEPOINT-NUMBER is not a tracepoint,
error is emitted. This corresponds to CLI command `passcount'.
The `-break-watch' Command
--------------------------
Synopsis
........
-break-watch [ -a | -r ]
Create a watchpoint. With the `-a' option it will create an
"access" watchpoint, i.e., a watchpoint that triggers either on a read
from or on a write to the memory location. With the `-r' option, the
watchpoint created is a "read" watchpoint, i.e., it will trigger only
when the memory location is accessed for reading. Without either of
the options, the watchpoint created is a regular watchpoint, i.e., it
will trigger when the memory location is accessed for writing. *Note
Setting Watchpoints: Set Watchpoints.
Note that `-break-list' will report a single list of watchpoints and
breakpoints inserted.
GDB Command
...........
The corresponding GDB commands are `watch', `awatch', and `rwatch'.
Example
.......
Setting a watchpoint on a variable in the `main' function:
(gdb)
-break-watch x
^done,wpt={number="2",exp="x"}
(gdb)
-exec-continue
^running
(gdb)
*stopped,reason="watchpoint-trigger",wpt={number="2",exp="x"},
value={old="-268439212",new="55"},
frame={func="main",args=[],file="recursive2.c",
fullname="/home/foo/bar/recursive2.c",line="5"}
(gdb)
Setting a watchpoint on a variable local to a function. GDB will
stop the program execution twice: first for the variable changing
value, then for the watchpoint going out of scope.
(gdb)
-break-watch C
^done,wpt={number="5",exp="C"}
(gdb)
-exec-continue
^running
(gdb)
*stopped,reason="watchpoint-trigger",
wpt={number="5",exp="C"},value={old="-276895068",new="3"},
frame={func="callee4",args=[],
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="13"}
(gdb)
-exec-continue
^running
(gdb)
*stopped,reason="watchpoint-scope",wpnum="5",
frame={func="callee3",args=[{name="strarg",
value="0x11940 \"A string argument.\""}],
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="18"}
(gdb)
Listing breakpoints and watchpoints, at different points in the
program execution. Note that once the watchpoint goes out of scope, it
is deleted.
(gdb)
-break-watch C
^done,wpt={number="2",exp="C"}
(gdb)
-break-list
^done,BreakpointTable={nr_rows="2",nr_cols="6",
hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
{width="14",alignment="-1",col_name="type",colhdr="Type"},
{width="4",alignment="-1",col_name="disp",colhdr="Disp"},
{width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
{width="10",alignment="-1",col_name="addr",colhdr="Address"},
{width="40",alignment="2",col_name="what",colhdr="What"}],
body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y",
addr="0x00010734",func="callee4",
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
fullname="/home/foo/devo/gdb/testsuite/gdb.mi/basics.c"line="8",times="1"},
bkpt={number="2",type="watchpoint",disp="keep",
enabled="y",addr="",what="C",times="0"}]}
(gdb)
-exec-continue
^running
(gdb)
*stopped,reason="watchpoint-trigger",wpt={number="2",exp="C"},
value={old="-276895068",new="3"},
frame={func="callee4",args=[],
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="13"}
(gdb)
-break-list
^done,BreakpointTable={nr_rows="2",nr_cols="6",
hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
{width="14",alignment="-1",col_name="type",colhdr="Type"},
{width="4",alignment="-1",col_name="disp",colhdr="Disp"},
{width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
{width="10",alignment="-1",col_name="addr",colhdr="Address"},
{width="40",alignment="2",col_name="what",colhdr="What"}],
body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y",
addr="0x00010734",func="callee4",
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
fullname="/home/foo/devo/gdb/testsuite/gdb.mi/basics.c",line="8",times="1"},
bkpt={number="2",type="watchpoint",disp="keep",
enabled="y",addr="",what="C",times="-5"}]}
(gdb)
-exec-continue
^running
^done,reason="watchpoint-scope",wpnum="2",
frame={func="callee3",args=[{name="strarg",
value="0x11940 \"A string argument.\""}],
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="18"}
(gdb)
-break-list
^done,BreakpointTable={nr_rows="1",nr_cols="6",
hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
{width="14",alignment="-1",col_name="type",colhdr="Type"},
{width="4",alignment="-1",col_name="disp",colhdr="Disp"},
{width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
{width="10",alignment="-1",col_name="addr",colhdr="Address"},
{width="40",alignment="2",col_name="what",colhdr="What"}],
body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y",
addr="0x00010734",func="callee4",
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
fullname="/home/foo/devo/gdb/testsuite/gdb.mi/basics.c",line="8",
times="1"}]}
(gdb)

File: gdb.info, Node: GDB/MI Program Context, Next: GDB/MI Thread Commands, Prev: GDB/MI Breakpoint Commands, Up: GDB/MI
27.9 GDB/MI Program Context
============================
The `-exec-arguments' Command
-----------------------------
Synopsis
........
-exec-arguments ARGS
Set the inferior program arguments, to be used in the next
`-exec-run'.
GDB Command
...........
The corresponding GDB command is `set args'.
Example
.......
(gdb)
-exec-arguments -v word
^done
(gdb)
The `-environment-cd' Command
-----------------------------
Synopsis
........
-environment-cd PATHDIR
Set GDB's working directory.
GDB Command
...........
The corresponding GDB command is `cd'.
Example
.......
(gdb)
-environment-cd /kwikemart/marge/ezannoni/flathead-dev/devo/gdb
^done
(gdb)
The `-environment-directory' Command
------------------------------------
Synopsis
........
-environment-directory [ -r ] [ PATHDIR ]+
Add directories PATHDIR to beginning of search path for source files.
If the `-r' option is used, the search path is reset to the default
search path. If directories PATHDIR are supplied in addition to the
`-r' option, the search path is first reset and then addition occurs as
normal. Multiple directories may be specified, separated by blanks.
Specifying multiple directories in a single command results in the
directories added to the beginning of the search path in the same order
they were presented in the command. If blanks are needed as part of a
directory name, double-quotes should be used around the name. In the
command output, the path will show up separated by the system
directory-separator character. The directory-separator character must
not be used in any directory name. If no directories are specified,
the current search path is displayed.
GDB Command
...........
The corresponding GDB command is `dir'.
Example
.......
(gdb)
-environment-directory /kwikemart/marge/ezannoni/flathead-dev/devo/gdb
^done,source-path="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb:$cdir:$cwd"
(gdb)
-environment-directory ""
^done,source-path="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb:$cdir:$cwd"
(gdb)
-environment-directory -r /home/jjohnstn/src/gdb /usr/src
^done,source-path="/home/jjohnstn/src/gdb:/usr/src:$cdir:$cwd"
(gdb)
-environment-directory -r
^done,source-path="$cdir:$cwd"
(gdb)
The `-environment-path' Command
-------------------------------
Synopsis
........
-environment-path [ -r ] [ PATHDIR ]+
Add directories PATHDIR to beginning of search path for object files.
If the `-r' option is used, the search path is reset to the original
search path that existed at gdb start-up. If directories PATHDIR are
supplied in addition to the `-r' option, the search path is first reset
and then addition occurs as normal. Multiple directories may be
specified, separated by blanks. Specifying multiple directories in a
single command results in the directories added to the beginning of the
search path in the same order they were presented in the command. If
blanks are needed as part of a directory name, double-quotes should be
used around the name. In the command output, the path will show up
separated by the system directory-separator character. The
directory-separator character must not be used in any directory name.
If no directories are specified, the current path is displayed.
GDB Command
...........
The corresponding GDB command is `path'.
Example
.......
(gdb)
-environment-path
^done,path="/usr/bin"
(gdb)
-environment-path /kwikemart/marge/ezannoni/flathead-dev/ppc-eabi/gdb /bin
^done,path="/kwikemart/marge/ezannoni/flathead-dev/ppc-eabi/gdb:/bin:/usr/bin"
(gdb)
-environment-path -r /usr/local/bin
^done,path="/usr/local/bin:/usr/bin"
(gdb)
The `-environment-pwd' Command
------------------------------
Synopsis
........
-environment-pwd
Show the current working directory.
GDB Command
...........
The corresponding GDB command is `pwd'.
Example
.......
(gdb)
-environment-pwd
^done,cwd="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb"
(gdb)

File: gdb.info, Node: GDB/MI Thread Commands, Next: GDB/MI Ada Tasking Commands, Prev: GDB/MI Program Context, Up: GDB/MI
27.10 GDB/MI Thread Commands
============================
The `-thread-info' Command
--------------------------
Synopsis
........
-thread-info [ THREAD-ID ]
Reports information about either a specific thread, if the THREAD-ID
parameter is present, or about all threads. When printing information
about all threads, also reports the current thread.
GDB Command
...........
The `info thread' command prints the same information about all threads.
Result
......
The result is a list of threads. The following attributes are defined
for a given thread:
`current'
This field exists only for the current thread. It has the value
`*'.
`id'
The identifier that GDB uses to refer to the thread.
`target-id'
The identifier that the target uses to refer to the thread.
`details'
Extra information about the thread, in a target-specific format.
This field is optional.
`name'
The name of the thread. If the user specified a name using the
`thread name' command, then this name is given. Otherwise, if GDB
can extract the thread name from the target, then that name is
given. If GDB cannot find the thread name, then this field is
omitted.
`frame'
The stack frame currently executing in the thread.
`state'
The thread's state. The `state' field may have the following
values:
`stopped'
The thread is stopped. Frame information is available for
stopped threads.
`running'
The thread is running. There's no frame information for
running threads.
`core'
If GDB can find the CPU core on which this thread is running, then
this field is the core identifier. This field is optional.
Example
.......
-thread-info
^done,threads=[
{id="2",target-id="Thread 0xb7e14b90 (LWP 21257)",
frame={level="0",addr="0xffffe410",func="__kernel_vsyscall",
args=[]},state="running"},
{id="1",target-id="Thread 0xb7e156b0 (LWP 21254)",
frame={level="0",addr="0x0804891f",func="foo",
args=[{name="i",value="10"}],
file="/tmp/a.c",fullname="/tmp/a.c",line="158"},
state="running"}],
current-thread-id="1"
(gdb)
The `-thread-list-ids' Command
------------------------------
Synopsis
........
-thread-list-ids
Produces a list of the currently known GDB thread ids. At the end
of the list it also prints the total number of such threads.
This command is retained for historical reasons, the `-thread-info'
command should be used instead.
GDB Command
...........
Part of `info threads' supplies the same information.
Example
.......
(gdb)
-thread-list-ids
^done,thread-ids={thread-id="3",thread-id="2",thread-id="1"},
current-thread-id="1",number-of-threads="3"
(gdb)
The `-thread-select' Command
----------------------------
Synopsis
........
-thread-select THREADNUM
Make THREADNUM the current thread. It prints the number of the new
current thread, and the topmost frame for that thread.
This command is deprecated in favor of explicitly using the
`--thread' option to each command.
GDB Command
...........
The corresponding GDB command is `thread'.
Example
.......
(gdb)
-exec-next
^running
(gdb)
*stopped,reason="end-stepping-range",thread-id="2",line="187",
file="../../../devo/gdb/testsuite/gdb.threads/linux-dp.c"
(gdb)
-thread-list-ids
^done,
thread-ids={thread-id="3",thread-id="2",thread-id="1"},
number-of-threads="3"
(gdb)
-thread-select 3
^done,new-thread-id="3",
frame={level="0",func="vprintf",
args=[{name="format",value="0x8048e9c \"%*s%c %d %c\\n\""},
{name="arg",value="0x2"}],file="vprintf.c",line="31"}
(gdb)

File: gdb.info, Node: GDB/MI Ada Tasking Commands, Next: GDB/MI Program Execution, Prev: GDB/MI Thread Commands, Up: GDB/MI
27.11 GDB/MI Ada Tasking Commands
=================================
The `-ada-task-info' Command
----------------------------
Synopsis
........
-ada-task-info [ TASK-ID ]
Reports information about either a specific Ada task, if the TASK-ID
parameter is present, or about all Ada tasks.
GDB Command
...........
The `info tasks' command prints the same information about all Ada
tasks (*note Ada Tasks::).
Result
......
The result is a table of Ada tasks. The following columns are defined
for each Ada task:
`current'
This field exists only for the current thread. It has the value
`*'.
`id'
The identifier that GDB uses to refer to the Ada task.
`task-id'
The identifier that the target uses to refer to the Ada task.
`thread-id'
The identifier of the thread corresponding to the Ada task.
This field should always exist, as Ada tasks are always implemented
on top of a thread. But if GDB cannot find this corresponding
thread for any reason, the field is omitted.
`parent-id'
This field exists only when the task was created by another task.
In this case, it provides the ID of the parent task.
`priority'
The base priority of the task.
`state'
The current state of the task. For a detailed description of the
possible states, see *Note Ada Tasks::.
`name'
The name of the task.
Example
.......
-ada-task-info
^done,tasks={nr_rows="3",nr_cols="8",
hdr=[{width="1",alignment="-1",col_name="current",colhdr=""},
{width="3",alignment="1",col_name="id",colhdr="ID"},
{width="9",alignment="1",col_name="task-id",colhdr="TID"},
{width="4",alignment="1",col_name="thread-id",colhdr=""},
{width="4",alignment="1",col_name="parent-id",colhdr="P-ID"},
{width="3",alignment="1",col_name="priority",colhdr="Pri"},
{width="22",alignment="-1",col_name="state",colhdr="State"},
{width="1",alignment="2",col_name="name",colhdr="Name"}],
body=[{current="*",id="1",task-id=" 644010",thread-id="1",priority="48",
state="Child Termination Wait",name="main_task"}]}
(gdb)

File: gdb.info, Node: GDB/MI Program Execution, Next: GDB/MI Stack Manipulation, Prev: GDB/MI Ada Tasking Commands, Up: GDB/MI
27.12 GDB/MI Program Execution
==============================
These are the asynchronous commands which generate the out-of-band
record `*stopped'. Currently GDB only really executes asynchronously
with remote targets and this interaction is mimicked in other cases.
The `-exec-continue' Command
----------------------------
Synopsis
........
-exec-continue [--reverse] [--all|--thread-group N]
Resumes the execution of the inferior program, which will continue
to execute until it reaches a debugger stop event. If the `--reverse'
option is specified, execution resumes in reverse until it reaches a
stop event. Stop events may include
* breakpoints or watchpoints
* signals or exceptions
* the end of the process (or its beginning under `--reverse')
* the end or beginning of a replay log if one is being used.
In all-stop mode (*note All-Stop Mode::), may resume only one
thread, or all threads, depending on the value of the
`scheduler-locking' variable. If `--all' is specified, all threads (in
all inferiors) will be resumed. The `--all' option is ignored in
all-stop mode. If the `--thread-group' options is specified, then all
threads in that thread group are resumed.
GDB Command
...........
The corresponding GDB corresponding is `continue'.
Example
.......
-exec-continue
^running
(gdb)
@Hello world
*stopped,reason="breakpoint-hit",disp="keep",bkptno="2",frame={
func="foo",args=[],file="hello.c",fullname="/home/foo/bar/hello.c",
line="13"}
(gdb)
The `-exec-finish' Command
--------------------------
Synopsis
........
-exec-finish [--reverse]
Resumes the execution of the inferior program until the current
function is exited. Displays the results returned by the function. If
the `--reverse' option is specified, resumes the reverse execution of
the inferior program until the point where current function was called.
GDB Command
...........
The corresponding GDB command is `finish'.
Example
.......
Function returning `void'.
-exec-finish
^running
(gdb)
@hello from foo
*stopped,reason="function-finished",frame={func="main",args=[],
file="hello.c",fullname="/home/foo/bar/hello.c",line="7"}
(gdb)
Function returning other than `void'. The name of the internal GDB
variable storing the result is printed, together with the value itself.
-exec-finish
^running
(gdb)
*stopped,reason="function-finished",frame={addr="0x000107b0",func="foo",
args=[{name="a",value="1"],{name="b",value="9"}},
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"},
gdb-result-var="$1",return-value="0"
(gdb)
The `-exec-interrupt' Command
-----------------------------
Synopsis
........
-exec-interrupt [--all|--thread-group N]
Interrupts the background execution of the target. Note how the
token associated with the stop message is the one for the execution
command that has been interrupted. The token for the interrupt itself
only appears in the `^done' output. If the user is trying to interrupt
a non-running program, an error message will be printed.
Note that when asynchronous execution is enabled, this command is
asynchronous just like other execution commands. That is, first the
`^done' response will be printed, and the target stop will be reported
after that using the `*stopped' notification.
In non-stop mode, only the context thread is interrupted by default.
All threads (in all inferiors) will be interrupted if the `--all'
option is specified. If the `--thread-group' option is specified, all
threads in that group will be interrupted.
GDB Command
...........
The corresponding GDB command is `interrupt'.
Example
.......
(gdb)
111-exec-continue
111^running
(gdb)
222-exec-interrupt
222^done
(gdb)
111*stopped,signal-name="SIGINT",signal-meaning="Interrupt",
frame={addr="0x00010140",func="foo",args=[],file="try.c",
fullname="/home/foo/bar/try.c",line="13"}
(gdb)
(gdb)
-exec-interrupt
^error,msg="mi_cmd_exec_interrupt: Inferior not executing."
(gdb)
The `-exec-jump' Command
------------------------
Synopsis
........
-exec-jump LOCATION
Resumes execution of the inferior program at the location specified
by parameter. *Note Specify Location::, for a description of the
different forms of LOCATION.
GDB Command
...........
The corresponding GDB command is `jump'.
Example
.......
-exec-jump foo.c:10
*running,thread-id="all"
^running
The `-exec-next' Command
------------------------
Synopsis
........
-exec-next [--reverse]
Resumes execution of the inferior program, stopping when the
beginning of the next source line is reached.
If the `--reverse' option is specified, resumes reverse execution of
the inferior program, stopping at the beginning of the previous source
line. If you issue this command on the first line of a function, it
will take you back to the caller of that function, to the source line
where the function was called.
GDB Command
...........
The corresponding GDB command is `next'.
Example
.......
-exec-next
^running
(gdb)
*stopped,reason="end-stepping-range",line="8",file="hello.c"
(gdb)
The `-exec-next-instruction' Command
------------------------------------
Synopsis
........
-exec-next-instruction [--reverse]
Executes one machine instruction. If the instruction is a function
call, continues until the function returns. If the program stops at an
instruction in the middle of a source line, the address will be printed
as well.
If the `--reverse' option is specified, resumes reverse execution of
the inferior program, stopping at the previous instruction. If the
previously executed instruction was a return from another function, it
will continue to execute in reverse until the call to that function
(from the current stack frame) is reached.
GDB Command
...........
The corresponding GDB command is `nexti'.
Example
.......
(gdb)
-exec-next-instruction
^running
(gdb)
*stopped,reason="end-stepping-range",
addr="0x000100d4",line="5",file="hello.c"
(gdb)
The `-exec-return' Command
--------------------------
Synopsis
........
-exec-return
Makes current function return immediately. Doesn't execute the
inferior. Displays the new current frame.
GDB Command
...........
The corresponding GDB command is `return'.
Example
.......
(gdb)
200-break-insert callee4
200^done,bkpt={number="1",addr="0x00010734",
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",line="8"}
(gdb)
000-exec-run
000^running
(gdb)
000*stopped,reason="breakpoint-hit",disp="keep",bkptno="1",
frame={func="callee4",args=[],
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="8"}
(gdb)
205-break-delete
205^done
(gdb)
111-exec-return
111^done,frame={level="0",func="callee3",
args=[{name="strarg",
value="0x11940 \"A string argument.\""}],
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="18"}
(gdb)
The `-exec-run' Command
-----------------------
Synopsis
........
-exec-run [--all | --thread-group N]
Starts execution of the inferior from the beginning. The inferior
executes until either a breakpoint is encountered or the program exits.
In the latter case the output will include an exit code, if the
program has exited exceptionally.
When no option is specified, the current inferior is started. If the
`--thread-group' option is specified, it should refer to a thread group
of type `process', and that thread group will be started. If the
`--all' option is specified, then all inferiors will be started.
GDB Command
...........
The corresponding GDB command is `run'.
Examples
........
(gdb)
-break-insert main
^done,bkpt={number="1",addr="0x0001072c",file="recursive2.c",line="4"}
(gdb)
-exec-run
^running
(gdb)
*stopped,reason="breakpoint-hit",disp="keep",bkptno="1",
frame={func="main",args=[],file="recursive2.c",
fullname="/home/foo/bar/recursive2.c",line="4"}
(gdb)
Program exited normally:
(gdb)
-exec-run
^running
(gdb)
x = 55
*stopped,reason="exited-normally"
(gdb)
Program exited exceptionally:
(gdb)
-exec-run
^running
(gdb)
x = 55
*stopped,reason="exited",exit-code="01"
(gdb)
Another way the program can terminate is if it receives a signal
such as `SIGINT'. In this case, GDB/MI displays this:
(gdb)
*stopped,reason="exited-signalled",signal-name="SIGINT",
signal-meaning="Interrupt"
The `-exec-step' Command
------------------------
Synopsis
........
-exec-step [--reverse]
Resumes execution of the inferior program, stopping when the
beginning of the next source line is reached, if the next source line
is not a function call. If it is, stop at the first instruction of the
called function. If the `--reverse' option is specified, resumes
reverse execution of the inferior program, stopping at the beginning of
the previously executed source line.
GDB Command
...........
The corresponding GDB command is `step'.
Example
.......
Stepping into a function:
-exec-step
^running
(gdb)
*stopped,reason="end-stepping-range",
frame={func="foo",args=[{name="a",value="10"},
{name="b",value="0"}],file="recursive2.c",
fullname="/home/foo/bar/recursive2.c",line="11"}
(gdb)
Regular stepping:
-exec-step
^running
(gdb)
*stopped,reason="end-stepping-range",line="14",file="recursive2.c"
(gdb)
The `-exec-step-instruction' Command
------------------------------------
Synopsis
........
-exec-step-instruction [--reverse]
Resumes the inferior which executes one machine instruction. If the
`--reverse' option is specified, resumes reverse execution of the
inferior program, stopping at the previously executed instruction. The
output, once GDB has stopped, will vary depending on whether we have
stopped in the middle of a source line or not. In the former case, the
address at which the program stopped will be printed as well.
GDB Command
...........
The corresponding GDB command is `stepi'.
Example
.......
(gdb)
-exec-step-instruction
^running
(gdb)
*stopped,reason="end-stepping-range",
frame={func="foo",args=[],file="try.c",
fullname="/home/foo/bar/try.c",line="10"}
(gdb)
-exec-step-instruction
^running
(gdb)
*stopped,reason="end-stepping-range",
frame={addr="0x000100f4",func="foo",args=[],file="try.c",
fullname="/home/foo/bar/try.c",line="10"}
(gdb)
The `-exec-until' Command
-------------------------
Synopsis
........
-exec-until [ LOCATION ]
Executes the inferior until the LOCATION specified in the argument
is reached. If there is no argument, the inferior executes until a
source line greater than the current one is reached. The reason for
stopping in this case will be `location-reached'.
GDB Command
...........
The corresponding GDB command is `until'.
Example
.......
(gdb)
-exec-until recursive2.c:6
^running
(gdb)
x = 55
*stopped,reason="location-reached",frame={func="main",args=[],
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="6"}
(gdb)

File: gdb.info, Node: GDB/MI Stack Manipulation, Next: GDB/MI Variable Objects, Prev: GDB/MI Program Execution, Up: GDB/MI
27.13 GDB/MI Stack Manipulation Commands
========================================
The `-stack-info-frame' Command
-------------------------------
Synopsis
........
-stack-info-frame
Get info on the selected frame.
GDB Command
...........
The corresponding GDB command is `info frame' or `frame' (without
arguments).
Example
.......
(gdb)
-stack-info-frame
^done,frame={level="1",addr="0x0001076c",func="callee3",
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="17"}
(gdb)
The `-stack-info-depth' Command
-------------------------------
Synopsis
........
-stack-info-depth [ MAX-DEPTH ]
Return the depth of the stack. If the integer argument MAX-DEPTH is
specified, do not count beyond MAX-DEPTH frames.
GDB Command
...........
There's no equivalent GDB command.
Example
.......
For a stack with frame levels 0 through 11:
(gdb)
-stack-info-depth
^done,depth="12"
(gdb)
-stack-info-depth 4
^done,depth="4"
(gdb)
-stack-info-depth 12
^done,depth="12"
(gdb)
-stack-info-depth 11
^done,depth="11"
(gdb)
-stack-info-depth 13
^done,depth="12"
(gdb)
The `-stack-list-arguments' Command
-----------------------------------
Synopsis
........
-stack-list-arguments PRINT-VALUES
[ LOW-FRAME HIGH-FRAME ]
Display a list of the arguments for the frames between LOW-FRAME and
HIGH-FRAME (inclusive). If LOW-FRAME and HIGH-FRAME are not provided,
list the arguments for the whole call stack. If the two arguments are
equal, show the single frame at the corresponding level. It is an
error if LOW-FRAME is larger than the actual number of frames. On the
other hand, HIGH-FRAME may be larger than the actual number of frames,
in which case only existing frames will be returned.
If PRINT-VALUES is 0 or `--no-values', print only the names of the
variables; if it is 1 or `--all-values', print also their values; and
if it is 2 or `--simple-values', print the name, type and value for
simple data types, and the name and type for arrays, structures and
unions.
Use of this command to obtain arguments in a single frame is
deprecated in favor of the `-stack-list-variables' command.
GDB Command
...........
GDB does not have an equivalent command. `gdbtk' has a `gdb_get_args'
command which partially overlaps with the functionality of
`-stack-list-arguments'.
Example
.......
(gdb)
-stack-list-frames
^done,
stack=[
frame={level="0",addr="0x00010734",func="callee4",
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="8"},
frame={level="1",addr="0x0001076c",func="callee3",
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="17"},
frame={level="2",addr="0x0001078c",func="callee2",
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="22"},
frame={level="3",addr="0x000107b4",func="callee1",
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="27"},
frame={level="4",addr="0x000107e0",func="main",
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="32"}]
(gdb)
-stack-list-arguments 0
^done,
stack-args=[
frame={level="0",args=[]},
frame={level="1",args=[name="strarg"]},
frame={level="2",args=[name="intarg",name="strarg"]},
frame={level="3",args=[name="intarg",name="strarg",name="fltarg"]},
frame={level="4",args=[]}]
(gdb)
-stack-list-arguments 1
^done,
stack-args=[
frame={level="0",args=[]},
frame={level="1",
args=[{name="strarg",value="0x11940 \"A string argument.\""}]},
frame={level="2",args=[
{name="intarg",value="2"},
{name="strarg",value="0x11940 \"A string argument.\""}]},
{frame={level="3",args=[
{name="intarg",value="2"},
{name="strarg",value="0x11940 \"A string argument.\""},
{name="fltarg",value="3.5"}]},
frame={level="4",args=[]}]
(gdb)
-stack-list-arguments 0 2 2
^done,stack-args=[frame={level="2",args=[name="intarg",name="strarg"]}]
(gdb)
-stack-list-arguments 1 2 2
^done,stack-args=[frame={level="2",
args=[{name="intarg",value="2"},
{name="strarg",value="0x11940 \"A string argument.\""}]}]
(gdb)
The `-stack-list-frames' Command
--------------------------------
Synopsis
........
-stack-list-frames [ LOW-FRAME HIGH-FRAME ]
List the frames currently on the stack. For each frame it displays
the following info:
`LEVEL'
The frame number, 0 being the topmost frame, i.e., the innermost
function.
`ADDR'
The `$pc' value for that frame.
`FUNC'
Function name.
`FILE'
File name of the source file where the function lives.
`FULLNAME'
The full file name of the source file where the function lives.
`LINE'
Line number corresponding to the `$pc'.
`FROM'
The shared library where this function is defined. This is only
given if the frame's function is not known.
If invoked without arguments, this command prints a backtrace for the
whole stack. If given two integer arguments, it shows the frames whose
levels are between the two arguments (inclusive). If the two arguments
are equal, it shows the single frame at the corresponding level. It is
an error if LOW-FRAME is larger than the actual number of frames. On
the other hand, HIGH-FRAME may be larger than the actual number of
frames, in which case only existing frames will be returned.
GDB Command
...........
The corresponding GDB commands are `backtrace' and `where'.
Example
.......
Full stack backtrace:
(gdb)
-stack-list-frames
^done,stack=
[frame={level="0",addr="0x0001076c",func="foo",
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="11"},
frame={level="1",addr="0x000107a4",func="foo",
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"},
frame={level="2",addr="0x000107a4",func="foo",
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"},
frame={level="3",addr="0x000107a4",func="foo",
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"},
frame={level="4",addr="0x000107a4",func="foo",
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"},
frame={level="5",addr="0x000107a4",func="foo",
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"},
frame={level="6",addr="0x000107a4",func="foo",
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"},
frame={level="7",addr="0x000107a4",func="foo",
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"},
frame={level="8",addr="0x000107a4",func="foo",
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"},
frame={level="9",addr="0x000107a4",func="foo",
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"},
frame={level="10",addr="0x000107a4",func="foo",
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"},
frame={level="11",addr="0x00010738",func="main",
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="4"}]
(gdb)
Show frames between LOW_FRAME and HIGH_FRAME:
(gdb)
-stack-list-frames 3 5
^done,stack=
[frame={level="3",addr="0x000107a4",func="foo",
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"},
frame={level="4",addr="0x000107a4",func="foo",
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"},
frame={level="5",addr="0x000107a4",func="foo",
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"}]
(gdb)
Show a single frame:
(gdb)
-stack-list-frames 3 3
^done,stack=
[frame={level="3",addr="0x000107a4",func="foo",
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"}]
(gdb)
The `-stack-list-locals' Command
--------------------------------
Synopsis
........
-stack-list-locals PRINT-VALUES
Display the local variable names for the selected frame. If
PRINT-VALUES is 0 or `--no-values', print only the names of the
variables; if it is 1 or `--all-values', print also their values; and
if it is 2 or `--simple-values', print the name, type and value for
simple data types, and the name and type for arrays, structures and
unions. In this last case, a frontend can immediately display the
value of simple data types and create variable objects for other data
types when the user wishes to explore their values in more detail.
This command is deprecated in favor of the `-stack-list-variables'
command.
GDB Command
...........
`info locals' in GDB, `gdb_get_locals' in `gdbtk'.
Example
.......
(gdb)
-stack-list-locals 0
^done,locals=[name="A",name="B",name="C"]
(gdb)
-stack-list-locals --all-values
^done,locals=[{name="A",value="1"},{name="B",value="2"},
{name="C",value="{1, 2, 3}"}]
-stack-list-locals --simple-values
^done,locals=[{name="A",type="int",value="1"},
{name="B",type="int",value="2"},{name="C",type="int [3]"}]
(gdb)
The `-stack-list-variables' Command
-----------------------------------
Synopsis
........
-stack-list-variables PRINT-VALUES
Display the names of local variables and function arguments for the
selected frame. If PRINT-VALUES is 0 or `--no-values', print only the
names of the variables; if it is 1 or `--all-values', print also their
values; and if it is 2 or `--simple-values', print the name, type and
value for simple data types, and the name and type for arrays,
structures and unions.
Example
.......
(gdb)
-stack-list-variables --thread 1 --frame 0 --all-values
^done,variables=[{name="x",value="11"},{name="s",value="{a = 1, b = 2}"}]
(gdb)
The `-stack-select-frame' Command
---------------------------------
Synopsis
........
-stack-select-frame FRAMENUM
Change the selected frame. Select a different frame FRAMENUM on the
stack.
This command in deprecated in favor of passing the `--frame' option
to every command.
GDB Command
...........
The corresponding GDB commands are `frame', `up', `down',
`select-frame', `up-silent', and `down-silent'.
Example
.......
(gdb)
-stack-select-frame 2
^done
(gdb)

File: gdb.info, Node: GDB/MI Variable Objects, Next: GDB/MI Data Manipulation, Prev: GDB/MI Stack Manipulation, Up: GDB/MI
27.14 GDB/MI Variable Objects
=============================
Introduction to Variable Objects
--------------------------------
Variable objects are "object-oriented" MI interface for examining and
changing values of expressions. Unlike some other MI interfaces that
work with expressions, variable objects are specifically designed for
simple and efficient presentation in the frontend. A variable object
is identified by string name. When a variable object is created, the
frontend specifies the expression for that variable object. The
expression can be a simple variable, or it can be an arbitrary complex
expression, and can even involve CPU registers. After creating a
variable object, the frontend can invoke other variable object
operations--for example to obtain or change the value of a variable
object, or to change display format.
Variable objects have hierarchical tree structure. Any variable
object that corresponds to a composite type, such as structure in C, has
a number of child variable objects, for example corresponding to each
element of a structure. A child variable object can itself have
children, recursively. Recursion ends when we reach leaf variable
objects, which always have built-in types. Child variable objects are
created only by explicit request, so if a frontend is not interested in
the children of a particular variable object, no child will be created.
For a leaf variable object it is possible to obtain its value as a
string, or set the value from a string. String value can be also
obtained for a non-leaf variable object, but it's generally a string
that only indicates the type of the object, and does not list its
contents. Assignment to a non-leaf variable object is not allowed.
A frontend does not need to read the values of all variable objects
each time the program stops. Instead, MI provides an update command
that lists all variable objects whose values has changed since the last
update operation. This considerably reduces the amount of data that
must be transferred to the frontend. As noted above, children variable
objects are created on demand, and only leaf variable objects have a
real value. As result, gdb will read target memory only for leaf
variables that frontend has created.
The automatic update is not always desirable. For example, a
frontend might want to keep a value of some expression for future
reference, and never update it. For another example, fetching memory
is relatively slow for embedded targets, so a frontend might want to
disable automatic update for the variables that are either not visible
on the screen, or "closed". This is possible using so called "frozen
variable objects". Such variable objects are never implicitly updated.
Variable objects can be either "fixed" or "floating". For the fixed
variable object, the expression is parsed when the variable object is
created, including associating identifiers to specific variables. The
meaning of expression never changes. For a floating variable object
the values of variables whose names appear in the expressions are
re-evaluated every time in the context of the current frame. Consider
this example:
void do_work(...)
{
struct work_state state;
if (...)
do_work(...);
}
If a fixed variable object for the `state' variable is created in
this function, and we enter the recursive call, the variable object
will report the value of `state' in the top-level `do_work' invocation.
On the other hand, a floating variable object will report the value of
`state' in the current frame.
If an expression specified when creating a fixed variable object
refers to a local variable, the variable object becomes bound to the
thread and frame in which the variable object is created. When such
variable object is updated, GDB makes sure that the thread/frame
combination the variable object is bound to still exists, and
re-evaluates the variable object in context of that thread/frame.
The following is the complete set of GDB/MI operations defined to
access this functionality:
*Operation* *Description*
`-enable-pretty-printing' enable Python-based pretty-printing
`-var-create' create a variable object
`-var-delete' delete the variable object and/or its
children
`-var-set-format' set the display format of this variable
`-var-show-format' show the display format of this variable
`-var-info-num-children' tells how many children this object has
`-var-list-children' return a list of the object's children
`-var-info-type' show the type of this variable object
`-var-info-expression' print parent-relative expression that this
variable object represents
`-var-info-path-expression' print full expression that this variable
object represents
`-var-show-attributes' is this variable editable? does it exist
here?
`-var-evaluate-expression' get the value of this variable
`-var-assign' set the value of this variable
`-var-update' update the variable and its children
`-var-set-frozen' set frozeness attribute
`-var-set-update-range' set range of children to display on update
In the next subsection we describe each operation in detail and
suggest how it can be used.
Description And Use of Operations on Variable Objects
-----------------------------------------------------
The `-enable-pretty-printing' Command
-------------------------------------
-enable-pretty-printing
GDB allows Python-based visualizers to affect the output of the MI
variable object commands. However, because there was no way to
implement this in a fully backward-compatible way, a front end must
request that this functionality be enabled.
Once enabled, this feature cannot be disabled.
Note that if Python support has not been compiled into GDB, this
command will still succeed (and do nothing).
This feature is currently (as of GDB 7.0) experimental, and may work
differently in future versions of GDB.
The `-var-create' Command
-------------------------
Synopsis
........
-var-create {NAME | "-"}
{FRAME-ADDR | "*" | "@"} EXPRESSION
This operation creates a variable object, which allows the
monitoring of a variable, the result of an expression, a memory cell or
a CPU register.
The NAME parameter is the string by which the object can be
referenced. It must be unique. If `-' is specified, the varobj system
will generate a string "varNNNNNN" automatically. It will be unique
provided that one does not specify NAME of that format. The command
fails if a duplicate name is found.
The frame under which the expression should be evaluated can be
specified by FRAME-ADDR. A `*' indicates that the current frame should
be used. A `@' indicates that a floating variable object must be
created.
EXPRESSION is any expression valid on the current language set (must
not begin with a `*'), or one of the following:
* `*ADDR', where ADDR is the address of a memory cell
* `*ADDR-ADDR' -- a memory address range (TBD)
* `$REGNAME' -- a CPU register name
A varobj's contents may be provided by a Python-based
pretty-printer. In this case the varobj is known as a "dynamic
varobj". Dynamic varobjs have slightly different semantics in some
cases. If the `-enable-pretty-printing' command is not sent, then GDB
will never create a dynamic varobj. This ensures backward
compatibility for existing clients.
Result
......
This operation returns attributes of the newly-created varobj. These
are:
`name'
The name of the varobj.
`numchild'
The number of children of the varobj. This number is not
necessarily reliable for a dynamic varobj. Instead, you must
examine the `has_more' attribute.
`value'
The varobj's scalar value. For a varobj whose type is some sort of
aggregate (e.g., a `struct'), or for a dynamic varobj, this value
will not be interesting.
`type'
The varobj's type. This is a string representation of the type, as
would be printed by the GDB CLI. If `print object' (*note set
print object: Print Settings.) is set to `on', the _actual_
(derived) type of the object is shown rather than the _declared_
one.
`thread-id'
If a variable object is bound to a specific thread, then this is
the thread's identifier.
`has_more'
For a dynamic varobj, this indicates whether there appear to be any
children available. For a non-dynamic varobj, this will be 0.
`dynamic'
This attribute will be present and have the value `1' if the
varobj is a dynamic varobj. If the varobj is not a dynamic varobj,
then this attribute will not be present.
`displayhint'
A dynamic varobj can supply a display hint to the front end. The
value comes directly from the Python pretty-printer object's
`display_hint' method. *Note Pretty Printing API::.
Typical output will look like this:
name="NAME",numchild="N",type="TYPE",thread-id="M",
has_more="HAS_MORE"
The `-var-delete' Command
-------------------------
Synopsis
........
-var-delete [ -c ] NAME
Deletes a previously created variable object and all of its children.
With the `-c' option, just deletes the children.
Returns an error if the object NAME is not found.
The `-var-set-format' Command
-----------------------------
Synopsis
........
-var-set-format NAME FORMAT-SPEC
Sets the output format for the value of the object NAME to be
FORMAT-SPEC.
The syntax for the FORMAT-SPEC is as follows:
FORMAT-SPEC ==>
{binary | decimal | hexadecimal | octal | natural}
The natural format is the default format choosen automatically based
on the variable type (like decimal for an `int', hex for pointers,
etc.).
For a variable with children, the format is set only on the variable
itself, and the children are not affected.
The `-var-show-format' Command
------------------------------
Synopsis
........
-var-show-format NAME
Returns the format used to display the value of the object NAME.
FORMAT ==>
FORMAT-SPEC
The `-var-info-num-children' Command
------------------------------------
Synopsis
........
-var-info-num-children NAME
Returns the number of children of a variable object NAME:
numchild=N
Note that this number is not completely reliable for a dynamic
varobj. It will return the current number of children, but more
children may be available.
The `-var-list-children' Command
--------------------------------
Synopsis
........
-var-list-children [PRINT-VALUES] NAME [FROM TO]
Return a list of the children of the specified variable object and
create variable objects for them, if they do not already exist. With a
single argument or if PRINT-VALUES has a value of 0 or `--no-values',
print only the names of the variables; if PRINT-VALUES is 1 or
`--all-values', also print their values; and if it is 2 or
`--simple-values' print the name and value for simple data types and
just the name for arrays, structures and unions.
FROM and TO, if specified, indicate the range of children to report.
If FROM or TO is less than zero, the range is reset and all children
will be reported. Otherwise, children starting at FROM (zero-based)
and up to and excluding TO will be reported.
If a child range is requested, it will only affect the current call
to `-var-list-children', but not future calls to `-var-update'. For
this, you must instead use `-var-set-update-range'. The intent of this
approach is to enable a front end to implement any update approach it
likes; for example, scrolling a view may cause the front end to request
more children with `-var-list-children', and then the front end could
call `-var-set-update-range' with a different range to ensure that
future updates are restricted to just the visible items.
For each child the following results are returned:
NAME
Name of the variable object created for this child.
EXP
The expression to be shown to the user by the front end to
designate this child. For example this may be the name of a
structure member.
For a dynamic varobj, this value cannot be used to form an
expression. There is no way to do this at all with a dynamic
varobj.
For C/C++ structures there are several pseudo children returned to
designate access qualifiers. For these pseudo children EXP is
`public', `private', or `protected'. In this case the type and
value are not present.
A dynamic varobj will not report the access qualifying
pseudo-children, regardless of the language. This information is
not available at all with a dynamic varobj.
NUMCHILD
Number of children this child has. For a dynamic varobj, this
will be 0.
TYPE
The type of the child. If `print object' (*note set print object:
Print Settings.) is set to `on', the _actual_ (derived) type of
the object is shown rather than the _declared_ one.
VALUE
If values were requested, this is the value.
THREAD-ID
If this variable object is associated with a thread, this is the
thread id. Otherwise this result is not present.
FROZEN
If the variable object is frozen, this variable will be present
with a value of 1.
The result may have its own attributes:
`displayhint'
A dynamic varobj can supply a display hint to the front end. The
value comes directly from the Python pretty-printer object's
`display_hint' method. *Note Pretty Printing API::.
`has_more'
This is an integer attribute which is nonzero if there are children
remaining after the end of the selected range.
Example
.......
(gdb)
-var-list-children n
^done,numchild=N,children=[child={name=NAME,exp=EXP,
numchild=N,type=TYPE},(repeats N times)]
(gdb)
-var-list-children --all-values n
^done,numchild=N,children=[child={name=NAME,exp=EXP,
numchild=N,value=VALUE,type=TYPE},(repeats N times)]
The `-var-info-type' Command
----------------------------
Synopsis
........
-var-info-type NAME
Returns the type of the specified variable NAME. The type is
returned as a string in the same format as it is output by the GDB CLI:
type=TYPENAME
The `-var-info-expression' Command
----------------------------------
Synopsis
........
-var-info-expression NAME
Returns a string that is suitable for presenting this variable
object in user interface. The string is generally not valid expression
in the current language, and cannot be evaluated.
For example, if `a' is an array, and variable object `A' was created
for `a', then we'll get this output:
(gdb) -var-info-expression A.1
^done,lang="C",exp="1"
Here, the values of `lang' can be `{"C" | "C++" | "Java"}'.
Note that the output of the `-var-list-children' command also
includes those expressions, so the `-var-info-expression' command is of
limited use.
The `-var-info-path-expression' Command
---------------------------------------
Synopsis
........
-var-info-path-expression NAME
Returns an expression that can be evaluated in the current context
and will yield the same value that a variable object has. Compare this
with the `-var-info-expression' command, which result can be used only
for UI presentation. Typical use of the `-var-info-path-expression'
command is creating a watchpoint from a variable object.
This command is currently not valid for children of a dynamic varobj,
and will give an error when invoked on one.
For example, suppose `C' is a C++ class, derived from class `Base',
and that the `Base' class has a member called `m_size'. Assume a
variable `c' is has the type of `C' and a variable object `C' was
created for variable `c'. Then, we'll get this output:
(gdb) -var-info-path-expression C.Base.public.m_size
^done,path_expr=((Base)c).m_size)
The `-var-show-attributes' Command
----------------------------------
Synopsis
........
-var-show-attributes NAME
List attributes of the specified variable object NAME:
status=ATTR [ ( ,ATTR )* ]
where ATTR is `{ { editable | noneditable } | TBD }'.
The `-var-evaluate-expression' Command
--------------------------------------
Synopsis
........
-var-evaluate-expression [-f FORMAT-SPEC] NAME
Evaluates the expression that is represented by the specified
variable object and returns its value as a string. The format of the
string can be specified with the `-f' option. The possible values of
this option are the same as for `-var-set-format' (*note
-var-set-format::). If the `-f' option is not specified, the current
display format will be used. The current display format can be changed
using the `-var-set-format' command.
value=VALUE
Note that one must invoke `-var-list-children' for a variable before
the value of a child variable can be evaluated.
The `-var-assign' Command
-------------------------
Synopsis
........
-var-assign NAME EXPRESSION
Assigns the value of EXPRESSION to the variable object specified by
NAME. The object must be `editable'. If the variable's value is
altered by the assign, the variable will show up in any subsequent
`-var-update' list.
Example
.......
(gdb)
-var-assign var1 3
^done,value="3"
(gdb)
-var-update *
^done,changelist=[{name="var1",in_scope="true",type_changed="false"}]
(gdb)
The `-var-update' Command
-------------------------
Synopsis
........
-var-update [PRINT-VALUES] {NAME | "*"}
Reevaluate the expressions corresponding to the variable object NAME
and all its direct and indirect children, and return the list of
variable objects whose values have changed; NAME must be a root
variable object. Here, "changed" means that the result of
`-var-evaluate-expression' before and after the `-var-update' is
different. If `*' is used as the variable object names, all existing
variable objects are updated, except for frozen ones (*note
-var-set-frozen::). The option PRINT-VALUES determines whether both
names and values, or just names are printed. The possible values of
this option are the same as for `-var-list-children' (*note
-var-list-children::). It is recommended to use the `--all-values'
option, to reduce the number of MI commands needed on each program stop.
With the `*' parameter, if a variable object is bound to a currently
running thread, it will not be updated, without any diagnostic.
If `-var-set-update-range' was previously used on a varobj, then
only the selected range of children will be reported.
`-var-update' reports all the changed varobjs in a tuple named
`changelist'.
Each item in the change list is itself a tuple holding:
`name'
The name of the varobj.
`value'
If values were requested for this update, then this field will be
present and will hold the value of the varobj.
`in_scope'
This field is a string which may take one of three values:
`"true"'
The variable object's current value is valid.
`"false"'
The variable object does not currently hold a valid value but
it may hold one in the future if its associated expression
comes back into scope.
`"invalid"'
The variable object no longer holds a valid value. This can
occur when the executable file being debugged has changed,
either through recompilation or by using the GDB `file'
command. The front end should normally choose to delete
these variable objects.
In the future new values may be added to this list so the front
should be prepared for this possibility. *Note GDB/MI Development
and Front Ends: GDB/MI Development and Front Ends.
`type_changed'
This is only present if the varobj is still valid. If the type
changed, then this will be the string `true'; otherwise it will be
`false'.
When a varobj's type changes, its children are also likely to have
become incorrect. Therefore, the varobj's children are
automatically deleted when this attribute is `true'. Also, the
varobj's update range, when set using the `-var-set-update-range'
command, is unset.
`new_type'
If the varobj's type changed, then this field will be present and
will hold the new type.
`new_num_children'
For a dynamic varobj, if the number of children changed, or if the
type changed, this will be the new number of children.
The `numchild' field in other varobj responses is generally not
valid for a dynamic varobj - it will show the number of children
that GDB knows about, but because dynamic varobjs lazily
instantiate their children, this will not reflect the number of
children which may be available.
The `new_num_children' attribute only reports changes to the
number of children known by GDB. This is the only way to detect
whether an update has removed children (which necessarily can only
happen at the end of the update range).
`displayhint'
The display hint, if any.
`has_more'
This is an integer value, which will be 1 if there are more
children available outside the varobj's update range.
`dynamic'
This attribute will be present and have the value `1' if the
varobj is a dynamic varobj. If the varobj is not a dynamic varobj,
then this attribute will not be present.
`new_children'
If new children were added to a dynamic varobj within the selected
update range (as set by `-var-set-update-range'), then they will
be listed in this attribute.
Example
.......
(gdb)
-var-assign var1 3
^done,value="3"
(gdb)
-var-update --all-values var1
^done,changelist=[{name="var1",value="3",in_scope="true",
type_changed="false"}]
(gdb)
The `-var-set-frozen' Command
-----------------------------
Synopsis
........
-var-set-frozen NAME FLAG
Set the frozenness flag on the variable object NAME. The FLAG
parameter should be either `1' to make the variable frozen or `0' to
make it unfrozen. If a variable object is frozen, then neither itself,
nor any of its children, are implicitly updated by `-var-update' of a
parent variable or by `-var-update *'. Only `-var-update' of the
variable itself will update its value and values of its children.
After a variable object is unfrozen, it is implicitly updated by all
subsequent `-var-update' operations. Unfreezing a variable does not
update it, only subsequent `-var-update' does.
Example
.......
(gdb)
-var-set-frozen V 1
^done
(gdb)
The `-var-set-update-range' command
-----------------------------------
Synopsis
........
-var-set-update-range NAME FROM TO
Set the range of children to be returned by future invocations of
`-var-update'.
FROM and TO indicate the range of children to report. If FROM or TO
is less than zero, the range is reset and all children will be
reported. Otherwise, children starting at FROM (zero-based) and up to
and excluding TO will be reported.
Example
.......
(gdb)
-var-set-update-range V 1 2
^done
The `-var-set-visualizer' command
---------------------------------
Synopsis
........
-var-set-visualizer NAME VISUALIZER
Set a visualizer for the variable object NAME.
VISUALIZER is the visualizer to use. The special value `None' means
to disable any visualizer in use.
If not `None', VISUALIZER must be a Python expression. This
expression must evaluate to a callable object which accepts a single
argument. GDB will call this object with the value of the varobj NAME
as an argument (this is done so that the same Python pretty-printing
code can be used for both the CLI and MI). When called, this object
must return an object which conforms to the pretty-printing interface
(*note Pretty Printing API::).
The pre-defined function `gdb.default_visualizer' may be used to
select a visualizer by following the built-in process (*note Selecting
Pretty-Printers::). This is done automatically when a varobj is
created, and so ordinarily is not needed.
This feature is only available if Python support is enabled. The MI
command `-list-features' (*note GDB/MI Miscellaneous Commands::) can be
used to check this.
Example
.......
Resetting the visualizer:
(gdb)
-var-set-visualizer V None
^done
Reselecting the default (type-based) visualizer:
(gdb)
-var-set-visualizer V gdb.default_visualizer
^done
Suppose `SomeClass' is a visualizer class. A lambda expression can
be used to instantiate this class for a varobj:
(gdb)
-var-set-visualizer V "lambda val: SomeClass()"
^done

File: gdb.info, Node: GDB/MI Data Manipulation, Next: GDB/MI Tracepoint Commands, Prev: GDB/MI Variable Objects, Up: GDB/MI
27.15 GDB/MI Data Manipulation
==============================
This section describes the GDB/MI commands that manipulate data:
examine memory and registers, evaluate expressions, etc.
The `-data-disassemble' Command
-------------------------------
Synopsis
........
-data-disassemble
[ -s START-ADDR -e END-ADDR ]
| [ -f FILENAME -l LINENUM [ -n LINES ] ]
-- MODE
Where:
`START-ADDR'
is the beginning address (or `$pc')
`END-ADDR'
is the end address
`FILENAME'
is the name of the file to disassemble
`LINENUM'
is the line number to disassemble around
`LINES'
is the number of disassembly lines to be produced. If it is -1,
the whole function will be disassembled, in case no END-ADDR is
specified. If END-ADDR is specified as a non-zero value, and
LINES is lower than the number of disassembly lines between
START-ADDR and END-ADDR, only LINES lines are displayed; if LINES
is higher than the number of lines between START-ADDR and
END-ADDR, only the lines up to END-ADDR are displayed.
`MODE'
is either 0 (meaning only disassembly), 1 (meaning mixed source and
disassembly), 2 (meaning disassembly with raw opcodes), or 3
(meaning mixed source and disassembly with raw opcodes).
Result
......
The output for each instruction is composed of four fields:
* Address
* Func-name
* Offset
* Instruction
Note that whatever included in the instruction field, is not
manipulated directly by GDB/MI, i.e., it is not possible to adjust its
format.
GDB Command
...........
There's no direct mapping from this command to the CLI.
Example
.......
Disassemble from the current value of `$pc' to `$pc + 20':
(gdb)
-data-disassemble -s $pc -e "$pc + 20" -- 0
^done,
asm_insns=[
{address="0x000107c0",func-name="main",offset="4",
inst="mov 2, %o0"},
{address="0x000107c4",func-name="main",offset="8",
inst="sethi %hi(0x11800), %o2"},
{address="0x000107c8",func-name="main",offset="12",
inst="or %o2, 0x140, %o1\t! 0x11940 <_lib_version+8>"},
{address="0x000107cc",func-name="main",offset="16",
inst="sethi %hi(0x11800), %o2"},
{address="0x000107d0",func-name="main",offset="20",
inst="or %o2, 0x168, %o4\t! 0x11968 <_lib_version+48>"}]
(gdb)
Disassemble the whole `main' function. Line 32 is part of `main'.
-data-disassemble -f basics.c -l 32 -- 0
^done,asm_insns=[
{address="0x000107bc",func-name="main",offset="0",
inst="save %sp, -112, %sp"},
{address="0x000107c0",func-name="main",offset="4",
inst="mov 2, %o0"},
{address="0x000107c4",func-name="main",offset="8",
inst="sethi %hi(0x11800), %o2"},
[...]
{address="0x0001081c",func-name="main",offset="96",inst="ret "},
{address="0x00010820",func-name="main",offset="100",inst="restore "}]
(gdb)
Disassemble 3 instructions from the start of `main':
(gdb)
-data-disassemble -f basics.c -l 32 -n 3 -- 0
^done,asm_insns=[
{address="0x000107bc",func-name="main",offset="0",
inst="save %sp, -112, %sp"},
{address="0x000107c0",func-name="main",offset="4",
inst="mov 2, %o0"},
{address="0x000107c4",func-name="main",offset="8",
inst="sethi %hi(0x11800), %o2"}]
(gdb)
Disassemble 3 instructions from the start of `main' in mixed mode:
(gdb)
-data-disassemble -f basics.c -l 32 -n 3 -- 1
^done,asm_insns=[
src_and_asm_line={line="31",
file="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb/ \
testsuite/gdb.mi/basics.c",line_asm_insn=[
{address="0x000107bc",func-name="main",offset="0",
inst="save %sp, -112, %sp"}]},
src_and_asm_line={line="32",
file="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb/ \
testsuite/gdb.mi/basics.c",line_asm_insn=[
{address="0x000107c0",func-name="main",offset="4",
inst="mov 2, %o0"},
{address="0x000107c4",func-name="main",offset="8",
inst="sethi %hi(0x11800), %o2"}]}]
(gdb)
The `-data-evaluate-expression' Command
---------------------------------------
Synopsis
........
-data-evaluate-expression EXPR
Evaluate EXPR as an expression. The expression could contain an
inferior function call. The function call will execute synchronously.
If the expression contains spaces, it must be enclosed in double quotes.
GDB Command
...........
The corresponding GDB commands are `print', `output', and `call'. In
`gdbtk' only, there's a corresponding `gdb_eval' command.
Example
.......
In the following example, the numbers that precede the commands are the
"tokens" described in *Note GDB/MI Command Syntax: GDB/MI Command
Syntax. Notice how GDB/MI returns the same tokens in its output.
211-data-evaluate-expression A
211^done,value="1"
(gdb)
311-data-evaluate-expression &A
311^done,value="0xefffeb7c"
(gdb)
411-data-evaluate-expression A+3
411^done,value="4"
(gdb)
511-data-evaluate-expression "A + 3"
511^done,value="4"
(gdb)
The `-data-list-changed-registers' Command
------------------------------------------
Synopsis
........
-data-list-changed-registers
Display a list of the registers that have changed.
GDB Command
...........
GDB doesn't have a direct analog for this command; `gdbtk' has the
corresponding command `gdb_changed_register_list'.
Example
.......
On a PPC MBX board:
(gdb)
-exec-continue
^running
(gdb)
*stopped,reason="breakpoint-hit",disp="keep",bkptno="1",frame={
func="main",args=[],file="try.c",fullname="/home/foo/bar/try.c",
line="5"}
(gdb)
-data-list-changed-registers
^done,changed-registers=["0","1","2","4","5","6","7","8","9",
"10","11","13","14","15","16","17","18","19","20","21","22","23",
"24","25","26","27","28","30","31","64","65","66","67","69"]
(gdb)
The `-data-list-register-names' Command
---------------------------------------
Synopsis
........
-data-list-register-names [ ( REGNO )+ ]
Show a list of register names for the current target. If no
arguments are given, it shows a list of the names of all the registers.
If integer numbers are given as arguments, it will print a list of the
names of the registers corresponding to the arguments. To ensure
consistency between a register name and its number, the output list may
include empty register names.
GDB Command
...........
GDB does not have a command which corresponds to
`-data-list-register-names'. In `gdbtk' there is a corresponding
command `gdb_regnames'.
Example
.......
For the PPC MBX board:
(gdb)
-data-list-register-names
^done,register-names=["r0","r1","r2","r3","r4","r5","r6","r7",
"r8","r9","r10","r11","r12","r13","r14","r15","r16","r17","r18",
"r19","r20","r21","r22","r23","r24","r25","r26","r27","r28","r29",
"r30","r31","f0","f1","f2","f3","f4","f5","f6","f7","f8","f9",
"f10","f11","f12","f13","f14","f15","f16","f17","f18","f19","f20",
"f21","f22","f23","f24","f25","f26","f27","f28","f29","f30","f31",
"", "pc","ps","cr","lr","ctr","xer"]
(gdb)
-data-list-register-names 1 2 3
^done,register-names=["r1","r2","r3"]
(gdb)
The `-data-list-register-values' Command
----------------------------------------
Synopsis
........
-data-list-register-values FMT [ ( REGNO )*]
Display the registers' contents. FMT is the format according to
which the registers' contents are to be returned, followed by an
optional list of numbers specifying the registers to display. A
missing list of numbers indicates that the contents of all the
registers must be returned.
Allowed formats for FMT are:
`x'
Hexadecimal
`o'
Octal
`t'
Binary
`d'
Decimal
`r'
Raw
`N'
Natural
GDB Command
...........
The corresponding GDB commands are `info reg', `info all-reg', and (in
`gdbtk') `gdb_fetch_registers'.
Example
.......
For a PPC MBX board (note: line breaks are for readability only, they
don't appear in the actual output):
(gdb)
-data-list-register-values r 64 65
^done,register-values=[{number="64",value="0xfe00a300"},
{number="65",value="0x00029002"}]
(gdb)
-data-list-register-values x
^done,register-values=[{number="0",value="0xfe0043c8"},
{number="1",value="0x3fff88"},{number="2",value="0xfffffffe"},
{number="3",value="0x0"},{number="4",value="0xa"},
{number="5",value="0x3fff68"},{number="6",value="0x3fff58"},
{number="7",value="0xfe011e98"},{number="8",value="0x2"},
{number="9",value="0xfa202820"},{number="10",value="0xfa202808"},
{number="11",value="0x1"},{number="12",value="0x0"},
{number="13",value="0x4544"},{number="14",value="0xffdfffff"},
{number="15",value="0xffffffff"},{number="16",value="0xfffffeff"},
{number="17",value="0xefffffed"},{number="18",value="0xfffffffe"},
{number="19",value="0xffffffff"},{number="20",value="0xffffffff"},
{number="21",value="0xffffffff"},{number="22",value="0xfffffff7"},
{number="23",value="0xffffffff"},{number="24",value="0xffffffff"},
{number="25",value="0xffffffff"},{number="26",value="0xfffffffb"},
{number="27",value="0xffffffff"},{number="28",value="0xf7bfffff"},
{number="29",value="0x0"},{number="30",value="0xfe010000"},
{number="31",value="0x0"},{number="32",value="0x0"},
{number="33",value="0x0"},{number="34",value="0x0"},
{number="35",value="0x0"},{number="36",value="0x0"},
{number="37",value="0x0"},{number="38",value="0x0"},
{number="39",value="0x0"},{number="40",value="0x0"},
{number="41",value="0x0"},{number="42",value="0x0"},
{number="43",value="0x0"},{number="44",value="0x0"},
{number="45",value="0x0"},{number="46",value="0x0"},
{number="47",value="0x0"},{number="48",value="0x0"},
{number="49",value="0x0"},{number="50",value="0x0"},
{number="51",value="0x0"},{number="52",value="0x0"},
{number="53",value="0x0"},{number="54",value="0x0"},
{number="55",value="0x0"},{number="56",value="0x0"},
{number="57",value="0x0"},{number="58",value="0x0"},
{number="59",value="0x0"},{number="60",value="0x0"},
{number="61",value="0x0"},{number="62",value="0x0"},
{number="63",value="0x0"},{number="64",value="0xfe00a300"},
{number="65",value="0x29002"},{number="66",value="0x202f04b5"},
{number="67",value="0xfe0043b0"},{number="68",value="0xfe00b3e4"},
{number="69",value="0x20002b03"}]
(gdb)
The `-data-read-memory' Command
-------------------------------
This command is deprecated, use `-data-read-memory-bytes' instead.
Synopsis
........
-data-read-memory [ -o BYTE-OFFSET ]
ADDRESS WORD-FORMAT WORD-SIZE
NR-ROWS NR-COLS [ ASCHAR ]
where:
`ADDRESS'
An expression specifying the address of the first memory word to be
read. Complex expressions containing embedded white space should
be quoted using the C convention.
`WORD-FORMAT'
The format to be used to print the memory words. The notation is
the same as for GDB's `print' command (*note Output Formats:
Output Formats.).
`WORD-SIZE'
The size of each memory word in bytes.
`NR-ROWS'
The number of rows in the output table.
`NR-COLS'
The number of columns in the output table.
`ASCHAR'
If present, indicates that each row should include an ASCII dump.
The value of ASCHAR is used as a padding character when a byte is
not a member of the printable ASCII character set (printable ASCII
characters are those whose code is between 32 and 126,
inclusively).
`BYTE-OFFSET'
An offset to add to the ADDRESS before fetching memory.
This command displays memory contents as a table of NR-ROWS by
NR-COLS words, each word being WORD-SIZE bytes. In total, `NR-ROWS *
NR-COLS * WORD-SIZE' bytes are read (returned as `total-bytes').
Should less than the requested number of bytes be returned by the
target, the missing words are identified using `N/A'. The number of
bytes read from the target is returned in `nr-bytes' and the starting
address used to read memory in `addr'.
The address of the next/previous row or page is available in
`next-row' and `prev-row', `next-page' and `prev-page'.
GDB Command
...........
The corresponding GDB command is `x'. `gdbtk' has `gdb_get_mem' memory
read command.
Example
.......
Read six bytes of memory starting at `bytes+6' but then offset by `-6'
bytes. Format as three rows of two columns. One byte per word.
Display each word in hex.
(gdb)
9-data-read-memory -o -6 -- bytes+6 x 1 3 2
9^done,addr="0x00001390",nr-bytes="6",total-bytes="6",
next-row="0x00001396",prev-row="0x0000138e",next-page="0x00001396",
prev-page="0x0000138a",memory=[
{addr="0x00001390",data=["0x00","0x01"]},
{addr="0x00001392",data=["0x02","0x03"]},
{addr="0x00001394",data=["0x04","0x05"]}]
(gdb)
Read two bytes of memory starting at address `shorts + 64' and
display as a single word formatted in decimal.
(gdb)
5-data-read-memory shorts+64 d 2 1 1
5^done,addr="0x00001510",nr-bytes="2",total-bytes="2",
next-row="0x00001512",prev-row="0x0000150e",
next-page="0x00001512",prev-page="0x0000150e",memory=[
{addr="0x00001510",data=["128"]}]
(gdb)
Read thirty two bytes of memory starting at `bytes+16' and format as
eight rows of four columns. Include a string encoding with `x' used as
the non-printable character.
(gdb)
4-data-read-memory bytes+16 x 1 8 4 x
4^done,addr="0x000013a0",nr-bytes="32",total-bytes="32",
next-row="0x000013c0",prev-row="0x0000139c",
next-page="0x000013c0",prev-page="0x00001380",memory=[
{addr="0x000013a0",data=["0x10","0x11","0x12","0x13"],ascii="xxxx"},
{addr="0x000013a4",data=["0x14","0x15","0x16","0x17"],ascii="xxxx"},
{addr="0x000013a8",data=["0x18","0x19","0x1a","0x1b"],ascii="xxxx"},
{addr="0x000013ac",data=["0x1c","0x1d","0x1e","0x1f"],ascii="xxxx"},
{addr="0x000013b0",data=["0x20","0x21","0x22","0x23"],ascii=" !\"#"},
{addr="0x000013b4",data=["0x24","0x25","0x26","0x27"],ascii="$%&'"},
{addr="0x000013b8",data=["0x28","0x29","0x2a","0x2b"],ascii="()*+"},
{addr="0x000013bc",data=["0x2c","0x2d","0x2e","0x2f"],ascii=",-./"}]
(gdb)
The `-data-read-memory-bytes' Command
-------------------------------------
Synopsis
........
-data-read-memory-bytes [ -o BYTE-OFFSET ]
ADDRESS COUNT
where:
`ADDRESS'
An expression specifying the address of the first memory word to be
read. Complex expressions containing embedded white space should
be quoted using the C convention.
`COUNT'
The number of bytes to read. This should be an integer literal.
`BYTE-OFFSET'
The offsets in bytes relative to ADDRESS at which to start
reading. This should be an integer literal. This option is
provided so that a frontend is not required to first evaluate
address and then perform address arithmetics itself.
This command attempts to read all accessible memory regions in the
specified range. First, all regions marked as unreadable in the memory
map (if one is defined) will be skipped. *Note Memory Region
Attributes::. Second, GDB will attempt to read the remaining regions.
For each one, if reading full region results in an errors, GDB will try
to read a subset of the region.
In general, every single byte in the region may be readable or not,
and the only way to read every readable byte is to try a read at every
address, which is not practical. Therefore, GDB will attempt to read
all accessible bytes at either beginning or the end of the region,
using a binary division scheme. This heuristic works well for reading
accross a memory map boundary. Note that if a region has a readable
range that is neither at the beginning or the end, GDB will not read it.
The result record (*note GDB/MI Result Records::) that is output of
the command includes a field named `memory' whose content is a list of
tuples. Each tuple represent a successfully read memory block and has
the following fields:
`begin'
The start address of the memory block, as hexadecimal literal.
`end'
The end address of the memory block, as hexadecimal literal.
`offset'
The offset of the memory block, as hexadecimal literal, relative to
the start address passed to `-data-read-memory-bytes'.
`contents'
The contents of the memory block, in hex.
GDB Command
...........
The corresponding GDB command is `x'.
Example
.......
(gdb)
-data-read-memory-bytes &a 10
^done,memory=[{begin="0xbffff154",offset="0x00000000",
end="0xbffff15e",
contents="01000000020000000300"}]
(gdb)
The `-data-write-memory-bytes' Command
--------------------------------------
Synopsis
........
-data-write-memory-bytes ADDRESS CONTENTS
where:
`ADDRESS'
An expression specifying the address of the first memory word to be
read. Complex expressions containing embedded white space should
be quoted using the C convention.
`CONTENTS'
The hex-encoded bytes to write.
GDB Command
...........
There's no corresponding GDB command.
Example
.......
(gdb)
-data-write-memory-bytes &a "aabbccdd"
^done
(gdb)

File: gdb.info, Node: GDB/MI Tracepoint Commands, Next: GDB/MI Symbol Query, Prev: GDB/MI Data Manipulation, Up: GDB/MI
27.16 GDB/MI Tracepoint Commands
================================
The commands defined in this section implement MI support for
tracepoints. For detailed introduction, see *Note Tracepoints::.
The `-trace-find' Command
-------------------------
Synopsis
........
-trace-find MODE [PARAMETERS...]
Find a trace frame using criteria defined by MODE and PARAMETERS.
The following table lists permissible modes and their parameters. For
details of operation, see *Note tfind::.
`none'
No parameters are required. Stops examining trace frames.
`frame-number'
An integer is required as parameter. Selects tracepoint frame with
that index.
`tracepoint-number'
An integer is required as parameter. Finds next trace frame that
corresponds to tracepoint with the specified number.
`pc'
An address is required as parameter. Finds next trace frame that
corresponds to any tracepoint at the specified address.
`pc-inside-range'
Two addresses are required as parameters. Finds next trace frame
that corresponds to a tracepoint at an address inside the
specified range. Both bounds are considered to be inside the
range.
`pc-outside-range'
Two addresses are required as parameters. Finds next trace frame
that corresponds to a tracepoint at an address outside the
specified range. Both bounds are considered to be inside the
range.
`line'
Line specification is required as parameter. *Note Specify
Location::. Finds next trace frame that corresponds to a
tracepoint at the specified location.
If `none' was passed as MODE, the response does not have fields.
Otherwise, the response may have the following fields:
`found'
This field has either `0' or `1' as the value, depending on
whether a matching tracepoint was found.
`traceframe'
The index of the found traceframe. This field is present iff the
`found' field has value of `1'.
`tracepoint'
The index of the found tracepoint. This field is present iff the
`found' field has value of `1'.
`frame'
The information about the frame corresponding to the found trace
frame. This field is present only if a trace frame was found.
*Note GDB/MI Frame Information::, for description of this field.
GDB Command
...........
The corresponding GDB command is `tfind'.
-trace-define-variable
----------------------
Synopsis
........
-trace-define-variable NAME [ VALUE ]
Create trace variable NAME if it does not exist. If VALUE is
specified, sets the initial value of the specified trace variable to
that value. Note that the NAME should start with the `$' character.
GDB Command
...........
The corresponding GDB command is `tvariable'.
-trace-list-variables
---------------------
Synopsis
........
-trace-list-variables
Return a table of all defined trace variables. Each element of the
table has the following fields:
`name'
The name of the trace variable. This field is always present.
`initial'
The initial value. This is a 64-bit signed integer. This field
is always present.
`current'
The value the trace variable has at the moment. This is a 64-bit
signed integer. This field is absent iff current value is not
defined, for example if the trace was never run, or is presently
running.
GDB Command
...........
The corresponding GDB command is `tvariables'.
Example
.......
(gdb)
-trace-list-variables
^done,trace-variables={nr_rows="1",nr_cols="3",
hdr=[{width="15",alignment="-1",col_name="name",colhdr="Name"},
{width="11",alignment="-1",col_name="initial",colhdr="Initial"},
{width="11",alignment="-1",col_name="current",colhdr="Current"}],
body=[variable={name="$trace_timestamp",initial="0"}
variable={name="$foo",initial="10",current="15"}]}
(gdb)
-trace-save
-----------
Synopsis
........
-trace-save [-r ] FILENAME
Saves the collected trace data to FILENAME. Without the `-r'
option, the data is downloaded from the target and saved in a local
file. With the `-r' option the target is asked to perform the save.
GDB Command
...........
The corresponding GDB command is `tsave'.
-trace-start
------------
Synopsis
........
-trace-start
Starts a tracing experiments. The result of this command does not
have any fields.
GDB Command
...........
The corresponding GDB command is `tstart'.
-trace-status
-------------
Synopsis
........
-trace-status
Obtains the status of a tracing experiment. The result may include
the following fields:
`supported'
May have a value of either `0', when no tracing operations are
supported, `1', when all tracing operations are supported, or
`file' when examining trace file. In the latter case, examining
of trace frame is possible but new tracing experiement cannot be
started. This field is always present.
`running'
May have a value of either `0' or `1' depending on whether tracing
experiement is in progress on target. This field is present if
`supported' field is not `0'.
`stop-reason'
Report the reason why the tracing was stopped last time. This
field may be absent iff tracing was never stopped on target yet.
The value of `request' means the tracing was stopped as result of
the `-trace-stop' command. The value of `overflow' means the
tracing buffer is full. The value of `disconnection' means
tracing was automatically stopped when GDB has disconnected. The
value of `passcount' means tracing was stopped when a tracepoint
was passed a maximal number of times for that tracepoint. This
field is present if `supported' field is not `0'.
`stopping-tracepoint'
The number of tracepoint whose passcount as exceeded. This field
is present iff the `stop-reason' field has the value of
`passcount'.
`frames'
`frames-created'
The `frames' field is a count of the total number of trace frames
in the trace buffer, while `frames-created' is the total created
during the run, including ones that were discarded, such as when a
circular trace buffer filled up. Both fields are optional.
`buffer-size'
`buffer-free'
These fields tell the current size of the tracing buffer and the
remaining space. These fields are optional.
`circular'
The value of the circular trace buffer flag. `1' means that the
trace buffer is circular and old trace frames will be discarded if
necessary to make room, `0' means that the trace buffer is linear
and may fill up.
`disconnected'
The value of the disconnected tracing flag. `1' means that
tracing will continue after GDB disconnects, `0' means that the
trace run will stop.
GDB Command
...........
The corresponding GDB command is `tstatus'.
-trace-stop
-----------
Synopsis
........
-trace-stop
Stops a tracing experiment. The result of this command has the same
fields as `-trace-status', except that the `supported' and `running'
fields are not output.
GDB Command
...........
The corresponding GDB command is `tstop'.

File: gdb.info, Node: GDB/MI Symbol Query, Next: GDB/MI File Commands, Prev: GDB/MI Tracepoint Commands, Up: GDB/MI
27.17 GDB/MI Symbol Query Commands
==================================
The `-symbol-list-lines' Command
--------------------------------
Synopsis
........
-symbol-list-lines FILENAME
Print the list of lines that contain code and their associated
program addresses for the given source filename. The entries are
sorted in ascending PC order.
GDB Command
...........
There is no corresponding GDB command.
Example
.......
(gdb)
-symbol-list-lines basics.c
^done,lines=[{pc="0x08048554",line="7"},{pc="0x0804855a",line="8"}]
(gdb)

File: gdb.info, Node: GDB/MI File Commands, Next: GDB/MI Target Manipulation, Prev: GDB/MI Symbol Query, Up: GDB/MI
27.18 GDB/MI File Commands
==========================
This section describes the GDB/MI commands to specify executable file
names and to read in and obtain symbol table information.
The `-file-exec-and-symbols' Command
------------------------------------
Synopsis
........
-file-exec-and-symbols FILE
Specify the executable file to be debugged. This file is the one
from which the symbol table is also read. If no file is specified, the
command clears the executable and symbol information. If breakpoints
are set when using this command with no arguments, GDB will produce
error messages. Otherwise, no output is produced, except a completion
notification.
GDB Command
...........
The corresponding GDB command is `file'.
Example
.......
(gdb)
-file-exec-and-symbols /kwikemart/marge/ezannoni/TRUNK/mbx/hello.mbx
^done
(gdb)
The `-file-exec-file' Command
-----------------------------
Synopsis
........
-file-exec-file FILE
Specify the executable file to be debugged. Unlike
`-file-exec-and-symbols', the symbol table is _not_ read from this
file. If used without argument, GDB clears the information about the
executable file. No output is produced, except a completion
notification.
GDB Command
...........
The corresponding GDB command is `exec-file'.
Example
.......
(gdb)
-file-exec-file /kwikemart/marge/ezannoni/TRUNK/mbx/hello.mbx
^done
(gdb)
The `-file-list-exec-source-file' Command
-----------------------------------------
Synopsis
........
-file-list-exec-source-file
List the line number, the current source file, and the absolute path
to the current source file for the current executable. The macro
information field has a value of `1' or `0' depending on whether or not
the file includes preprocessor macro information.
GDB Command
...........
The GDB equivalent is `info source'
Example
.......
(gdb)
123-file-list-exec-source-file
123^done,line="1",file="foo.c",fullname="/home/bar/foo.c,macro-info="1"
(gdb)
The `-file-list-exec-source-files' Command
------------------------------------------
Synopsis
........
-file-list-exec-source-files
List the source files for the current executable.
It will always output the filename, but only when GDB can find the
absolute file name of a source file, will it output the fullname.
GDB Command
...........
The GDB equivalent is `info sources'. `gdbtk' has an analogous command
`gdb_listfiles'.
Example
.......
(gdb)
-file-list-exec-source-files
^done,files=[
{file=foo.c,fullname=/home/foo.c},
{file=/home/bar.c,fullname=/home/bar.c},
{file=gdb_could_not_find_fullpath.c}]
(gdb)
The `-file-symbol-file' Command
-------------------------------
Synopsis
........
-file-symbol-file FILE
Read symbol table info from the specified FILE argument. When used
without arguments, clears GDB's symbol table info. No output is
produced, except for a completion notification.
GDB Command
...........
The corresponding GDB command is `symbol-file'.
Example
.......
(gdb)
-file-symbol-file /kwikemart/marge/ezannoni/TRUNK/mbx/hello.mbx
^done
(gdb)

File: gdb.info, Node: GDB/MI Target Manipulation, Next: GDB/MI File Transfer Commands, Prev: GDB/MI File Commands, Up: GDB/MI
27.19 GDB/MI Target Manipulation Commands
=========================================
The `-target-attach' Command
----------------------------
Synopsis
........
-target-attach PID | GID | FILE
Attach to a process PID or a file FILE outside of GDB, or a thread
group GID. If attaching to a thread group, the id previously returned
by `-list-thread-groups --available' must be used.
GDB Command
...........
The corresponding GDB command is `attach'.
Example
.......
(gdb)
-target-attach 34
=thread-created,id="1"
*stopped,thread-id="1",frame={addr="0xb7f7e410",func="bar",args=[]}
^done
(gdb)
The `-target-detach' Command
----------------------------
Synopsis
........
-target-detach [ PID | GID ]
Detach from the remote target which normally resumes its execution.
If either PID or GID is specified, detaches from either the specified
process, or specified thread group. There's no output.
GDB Command
...........
The corresponding GDB command is `detach'.
Example
.......
(gdb)
-target-detach
^done
(gdb)
The `-target-disconnect' Command
--------------------------------
Synopsis
........
-target-disconnect
Disconnect from the remote target. There's no output and the target
is generally not resumed.
GDB Command
...........
The corresponding GDB command is `disconnect'.
Example
.......
(gdb)
-target-disconnect
^done
(gdb)
The `-target-download' Command
------------------------------
Synopsis
........
-target-download
Loads the executable onto the remote target. It prints out an
update message every half second, which includes the fields:
`section'
The name of the section.
`section-sent'
The size of what has been sent so far for that section.
`section-size'
The size of the section.
`total-sent'
The total size of what was sent so far (the current and the
previous sections).
`total-size'
The size of the overall executable to download.
Each message is sent as status record (*note GDB/MI Output Syntax:
GDB/MI Output Syntax.).
In addition, it prints the name and size of the sections, as they are
downloaded. These messages include the following fields:
`section'
The name of the section.
`section-size'
The size of the section.
`total-size'
The size of the overall executable to download.
At the end, a summary is printed.
GDB Command
...........
The corresponding GDB command is `load'.
Example
.......
Note: each status message appears on a single line. Here the messages
have been broken down so that they can fit onto a page.
(gdb)
-target-download
+download,{section=".text",section-size="6668",total-size="9880"}
+download,{section=".text",section-sent="512",section-size="6668",
total-sent="512",total-size="9880"}
+download,{section=".text",section-sent="1024",section-size="6668",
total-sent="1024",total-size="9880"}
+download,{section=".text",section-sent="1536",section-size="6668",
total-sent="1536",total-size="9880"}
+download,{section=".text",section-sent="2048",section-size="6668",
total-sent="2048",total-size="9880"}
+download,{section=".text",section-sent="2560",section-size="6668",
total-sent="2560",total-size="9880"}
+download,{section=".text",section-sent="3072",section-size="6668",
total-sent="3072",total-size="9880"}
+download,{section=".text",section-sent="3584",section-size="6668",
total-sent="3584",total-size="9880"}
+download,{section=".text",section-sent="4096",section-size="6668",
total-sent="4096",total-size="9880"}
+download,{section=".text",section-sent="4608",section-size="6668",
total-sent="4608",total-size="9880"}
+download,{section=".text",section-sent="5120",section-size="6668",
total-sent="5120",total-size="9880"}
+download,{section=".text",section-sent="5632",section-size="6668",
total-sent="5632",total-size="9880"}
+download,{section=".text",section-sent="6144",section-size="6668",
total-sent="6144",total-size="9880"}
+download,{section=".text",section-sent="6656",section-size="6668",
total-sent="6656",total-size="9880"}
+download,{section=".init",section-size="28",total-size="9880"}
+download,{section=".fini",section-size="28",total-size="9880"}
+download,{section=".data",section-size="3156",total-size="9880"}
+download,{section=".data",section-sent="512",section-size="3156",
total-sent="7236",total-size="9880"}
+download,{section=".data",section-sent="1024",section-size="3156",
total-sent="7748",total-size="9880"}
+download,{section=".data",section-sent="1536",section-size="3156",
total-sent="8260",total-size="9880"}
+download,{section=".data",section-sent="2048",section-size="3156",
total-sent="8772",total-size="9880"}
+download,{section=".data",section-sent="2560",section-size="3156",
total-sent="9284",total-size="9880"}
+download,{section=".data",section-sent="3072",section-size="3156",
total-sent="9796",total-size="9880"}
^done,address="0x10004",load-size="9880",transfer-rate="6586",
write-rate="429"
(gdb)
GDB Command
...........
No equivalent.
Example
.......
N.A.
The `-target-select' Command
----------------------------
Synopsis
........
-target-select TYPE PARAMETERS ...
Connect GDB to the remote target. This command takes two args:
`TYPE'
The type of target, for instance `remote', etc.
`PARAMETERS'
Device names, host names and the like. *Note Commands for
Managing Targets: Target Commands, for more details.
The output is a connection notification, followed by the address at
which the target program is, in the following form:
^connected,addr="ADDRESS",func="FUNCTION NAME",
args=[ARG LIST]
GDB Command
...........
The corresponding GDB command is `target'.
Example
.......
(gdb)
-target-select remote /dev/ttya
^connected,addr="0xfe00a300",func="??",args=[]
(gdb)

File: gdb.info, Node: GDB/MI File Transfer Commands, Next: GDB/MI Miscellaneous Commands, Prev: GDB/MI Target Manipulation, Up: GDB/MI
27.20 GDB/MI File Transfer Commands
===================================
The `-target-file-put' Command
------------------------------
Synopsis
........
-target-file-put HOSTFILE TARGETFILE
Copy file HOSTFILE from the host system (the machine running GDB) to
TARGETFILE on the target system.
GDB Command
...........
The corresponding GDB command is `remote put'.
Example
.......
(gdb)
-target-file-put localfile remotefile
^done
(gdb)
The `-target-file-get' Command
------------------------------
Synopsis
........
-target-file-get TARGETFILE HOSTFILE
Copy file TARGETFILE from the target system to HOSTFILE on the host
system.
GDB Command
...........
The corresponding GDB command is `remote get'.
Example
.......
(gdb)
-target-file-get remotefile localfile
^done
(gdb)
The `-target-file-delete' Command
---------------------------------
Synopsis
........
-target-file-delete TARGETFILE
Delete TARGETFILE from the target system.
GDB Command
...........
The corresponding GDB command is `remote delete'.
Example
.......
(gdb)
-target-file-delete remotefile
^done
(gdb)

File: gdb.info, Node: GDB/MI Miscellaneous Commands, Prev: GDB/MI File Transfer Commands, Up: GDB/MI
27.21 Miscellaneous GDB/MI Commands
===================================
The `-gdb-exit' Command
-----------------------
Synopsis
........
-gdb-exit
Exit GDB immediately.
GDB Command
...........
Approximately corresponds to `quit'.
Example
.......
(gdb)
-gdb-exit
^exit
The `-gdb-set' Command
----------------------
Synopsis
........
-gdb-set
Set an internal GDB variable.
GDB Command
...........
The corresponding GDB command is `set'.
Example
.......
(gdb)
-gdb-set $foo=3
^done
(gdb)
The `-gdb-show' Command
-----------------------
Synopsis
........
-gdb-show
Show the current value of a GDB variable.
GDB Command
...........
The corresponding GDB command is `show'.
Example
.......
(gdb)
-gdb-show annotate
^done,value="0"
(gdb)
The `-gdb-version' Command
--------------------------
Synopsis
........
-gdb-version
Show version information for GDB. Used mostly in testing.
GDB Command
...........
The GDB equivalent is `show version'. GDB by default shows this
information when you start an interactive session.
Example
.......
(gdb)
-gdb-version
~GNU gdb 5.2.1
~Copyright 2000 Free Software Foundation, Inc.
~GDB is free software, covered by the GNU General Public License, and
~you are welcome to change it and/or 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.
~This GDB was configured as
"--host=sparc-sun-solaris2.5.1 --target=ppc-eabi".
^done
(gdb)
The `-list-features' Command
----------------------------
Returns a list of particular features of the MI protocol that this
version of gdb implements. A feature can be a command, or a new field
in an output of some command, or even an important bugfix. While a
frontend can sometimes detect presence of a feature at runtime, it is
easier to perform detection at debugger startup.
The command returns a list of strings, with each string naming an
available feature. Each returned string is just a name, it does not
have any internal structure. The list of possible feature names is
given below.
Example output:
(gdb) -list-features
^done,result=["feature1","feature2"]
The current list of features is:
`frozen-varobjs'
Indicates support for the `-var-set-frozen' command, as well as
possible presense of the `frozen' field in the output of
`-varobj-create'.
`pending-breakpoints'
Indicates support for the `-f' option to the `-break-insert'
command.
`python'
Indicates Python scripting support, Python-based pretty-printing
commands, and possible presence of the `display_hint' field in the
output of `-var-list-children'
`thread-info'
Indicates support for the `-thread-info' command.
`data-read-memory-bytes'
Indicates support for the `-data-read-memory-bytes' and the
`-data-write-memory-bytes' commands.
`breakpoint-notifications'
Indicates that changes to breakpoints and breakpoints created via
the CLI will be announced via async records.
`ada-task-info'
Indicates support for the `-ada-task-info' command.
The `-list-target-features' Command
-----------------------------------
Returns a list of particular features that are supported by the target.
Those features affect the permitted MI commands, but unlike the
features reported by the `-list-features' command, the features depend
on which target GDB is using at the moment. Whenever a target can
change, due to commands such as `-target-select', `-target-attach' or
`-exec-run', the list of target features may change, and the frontend
should obtain it again. Example output:
(gdb) -list-features
^done,result=["async"]
The current list of features is:
`async'
Indicates that the target is capable of asynchronous command
execution, which means that GDB will accept further commands while
the target is running.
`reverse'
Indicates that the target is capable of reverse execution. *Note
Reverse Execution::, for more information.
The `-list-thread-groups' Command
---------------------------------
Synopsis
--------
-list-thread-groups [ --available ] [ --recurse 1 ] [ GROUP ... ]
Lists thread groups (*note Thread groups::). When a single thread
group is passed as the argument, lists the children of that group.
When several thread group are passed, lists information about those
thread groups. Without any parameters, lists information about all
top-level thread groups.
Normally, thread groups that are being debugged are reported. With
the `--available' option, GDB reports thread groups available on the
target.
The output of this command may have either a `threads' result or a
`groups' result. The `thread' result has a list of tuples as value,
with each tuple describing a thread (*note GDB/MI Thread
Information::). The `groups' result has a list of tuples as value,
each tuple describing a thread group. If top-level groups are
requested (that is, no parameter is passed), or when several groups are
passed, the output always has a `groups' result. The format of the
`group' result is described below.
To reduce the number of roundtrips it's possible to list thread
groups together with their children, by passing the `--recurse' option
and the recursion depth. Presently, only recursion depth of 1 is
permitted. If this option is present, then every reported thread group
will also include its children, either as `group' or `threads' field.
In general, any combination of option and parameters is permitted,
with the following caveats:
* When a single thread group is passed, the output will typically be
the `threads' result. Because threads may not contain anything,
the `recurse' option will be ignored.
* When the `--available' option is passed, limited information may
be available. In particular, the list of threads of a process
might be inaccessible. Further, specifying specific thread groups
might not give any performance advantage over listing all thread
groups. The frontend should assume that `-list-thread-groups
--available' is always an expensive operation and cache the
results.
The `groups' result is a list of tuples, where each tuple may have
the following fields:
`id'
Identifier of the thread group. This field is always present.
The identifier is an opaque string; frontends should not try to
convert it to an integer, even though it might look like one.
`type'
The type of the thread group. At present, only `process' is a
valid type.
`pid'
The target-specific process identifier. This field is only present
for thread groups of type `process' and only if the process exists.
`num_children'
The number of children this thread group has. This field may be
absent for an available thread group.
`threads'
This field has a list of tuples as value, each tuple describing a
thread. It may be present if the `--recurse' option is specified,
and it's actually possible to obtain the threads.
`cores'
This field is a list of integers, each identifying a core that one
thread of the group is running on. This field may be absent if
such information is not available.
`executable'
The name of the executable file that corresponds to this thread
group. The field is only present for thread groups of type
`process', and only if there is a corresponding executable file.
Example
-------
gdb
-list-thread-groups
^done,groups=[{id="17",type="process",pid="yyy",num_children="2"}]
-list-thread-groups 17
^done,threads=[{id="2",target-id="Thread 0xb7e14b90 (LWP 21257)",
frame={level="0",addr="0xffffe410",func="__kernel_vsyscall",args=[]},state="running"},
{id="1",target-id="Thread 0xb7e156b0 (LWP 21254)",
frame={level="0",addr="0x0804891f",func="foo",args=[{name="i",value="10"}],
file="/tmp/a.c",fullname="/tmp/a.c",line="158"},state="running"}]]
-list-thread-groups --available
^done,groups=[{id="17",type="process",pid="yyy",num_children="2",cores=[1,2]}]
-list-thread-groups --available --recurse 1
^done,groups=[{id="17", types="process",pid="yyy",num_children="2",cores=[1,2],
threads=[{id="1",target-id="Thread 0xb7e14b90",cores=[1]},
{id="2",target-id="Thread 0xb7e14b90",cores=[2]}]},..]
-list-thread-groups --available --recurse 1 17 18
^done,groups=[{id="17", types="process",pid="yyy",num_children="2",cores=[1,2],
threads=[{id="1",target-id="Thread 0xb7e14b90",cores=[1]},
{id="2",target-id="Thread 0xb7e14b90",cores=[2]}]},...]
The `-info-os' Command
----------------------
Synopsis
........
-info-os [ TYPE ]
If no argument is supplied, the command returns a table of available
operating-system-specific information types. If one of these types is
supplied as an argument TYPE, then the command returns a table of data
of that type.
The types of information available depend on the target operating
system.
GDB Command
...........
The corresponding GDB command is `info os'.
Example
.......
When run on a GNU/Linux system, the output will look something like
this:
gdb
-info-os
^done,OSDataTable={nr_rows="9",nr_cols="3",
hdr=[{width="10",alignment="-1",col_name="col0",colhdr="Type"},
{width="10",alignment="-1",col_name="col1",colhdr="Description"},
{width="10",alignment="-1",col_name="col2",colhdr="Title"}],
body=[item={col0="processes",col1="Listing of all processes",
col2="Processes"},
item={col0="procgroups",col1="Listing of all process groups",
col2="Process groups"},
item={col0="threads",col1="Listing of all threads",
col2="Threads"},
item={col0="files",col1="Listing of all file descriptors",
col2="File descriptors"},
item={col0="sockets",col1="Listing of all internet-domain sockets",
col2="Sockets"},
item={col0="shm",col1="Listing of all shared-memory regions",
col2="Shared-memory regions"},
item={col0="semaphores",col1="Listing of all semaphores",
col2="Semaphores"},
item={col0="msg",col1="Listing of all message queues",
col2="Message queues"},
item={col0="modules",col1="Listing of all loaded kernel modules",
col2="Kernel modules"}]}
gdb
-info-os processes
^done,OSDataTable={nr_rows="190",nr_cols="4",
hdr=[{width="10",alignment="-1",col_name="col0",colhdr="pid"},
{width="10",alignment="-1",col_name="col1",colhdr="user"},
{width="10",alignment="-1",col_name="col2",colhdr="command"},
{width="10",alignment="-1",col_name="col3",colhdr="cores"}],
body=[item={col0="1",col1="root",col2="/sbin/init",col3="0"},
item={col0="2",col1="root",col2="[kthreadd]",col3="1"},
item={col0="3",col1="root",col2="[ksoftirqd/0]",col3="0"},
...
item={col0="26446",col1="stan",col2="bash",col3="0"},
item={col0="28152",col1="stan",col2="bash",col3="1"}]}
(gdb)
(Note that the MI output here includes a `"Title"' column that does
not appear in command-line `info os'; this column is useful for MI
clients that want to enumerate the types of data, such as in a popup
menu, but is needless clutter on the command line, and `info os' omits
it.)
The `-add-inferior' Command
---------------------------
Synopsis
--------
-add-inferior
Creates a new inferior (*note Inferiors and Programs::). The created
inferior is not associated with any executable. Such association may
be established with the `-file-exec-and-symbols' command (*note GDB/MI
File Commands::). The command response has a single field,
`thread-group', whose value is the identifier of the thread group
corresponding to the new inferior.
Example
-------
gdb
-add-inferior
^done,thread-group="i3"
The `-interpreter-exec' Command
-------------------------------
Synopsis
--------
-interpreter-exec INTERPRETER COMMAND
Execute the specified COMMAND in the given INTERPRETER.
GDB Command
-----------
The corresponding GDB command is `interpreter-exec'.
Example
-------
(gdb)
-interpreter-exec console "break main"
&"During symbol reading, couldn't parse type; debugger out of date?.\n"
&"During symbol reading, bad structure-type format.\n"
~"Breakpoint 1 at 0x8074fc6: file ../../src/gdb/main.c, line 743.\n"
^done
(gdb)
The `-inferior-tty-set' Command
-------------------------------
Synopsis
--------
-inferior-tty-set /dev/pts/1
Set terminal for future runs of the program being debugged.
GDB Command
-----------
The corresponding GDB command is `set inferior-tty' /dev/pts/1.
Example
-------
(gdb)
-inferior-tty-set /dev/pts/1
^done
(gdb)
The `-inferior-tty-show' Command
--------------------------------
Synopsis
--------
-inferior-tty-show
Show terminal for future runs of program being debugged.
GDB Command
-----------
The corresponding GDB command is `show inferior-tty'.
Example
-------
(gdb)
-inferior-tty-set /dev/pts/1
^done
(gdb)
-inferior-tty-show
^done,inferior_tty_terminal="/dev/pts/1"
(gdb)
The `-enable-timings' Command
-----------------------------
Synopsis
--------
-enable-timings [yes | no]
Toggle the printing of the wallclock, user and system times for an MI
command as a field in its output. This command is to help frontend
developers optimize the performance of their code. No argument is
equivalent to `yes'.
GDB Command
-----------
No equivalent.
Example
-------
(gdb)
-enable-timings
^done
(gdb)
-break-insert main
^done,bkpt={number="1",type="breakpoint",disp="keep",enabled="y",
addr="0x080484ed",func="main",file="myprog.c",
fullname="/home/nickrob/myprog.c",line="73",times="0"},
time={wallclock="0.05185",user="0.00800",system="0.00000"}
(gdb)
-enable-timings no
^done
(gdb)
-exec-run
^running
(gdb)
*stopped,reason="breakpoint-hit",disp="keep",bkptno="1",thread-id="0",
frame={addr="0x080484ed",func="main",args=[{name="argc",value="1"},
{name="argv",value="0xbfb60364"}],file="myprog.c",
fullname="/home/nickrob/myprog.c",line="73"}
(gdb)

File: gdb.info, Node: Annotations, Next: JIT Interface, Prev: GDB/MI, Up: Top
28 GDB Annotations
******************
This chapter describes annotations in GDB. Annotations were designed
to interface GDB to graphical user interfaces or other similar programs
which want to interact with GDB at a relatively high level.
The annotation mechanism has largely been superseded by GDB/MI
(*note GDB/MI::).
* Menu:
* Annotations Overview:: What annotations are; the general syntax.
* Server Prefix:: Issuing a command without affecting user state.
* Prompting:: Annotations marking GDB's need for input.
* Errors:: Annotations for error messages.
* Invalidation:: Some annotations describe things now invalid.
* Annotations for Running::
Whether the program is running, how it stopped, etc.
* Source Annotations:: Annotations describing source code.

File: gdb.info, Node: Annotations Overview, Next: Server Prefix, Up: Annotations
28.1 What is an Annotation?
===========================
Annotations start with a newline character, two `control-z' characters,
and the name of the annotation. If there is no additional information
associated with this annotation, the name of the annotation is followed
immediately by a newline. If there is additional information, the name
of the annotation is followed by a space, the additional information,
and a newline. The additional information cannot contain newline
characters.
Any output not beginning with a newline and two `control-z'
characters denotes literal output from GDB. Currently there is no need
for GDB to output a newline followed by two `control-z' characters, but
if there was such a need, the annotations could be extended with an
`escape' annotation which means those three characters as output.
The annotation LEVEL, which is specified using the `--annotate'
command line option (*note Mode Options::), controls how much
information GDB prints together with its prompt, values of expressions,
source lines, and other types of output. Level 0 is for no
annotations, level 1 is for use when GDB is run as a subprocess of GNU
Emacs, level 3 is the maximum annotation suitable for programs that
control GDB, and level 2 annotations have been made obsolete (*note
Limitations of the Annotation Interface: (annotate)Limitations.).
`set annotate LEVEL'
The GDB command `set annotate' sets the level of annotations to
the specified LEVEL.
`show annotate'
Show the current annotation level.
This chapter describes level 3 annotations.
A simple example of starting up GDB with annotations is:
$ gdb --annotate=3
GNU gdb 6.0
Copyright 2003 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License,
and you are welcome to change it and/or 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.
This GDB was configured as "i386-pc-linux-gnu"
^Z^Zpre-prompt
(gdb)
^Z^Zprompt
quit
^Z^Zpost-prompt
$
Here `quit' is input to GDB; the rest is output from GDB. The three
lines beginning `^Z^Z' (where `^Z' denotes a `control-z' character) are
annotations; the rest is output from GDB.

File: gdb.info, Node: Server Prefix, Next: Prompting, Prev: Annotations Overview, Up: Annotations
28.2 The Server Prefix
======================
If you prefix a command with `server ' then it will not affect the
command history, nor will it affect GDB's notion of which command to
repeat if <RET> is pressed on a line by itself. This means that
commands can be run behind a user's back by a front-end in a
transparent manner.
The `server ' prefix does not affect the recording of values into
the value history; to print a value without recording it into the value
history, use the `output' command instead of the `print' command.
Using this prefix also disables confirmation requests (*note
confirmation requests::).

File: gdb.info, Node: Prompting, Next: Errors, Prev: Server Prefix, Up: Annotations
28.3 Annotation for GDB Input
=============================
When GDB prompts for input, it annotates this fact so it is possible to
know when to send output, when the output from a given command is over,
etc.
Different kinds of input each have a different "input type". Each
input type has three annotations: a `pre-' annotation, which denotes
the beginning of any prompt which is being output, a plain annotation,
which denotes the end of the prompt, and then a `post-' annotation
which denotes the end of any echo which may (or may not) be associated
with the input. For example, the `prompt' input type features the
following annotations:
^Z^Zpre-prompt
^Z^Zprompt
^Z^Zpost-prompt
The input types are
`prompt'
When GDB is prompting for a command (the main GDB prompt).
`commands'
When GDB prompts for a set of commands, like in the `commands'
command. The annotations are repeated for each command which is
input.
`overload-choice'
When GDB wants the user to select between various overloaded
functions.
`query'
When GDB wants the user to confirm a potentially dangerous
operation.
`prompt-for-continue'
When GDB is asking the user to press return to continue. Note:
Don't expect this to work well; instead use `set height 0' to
disable prompting. This is because the counting of lines is buggy
in the presence of annotations.

File: gdb.info, Node: Errors, Next: Invalidation, Prev: Prompting, Up: Annotations
28.4 Errors
===========
^Z^Zquit
This annotation occurs right before GDB responds to an interrupt.
^Z^Zerror
This annotation occurs right before GDB responds to an error.
Quit and error annotations indicate that any annotations which GDB
was in the middle of may end abruptly. For example, if a
`value-history-begin' annotation is followed by a `error', one cannot
expect to receive the matching `value-history-end'. One cannot expect
not to receive it either, however; an error annotation does not
necessarily mean that GDB is immediately returning all the way to the
top level.
A quit or error annotation may be preceded by
^Z^Zerror-begin
Any output between that and the quit or error annotation is the error
message.
Warning messages are not yet annotated.

File: gdb.info, Node: Invalidation, Next: Annotations for Running, Prev: Errors, Up: Annotations
28.5 Invalidation Notices
=========================
The following annotations say that certain pieces of state may have
changed.
`^Z^Zframes-invalid'
The frames (for example, output from the `backtrace' command) may
have changed.
`^Z^Zbreakpoints-invalid'
The breakpoints may have changed. For example, the user just
added or deleted a breakpoint.

File: gdb.info, Node: Annotations for Running, Next: Source Annotations, Prev: Invalidation, Up: Annotations
28.6 Running the Program
========================
When the program starts executing due to a GDB command such as `step'
or `continue',
^Z^Zstarting
is output. When the program stops,
^Z^Zstopped
is output. Before the `stopped' annotation, a variety of
annotations describe how the program stopped.
`^Z^Zexited EXIT-STATUS'
The program exited, and EXIT-STATUS is the exit status (zero for
successful exit, otherwise nonzero).
`^Z^Zsignalled'
The program exited with a signal. After the `^Z^Zsignalled', the
annotation continues:
INTRO-TEXT
^Z^Zsignal-name
NAME
^Z^Zsignal-name-end
MIDDLE-TEXT
^Z^Zsignal-string
STRING
^Z^Zsignal-string-end
END-TEXT
where NAME is the name of the signal, such as `SIGILL' or
`SIGSEGV', and STRING is the explanation of the signal, such as
`Illegal Instruction' or `Segmentation fault'. INTRO-TEXT,
MIDDLE-TEXT, and END-TEXT are for the user's benefit and have no
particular format.
`^Z^Zsignal'
The syntax of this annotation is just like `signalled', but GDB is
just saying that the program received the signal, not that it was
terminated with it.
`^Z^Zbreakpoint NUMBER'
The program hit breakpoint number NUMBER.
`^Z^Zwatchpoint NUMBER'
The program hit watchpoint number NUMBER.

File: gdb.info, Node: Source Annotations, Prev: Annotations for Running, Up: Annotations
28.7 Displaying Source
======================
The following annotation is used instead of displaying source code:
^Z^Zsource FILENAME:LINE:CHARACTER:MIDDLE:ADDR
where FILENAME is an absolute file name indicating which source
file, LINE is the line number within that file (where 1 is the first
line in the file), CHARACTER is the character position within the file
(where 0 is the first character in the file) (for most debug formats
this will necessarily point to the beginning of a line), MIDDLE is
`middle' if ADDR is in the middle of the line, or `beg' if ADDR is at
the beginning of the line, and ADDR is the address in the target
program associated with the source which is being displayed. ADDR is
in the form `0x' followed by one or more lowercase hex digits (note
that this does not depend on the language).

File: gdb.info, Node: JIT Interface, Next: In-Process Agent, Prev: Annotations, Up: Top
29 JIT Compilation Interface
****************************
This chapter documents GDB's "just-in-time" (JIT) compilation
interface. A JIT compiler is a program or library that generates native
executable code at runtime and executes it, usually in order to achieve
good performance while maintaining platform independence.
Programs that use JIT compilation are normally difficult to debug
because portions of their code are generated at runtime, instead of
being loaded from object files, which is where GDB normally finds the
program's symbols and debug information. In order to debug programs
that use JIT compilation, GDB has an interface that allows the program
to register in-memory symbol files with GDB at runtime.
If you are using GDB to debug a program that uses this interface,
then it should work transparently so long as you have not stripped the
binary. If you are developing a JIT compiler, then the interface is
documented in the rest of this chapter. At this time, the only known
client of this interface is the LLVM JIT.
Broadly speaking, the JIT interface mirrors the dynamic loader
interface. The JIT compiler communicates with GDB by writing data into
a global variable and calling a fuction at a well-known symbol. When
GDB attaches, it reads a linked list of symbol files from the global
variable to find existing code, and puts a breakpoint in the function
so that it can find out about additional code.
* Menu:
* Declarations:: Relevant C struct declarations
* Registering Code:: Steps to register code
* Unregistering Code:: Steps to unregister code
* Custom Debug Info:: Emit debug information in a custom format

File: gdb.info, Node: Declarations, Next: Registering Code, Up: JIT Interface
29.1 JIT Declarations
=====================
These are the relevant struct declarations that a C program should
include to implement the interface:
typedef enum
{
JIT_NOACTION = 0,
JIT_REGISTER_FN,
JIT_UNREGISTER_FN
} jit_actions_t;
struct jit_code_entry
{
struct jit_code_entry *next_entry;
struct jit_code_entry *prev_entry;
const char *symfile_addr;
uint64_t symfile_size;
};
struct jit_descriptor
{
uint32_t version;
/* This type should be jit_actions_t, but we use uint32_t
to be explicit about the bitwidth. */
uint32_t action_flag;
struct jit_code_entry *relevant_entry;
struct jit_code_entry *first_entry;
};
/* GDB puts a breakpoint in this function. */
void __attribute__((noinline)) __jit_debug_register_code() { };
/* Make sure to specify the version statically, because the
debugger may check the version before we can set it. */
struct jit_descriptor __jit_debug_descriptor = { 1, 0, 0, 0 };
If the JIT is multi-threaded, then it is important that the JIT
synchronize any modifications to this global data properly, which can
easily be done by putting a global mutex around modifications to these
structures.

File: gdb.info, Node: Registering Code, Next: Unregistering Code, Prev: Declarations, Up: JIT Interface
29.2 Registering Code
=====================
To register code with GDB, the JIT should follow this protocol:
* Generate an object file in memory with symbols and other desired
debug information. The file must include the virtual addresses of
the sections.
* Create a code entry for the file, which gives the start and size
of the symbol file.
* Add it to the linked list in the JIT descriptor.
* Point the relevant_entry field of the descriptor at the entry.
* Set `action_flag' to `JIT_REGISTER' and call
`__jit_debug_register_code'.
When GDB is attached and the breakpoint fires, GDB uses the
`relevant_entry' pointer so it doesn't have to walk the list looking for
new code. However, the linked list must still be maintained in order
to allow GDB to attach to a running process and still find the symbol
files.

File: gdb.info, Node: Unregistering Code, Next: Custom Debug Info, Prev: Registering Code, Up: JIT Interface
29.3 Unregistering Code
=======================
If code is freed, then the JIT should use the following protocol:
* Remove the code entry corresponding to the code from the linked
list.
* Point the `relevant_entry' field of the descriptor at the code
entry.
* Set `action_flag' to `JIT_UNREGISTER' and call
`__jit_debug_register_code'.
If the JIT frees or recompiles code without unregistering it, then
GDB and the JIT will leak the memory used for the associated symbol
files.

File: gdb.info, Node: Custom Debug Info, Prev: Unregistering Code, Up: JIT Interface
29.4 Custom Debug Info
======================
Generating debug information in platform-native file formats (like ELF
or COFF) may be an overkill for JIT compilers; especially if all the
debug info is used for is displaying a meaningful backtrace. The issue
can be resolved by having the JIT writers decide on a debug info format
and also provide a reader that parses the debug info generated by the
JIT compiler. This section gives a brief overview on writing such a
parser. More specific details can be found in the source file
`gdb/jit-reader.in', which is also installed as a header at
`INCLUDEDIR/gdb/jit-reader.h' for easy inclusion.
The reader is implemented as a shared object (so this functionality
is not available on platforms which don't allow loading shared objects
at runtime). Two GDB commands, `jit-reader-load' and
`jit-reader-unload' are provided, to be used to load and unload the
readers from a preconfigured directory. Once loaded, the shared object
is used the parse the debug information emitted by the JIT compiler.
* Menu:
* Using JIT Debug Info Readers:: How to use supplied readers correctly
* Writing JIT Debug Info Readers:: Creating a debug-info reader

File: gdb.info, Node: Using JIT Debug Info Readers, Next: Writing JIT Debug Info Readers, Up: Custom Debug Info
29.4.1 Using JIT Debug Info Readers
-----------------------------------
Readers can be loaded and unloaded using the `jit-reader-load' and
`jit-reader-unload' commands.
`jit-reader-load READER-NAME'
Load the JIT reader named READER-NAME. On a UNIX system, this
will usually load `LIBDIR/gdb/READER-NAME', where LIBDIR is the
system library directory, usually `/usr/local/lib'. Only one
reader can be active at a time; trying to load a second reader
when one is already loaded will result in GDB reporting an error.
A new JIT reader can be loaded by first unloading the current one
using `jit-reader-load' and then invoking `jit-reader-load'.
`jit-reader-unload'
Unload the currently loaded JIT reader.

File: gdb.info, Node: Writing JIT Debug Info Readers, Prev: Using JIT Debug Info Readers, Up: Custom Debug Info
29.4.2 Writing JIT Debug Info Readers
-------------------------------------
As mentioned, a reader is essentially a shared object conforming to a
certain ABI. This ABI is described in `jit-reader.h'.
`jit-reader.h' defines the structures, macros and functions required
to write a reader. It is installed (along with GDB), in
`INCLUDEDIR/gdb' where INCLUDEDIR is the system include directory.
Readers need to be released under a GPL compatible license. A reader
can be declared as released under such a license by placing the macro
`GDB_DECLARE_GPL_COMPATIBLE_READER' in a source file.
The entry point for readers is the symbol `gdb_init_reader', which
is expected to be a function with the prototype
extern struct gdb_reader_funcs *gdb_init_reader (void);
`struct gdb_reader_funcs' contains a set of pointers to callback
functions. These functions are executed to read the debug info
generated by the JIT compiler (`read'), to unwind stack frames
(`unwind') and to create canonical frame IDs (`get_Frame_id'). It also
has a callback that is called when the reader is being unloaded
(`destroy'). The struct looks like this
struct gdb_reader_funcs
{
/* Must be set to GDB_READER_INTERFACE_VERSION. */
int reader_version;
/* For use by the reader. */
void *priv_data;
gdb_read_debug_info *read;
gdb_unwind_frame *unwind;
gdb_get_frame_id *get_frame_id;
gdb_destroy_reader *destroy;
};
The callbacks are provided with another set of callbacks by GDB to
do their job. For `read', these callbacks are passed in a `struct
gdb_symbol_callbacks' and for `unwind' and `get_frame_id', in a `struct
gdb_unwind_callbacks'. `struct gdb_symbol_callbacks' has callbacks to
create new object files and new symbol tables inside those object
files. `struct gdb_unwind_callbacks' has callbacks to read registers
off the current frame and to write out the values of the registers in
the previous frame. Both have a callback (`target_read') to read bytes
off the target's address space.

File: gdb.info, Node: In-Process Agent, Next: GDB Bugs, Prev: JIT Interface, Up: Top
30 In-Process Agent
*******************
The traditional debugging model is conceptually low-speed, but works
fine, because most bugs can be reproduced in debugging-mode execution.
However, as multi-core or many-core processors are becoming mainstream,
and multi-threaded programs become more and more popular, there should
be more and more bugs that only manifest themselves at normal-mode
execution, for example, thread races, because debugger's interference
with the program's timing may conceal the bugs. On the other hand, in
some applications, it is not feasible for the debugger to interrupt the
program's execution long enough for the developer to learn anything
helpful about its behavior. If the program's correctness depends on
its real-time behavior, delays introduced by a debugger might cause the
program to fail, even when the code itself is correct. It is useful to
be able to observe the program's behavior without interrupting it.
Therefore, traditional debugging model is too intrusive to reproduce
some bugs. In order to reduce the interference with the program, we can
reduce the number of operations performed by debugger. The "In-Process
Agent", a shared library, is running within the same process with
inferior, and is able to perform some debugging operations itself. As
a result, debugger is only involved when necessary, and performance of
debugging can be improved accordingly. Note that interference with
program can be reduced but can't be removed completely, because the
in-process agent will still stop or slow down the program.
The in-process agent can interpret and execute Agent Expressions
(*note Agent Expressions::) during performing debugging operations. The
agent expressions can be used for different purposes, such as collecting
data in tracepoints, and condition evaluation in breakpoints.
You can control whether the in-process agent is used as an aid for
debugging with the following commands:
`set agent on'
Causes the in-process agent to perform some operations on behalf
of the debugger. Just which operations requested by the user will
be done by the in-process agent depends on the its capabilities.
For example, if you request to evaluate breakpoint conditions in
the in-process agent, and the in-process agent has such capability
as well, then breakpoint conditions will be evaluated in the
in-process agent.
`set agent off'
Disables execution of debugging operations by the in-process
agent. All of the operations will be performed by GDB.
`show agent'
Display the current setting of execution of debugging operations by
the in-process agent.
* Menu:
* In-Process Agent Protocol::

File: gdb.info, Node: In-Process Agent Protocol, Up: In-Process Agent
30.1 In-Process Agent Protocol
==============================
The in-process agent is able to communicate with both GDB and GDBserver
(*note In-Process Agent::). This section documents the protocol used
for communications between GDB or GDBserver and the IPA. In general,
GDB or GDBserver sends commands (*note IPA Protocol Commands::) and
data to in-process agent, and then in-process agent replies back with
the return result of the command, or some other information. The data
sent to in-process agent is composed of primitive data types, such as
4-byte or 8-byte type, and composite types, which are called objects
(*note IPA Protocol Objects::).
* Menu:
* IPA Protocol Objects::
* IPA Protocol Commands::

File: gdb.info, Node: IPA Protocol Objects, Next: IPA Protocol Commands, Up: In-Process Agent Protocol
30.1.1 IPA Protocol Objects
---------------------------
The commands sent to and results received from agent may contain some
complex data types called "objects".
The in-process agent is running on the same machine with GDB or
GDBserver, so it doesn't have to handle as much differences between two
ends as remote protocol (*note Remote Protocol::) tries to handle.
However, there are still some differences of two ends in two processes:
1. word size. On some 64-bit machines, GDB or GDBserver can be
compiled as a 64-bit executable, while in-process agent is a
32-bit one.
2. ABI. Some machines may have multiple types of ABI, GDB or
GDBserver is compiled with one, and in-process agent is compiled
with the other one.
Here are the IPA Protocol Objects:
1. agent expression object. It represents an agent expression (*note
Agent Expressions::).
2. tracepoint action object. It represents a tracepoint action
(*note Tracepoint Action Lists: Tracepoint Actions.) to collect
registers, memory, static trace data and to evaluate expression.
3. tracepoint object. It represents a tracepoint (*note
Tracepoints::).
The following table describes important attributes of each IPA
protocol object:
Name Size Description
---------------------------------------------------------------------------
_agent expression
object_
length 4 length of bytes code
byte code LENGTH contents of byte code
_tracepoint action
for collecting
memory_
'M' 1 type of tracepoint action
addr 8 if BASEREG is `-1', ADDR is the
address of the lowest byte to
collect, otherwise ADDR is the
offset of BASEREG for memory
collecting.
len 8 length of memory for collecting
basereg 4 the register number containing the
starting memory address for
collecting.
_tracepoint action
for collecting
registers_
'R' 1 type of tracepoint action
_tracepoint action
for collecting static
trace data_
'L' 1 type of tracepoint action
_tracepoint action
for expression
evaluation_
'X' 1 type of tracepoint action
agent expression length of *Note agent expression object::
_tracepoint object_
number 4 number of tracepoint
address 8 address of tracepoint inserted on
type 4 type of tracepoint
enabled 1 enable or disable of tracepoint
step_count 8 step
pass_count 8 pass
numactions 4 number of tracepoint actions
hit count 8 hit count
trace frame usage 8 trace frame usage
compiled_cond 8 compiled condition
orig_size 8 orig size
condition 4 if zero if condition is NULL,
condition is otherwise is *Note agent expression
NULL object::
otherwise
length of
*Note agent
expression
object::
actions variable numactions number of *Note
tracepoint action object::

File: gdb.info, Node: IPA Protocol Commands, Prev: IPA Protocol Objects, Up: In-Process Agent Protocol
30.1.2 IPA Protocol Commands
----------------------------
The spaces in each command are delimiters to ease reading this commands
specification. They don't exist in real commands.
`FastTrace:TRACEPOINT_OBJECT GDB_JUMP_PAD_HEAD'
Installs a new fast tracepoint described by TRACEPOINT_OBJECT
(*note tracepoint object::). GDB_JUMP_PAD_HEAD, 8-byte long, is
the head of "jumppad", which is used to jump to data collection
routine in IPA finally.
Replies:
`OK TARGET_ADDRESS GDB_JUMP_PAD_HEAD FJUMP_SIZE FJUMP'
TARGET_ADDRESS is address of tracepoint in the inferior.
GDB_JUMP_PAD_HEAD is updated head of jumppad. Both of
TARGET_ADDRESS and GDB_JUMP_PAD_HEAD are 8-byte long. FJUMP
contains a sequence of instructions jump to jumppad entry.
FJUMP_SIZE, 4-byte long, is the size of FJUMP.
`E NN'
for an error
`qTfSTM'
*Note qTfSTM::.
`qTsSTM'
*Note qTsSTM::.
`qTSTMat'
*Note qTSTMat::.
`probe_marker_at:ADDRESS'
Asks in-process agent to probe the marker at ADDRESS.
Replies:
`E NN'
for an error
`unprobe_marker_at:ADDRESS'
Asks in-process agent to unprobe the marker at ADDRESS.

File: gdb.info, Node: GDB Bugs, Next: Command Line Editing, Prev: In-Process Agent, Up: Top
31 Reporting Bugs in GDB
************************
Your bug reports play an essential role in making GDB reliable.
Reporting a bug may help you by bringing a solution to your problem,
or it may not. But in any case the principal function of a bug report
is to help the entire community by making the next version of GDB work
better. Bug reports are your contribution to the maintenance of GDB.
In order for a bug report to serve its purpose, you must include the
information that enables us to fix the bug.
* Menu:
* Bug Criteria:: Have you found a bug?
* Bug Reporting:: How to report bugs

File: gdb.info, Node: Bug Criteria, Next: Bug Reporting, Up: GDB Bugs
31.1 Have You Found a Bug?
==========================
If you are not sure whether you have found a bug, here are some
guidelines:
* If the debugger gets a fatal signal, for any input whatever, that
is a GDB bug. Reliable debuggers never crash.
* If GDB produces an error message for valid input, that is a bug.
(Note that if you're cross debugging, the problem may also be
somewhere in the connection to the target.)
* If GDB does not produce an error message for invalid input, that
is a bug. However, you should note that your idea of "invalid
input" might be our idea of "an extension" or "support for
traditional practice".
* If you are an experienced user of debugging tools, your suggestions
for improvement of GDB are welcome in any case.

File: gdb.info, Node: Bug Reporting, Prev: Bug Criteria, Up: GDB Bugs
31.2 How to Report Bugs
=======================
A number of companies and individuals offer support for GNU products.
If you obtained GDB from a support organization, we recommend you
contact that organization first.
You can find contact information for many support companies and
individuals in the file `etc/SERVICE' in the GNU Emacs distribution.
In any event, we also recommend that you submit bug reports for GDB.
The preferred method is to submit them directly using GDB's Bugs web
page (http://www.gnu.org/software/gdb/bugs/). Alternatively, the
e-mail gateway <bug-gdb@gnu.org> can be used.
*Do not send bug reports to `info-gdb', or to `help-gdb', or to any
newsgroups.* Most users of GDB do not want to receive bug reports.
Those that do have arranged to receive `bug-gdb'.
The mailing list `bug-gdb' has a newsgroup `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.
The fundamental principle of reporting bugs usefully is this:
*report all the facts*. If you are not sure whether to state a 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 do not matter. Thus, you might
assume that the name of the variable you use in an example does not
matter. 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 the bug. Play it safe and give a
specific, complete example. That is the 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. It may be that the bug has been reported previously, but
neither you nor we can know that unless your bug report is complete and
self-contained.
Sometimes people give a few sketchy facts and ask, "Does this ring a
bell?" Those bug reports are useless, and we urge everyone to _refuse
to respond to them_ except to chide the sender to report bugs properly.
To enable us to fix the bug, you should include all these things:
* The version of GDB. GDB announces it if you start with no
arguments; you can also print it at any time using `show version'.
Without this, we will not know whether there is any point in
looking for the bug in the current version of GDB.
* The type of machine you are using, and the operating system name
and version number.
* What compiler (and its version) was used to compile GDB--e.g.
"gcc-2.8.1".
* What compiler (and its version) was used to compile the program
you are debugging--e.g. "gcc-2.8.1", or "HP92453-01 A.10.32.03 HP
C Compiler". For GCC, you can say `gcc --version' to get this
information; for other compilers, see the documentation for those
compilers.
* The command arguments you gave the compiler to compile your
example and observe the bug. For example, did you use `-O'? To
guarantee 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.
* A complete input script, and all necessary source files, that will
reproduce the bug.
* A description of what behavior you observe that you believe is
incorrect. For example, "It gets a fatal signal."
Of course, if the bug is that GDB gets a fatal signal, then we
will certainly notice it. But if the bug is incorrect output, we
might not notice unless it is glaringly wrong. You might as well
not give us a chance to make a mistake.
Even if the problem you experience is a fatal signal, you should
still say so explicitly. Suppose something strange is going on,
such as, your copy of GDB is out of synch, or you have encountered
a bug in the C library on your system. (This has happened!) Your
copy might crash and ours would not. If you told us to expect a
crash, then when ours fails to crash, we would know that the bug
was not happening for us. If you had not told us to expect a
crash, then we would not be able to draw any conclusion from our
observations.
To collect all this information, you can use a session recording
program such as `script', which is available on many Unix systems.
Just run your GDB session inside `script' and then include the
`typescript' file with your bug report.
Another way to record a GDB session is to run GDB inside Emacs and
then save the entire buffer to a file.
* If you wish to suggest changes to the GDB source, send us context
diffs. If you even discuss something in the GDB source, refer to
it by context, not by line number.
The line numbers in our development sources will not match those
in your sources. Your line numbers would convey no useful
information to us.
Here are some things that are not necessary:
* A description of the envelope of the bug.
Often people who encounter a bug spend a lot of time investigating
which changes to the input file will make the bug go away and which
changes will not affect it.
This is often time consuming and not very useful, because the way
we will find the bug is by running a single example under the
debugger with breakpoints, not by pure deduction from a series of
examples. We recommend that you save your time for something else.
Of course, if you can find a simpler example to report _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, and so on.
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.
* A patch for the bug.
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 GDB it is very hard to
construct an example that will make the program follow a certain
path 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 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.
* A guess about what the bug is or what it depends on.
Such guesses are usually wrong. Even we cannot guess right about
such things without first using the debugger to find the facts.

File: gdb.info, Node: Command Line Editing, Next: Using History Interactively, Prev: GDB Bugs, Up: Top
32 Command Line Editing
***********************
This chapter describes the basic features of the GNU command line
editing interface.
* Menu:
* Introduction and Notation:: Notation used in this text.
* Readline Interaction:: The minimum set of commands for editing a line.
* Readline Init File:: Customizing Readline from a user's view.
* Bindable Readline Commands:: A description of most of the Readline commands
available for binding
* Readline vi Mode:: A short description of how to make Readline
behave like the vi editor.

File: gdb.info, Node: Introduction and Notation, Next: Readline Interaction, Up: Command Line Editing
32.1 Introduction to Line Editing
=================================
The following paragraphs describe the notation used to represent
keystrokes.
The text `C-k' is read as `Control-K' and describes the character
produced when the <k> key is pressed while the Control key is depressed.
The text `M-k' is read as `Meta-K' and describes the character
produced when the Meta key (if you have one) is depressed, and the <k>
key is pressed. The Meta key is labeled <ALT> on many keyboards. On
keyboards with two keys labeled <ALT> (usually to either side of the
space bar), the <ALT> on the left side is generally set to work as a
Meta key. The <ALT> key on the right may also be configured to work as
a Meta key or may be configured as some other modifier, such as a
Compose key for typing accented characters.
If you do not have a Meta or <ALT> key, or another key working as a
Meta key, the identical keystroke can be generated by typing <ESC>
_first_, and then typing <k>. Either process is known as "metafying"
the <k> key.
The text `M-C-k' is read as `Meta-Control-k' and describes the
character produced by "metafying" `C-k'.
In addition, several keys have their own names. Specifically,
<DEL>, <ESC>, <LFD>, <SPC>, <RET>, and <TAB> all stand for themselves
when seen in this text, or in an init file (*note Readline Init File::).
If your keyboard lacks a <LFD> key, typing <C-j> will produce the
desired character. The <RET> key may be labeled <Return> or <Enter> on
some keyboards.

File: gdb.info, Node: Readline Interaction, Next: Readline Init File, Prev: Introduction and Notation, Up: Command Line Editing
32.2 Readline Interaction
=========================
Often during an interactive session you type in a long line of text,
only to notice that the first word on the line is misspelled. The
Readline library gives you a set of commands for manipulating the text
as you type it in, allowing you to just fix your typo, and not forcing
you to retype the majority of the line. Using these editing commands,
you move the cursor to the place that needs correction, and delete or
insert the text of the corrections. Then, when you are satisfied with
the line, you simply press <RET>. You do not have to be at the end of
the line to press <RET>; the entire line is accepted regardless of the
location of the cursor within the line.
* Menu:
* Readline Bare Essentials:: The least you need to know about Readline.
* Readline Movement Commands:: Moving about the input line.
* Readline Killing Commands:: How to delete text, and how to get it back!
* Readline Arguments:: Giving numeric arguments to commands.
* Searching:: Searching through previous lines.

File: gdb.info, Node: Readline Bare Essentials, Next: Readline Movement Commands, Up: Readline Interaction
32.2.1 Readline Bare Essentials
-------------------------------
In order to enter characters into the line, simply type them. The typed
character appears where the cursor was, and then the cursor moves one
space to the right. If you mistype a character, you can use your erase
character to back up and delete the mistyped character.
Sometimes you may mistype a character, and not notice the error
until you have typed several other characters. In that case, you can
type `C-b' to move the cursor to the left, and then correct your
mistake. Afterwards, you can move the cursor to the right with `C-f'.
When you add text in the middle of a line, you will notice that
characters to the right of the cursor are `pushed over' to make room
for the text that you have inserted. Likewise, when you delete text
behind the cursor, characters to the right of the cursor are `pulled
back' to fill in the blank space created by the removal of the text. A
list of the bare essentials for editing the text of an input line
follows.
`C-b'
Move back one character.
`C-f'
Move forward one character.
<DEL> or <Backspace>
Delete the character to the left of the cursor.
`C-d'
Delete the character underneath the cursor.
Printing characters
Insert the character into the line at the cursor.
`C-_' or `C-x C-u'
Undo the last editing command. You can undo all the way back to an
empty line.
(Depending on your configuration, the <Backspace> key be set to delete
the character to the left of the cursor and the <DEL> key set to delete
the character underneath the cursor, like `C-d', rather than the
character to the left of the cursor.)

File: gdb.info, Node: Readline Movement Commands, Next: Readline Killing Commands, Prev: Readline Bare Essentials, Up: Readline Interaction
32.2.2 Readline Movement Commands
---------------------------------
The above table describes the most basic keystrokes that you need in
order to do editing of the input line. For your convenience, many
other commands have been added in addition to `C-b', `C-f', `C-d', and
<DEL>. Here are some commands for moving more rapidly about the line.
`C-a'
Move to the start of the line.
`C-e'
Move to the end of the line.
`M-f'
Move forward a word, where a word is composed of letters and
digits.
`M-b'
Move backward a word.
`C-l'
Clear the screen, reprinting the current line at the top.
Notice how `C-f' moves forward a character, while `M-f' moves
forward a word. It is a loose convention that control keystrokes
operate on characters while meta keystrokes operate on words.

File: gdb.info, Node: Readline Killing Commands, Next: Readline Arguments, Prev: Readline Movement Commands, Up: Readline Interaction
32.2.3 Readline Killing Commands
--------------------------------
"Killing" text means to delete the text from the line, but to save it
away for later use, usually by "yanking" (re-inserting) it back into
the line. (`Cut' and `paste' are more recent jargon for `kill' and
`yank'.)
If the description for a command says that it `kills' text, then you
can be sure that you can get the text back in a different (or the same)
place later.
When you use a kill command, the text is saved in a "kill-ring".
Any number of consecutive kills save all of the killed text together, so
that when you yank it back, you get it all. The kill ring is not line
specific; the text that you killed on a previously typed line is
available to be yanked back later, when you are typing another line.
Here is the list of commands for killing text.
`C-k'
Kill the text from the current cursor position to the end of the
line.
`M-d'
Kill from the cursor to the end of the current word, or, if between
words, to the end of the next word. Word boundaries are the same
as those used by `M-f'.
`M-<DEL>'
Kill from the cursor the start of the current word, or, if between
words, to the start of the previous word. Word boundaries are the
same as those used by `M-b'.
`C-w'
Kill from the cursor to the previous whitespace. This is
different than `M-<DEL>' because the word boundaries differ.
Here is how to "yank" the text back into the line. Yanking means to
copy the most-recently-killed text from the kill buffer.
`C-y'
Yank the most recently killed text back into the buffer at the
cursor.
`M-y'
Rotate the kill-ring, and yank the new top. You can only do this
if the prior command is `C-y' or `M-y'.

File: gdb.info, Node: Readline Arguments, Next: Searching, Prev: Readline Killing Commands, Up: Readline Interaction
32.2.4 Readline Arguments
-------------------------
You can pass numeric arguments to Readline commands. Sometimes the
argument acts as a repeat count, other times it is the sign of the
argument that is significant. If you pass a negative argument to a
command which normally acts in a forward direction, that command will
act in a backward direction. For example, to kill text back to the
start of the line, you might type `M-- C-k'.
The general way to pass numeric arguments to a command is to type
meta digits before the command. If the first `digit' typed is a minus
sign (`-'), then the sign of the argument will be negative. Once you
have typed one meta digit to get the argument started, you can type the
remainder of the digits, and then the command. For example, to give
the `C-d' command an argument of 10, you could type `M-1 0 C-d', which
will delete the next ten characters on the input line.

File: gdb.info, Node: Searching, Prev: Readline Arguments, Up: Readline Interaction
32.2.5 Searching for Commands in the History
--------------------------------------------
Readline provides commands for searching through the command history
for lines containing a specified string. There are two search modes:
"incremental" and "non-incremental".
Incremental searches begin before the user has finished typing the
search string. As each character of the search string is typed,
Readline displays the next entry from the history matching the string
typed so far. An incremental search requires only as many characters
as needed to find the desired history entry. To search backward in the
history for a particular string, type `C-r'. Typing `C-s' searches
forward through the history. The characters present in the value of
the `isearch-terminators' variable are used to terminate an incremental
search. If that variable has not been assigned a value, the <ESC> and
`C-J' characters will terminate an incremental search. `C-g' will
abort an incremental search and restore the original line. When the
search is terminated, the history entry containing the search string
becomes the current line.
To find other matching entries in the history list, type `C-r' or
`C-s' as appropriate. This will search backward or forward in the
history for the next entry matching the search string typed so far.
Any other key sequence bound to a Readline command will terminate the
search and execute that command. For instance, a <RET> will terminate
the search and accept the line, thereby executing the command from the
history list. A movement command will terminate the search, make the
last line found the current line, and begin editing.
Readline remembers the last incremental search string. If two
`C-r's are typed without any intervening characters defining a new
search string, any remembered search string is used.
Non-incremental searches read the entire search string before
starting to search for matching history lines. The search string may be
typed by the user or be part of the contents of the current line.

File: gdb.info, Node: Readline Init File, Next: Bindable Readline Commands, Prev: Readline Interaction, Up: Command Line Editing
32.3 Readline Init File
=======================
Although the Readline library comes with a set of Emacs-like
keybindings installed by default, it is possible to use a different set
of keybindings. Any user can customize programs that use Readline by
putting commands in an "inputrc" file, conventionally in his home
directory. The name of this file is taken from the value of the
environment variable `INPUTRC'. If that variable is unset, the default
is `~/.inputrc'. If that file does not exist or cannot be read, the
ultimate default is `/etc/inputrc'.
When a program which uses the Readline library starts up, the init
file is read, and the key bindings are set.
In addition, the `C-x C-r' command re-reads this init file, thus
incorporating any changes that you might have made to it.
* Menu:
* Readline Init File Syntax:: Syntax for the commands in the inputrc file.
* Conditional Init Constructs:: Conditional key bindings in the inputrc file.
* Sample Init File:: An example inputrc file.

File: gdb.info, Node: Readline Init File Syntax, Next: Conditional Init Constructs, Up: Readline Init File
32.3.1 Readline Init File Syntax
--------------------------------
There are only a few basic constructs allowed in the Readline init
file. Blank lines are ignored. Lines beginning with a `#' are
comments. Lines beginning with a `$' indicate conditional constructs
(*note Conditional Init Constructs::). Other lines denote variable
settings and key bindings.
Variable Settings
You can modify the run-time behavior of Readline by altering the
values of variables in Readline using the `set' command within the
init file. The syntax is simple:
set VARIABLE VALUE
Here, for example, is how to change from the default Emacs-like
key binding to use `vi' line editing commands:
set editing-mode vi
Variable names and values, where appropriate, are recognized
without regard to case. Unrecognized variable names are ignored.
Boolean variables (those that can be set to on or off) are set to
on if the value is null or empty, ON (case-insensitive), or 1.
Any other value results in the variable being set to off.
A great deal of run-time behavior is changeable with the following
variables.
`bell-style'
Controls what happens when Readline wants to ring the
terminal bell. If set to `none', Readline never rings the
bell. If set to `visible', Readline uses a visible bell if
one is available. If set to `audible' (the default),
Readline attempts to ring the terminal's bell.
`bind-tty-special-chars'
If set to `on', Readline attempts to bind the control
characters treated specially by the kernel's terminal driver
to their Readline equivalents.
`comment-begin'
The string to insert at the beginning of the line when the
`insert-comment' command is executed. The default value is
`"#"'.
`completion-display-width'
The number of screen columns used to display possible matches
when performing completion. The value is ignored if it is
less than 0 or greater than the terminal screen width. A
value of 0 will cause matches to be displayed one per line.
The default value is -1.
`completion-ignore-case'
If set to `on', Readline performs filename matching and
completion in a case-insensitive fashion. The default value
is `off'.
`completion-map-case'
If set to `on', and COMPLETION-IGNORE-CASE is enabled,
Readline treats hyphens (`-') and underscores (`_') as
equivalent when performing case-insensitive filename matching
and completion.
`completion-prefix-display-length'
The length in characters of the common prefix of a list of
possible completions that is displayed without modification.
When set to a value greater than zero, common prefixes longer
than this value are replaced with an ellipsis when displaying
possible completions.
`completion-query-items'
The number of possible completions that determines when the
user is asked whether the list of possibilities should be
displayed. If the number of possible completions is greater
than this value, Readline will ask the user whether or not he
wishes to view them; otherwise, they are simply listed. This
variable must be set to an integer value greater than or
equal to 0. A negative value means Readline should never ask.
The default limit is `100'.
`convert-meta'
If set to `on', Readline will convert characters with the
eighth bit set to an ASCII key sequence by stripping the
eighth bit and prefixing an <ESC> character, converting them
to a meta-prefixed key sequence. The default value is `on'.
`disable-completion'
If set to `On', Readline will inhibit word completion.
Completion characters will be inserted into the line as if
they had been mapped to `self-insert'. The default is `off'.
`editing-mode'
The `editing-mode' variable controls which default set of key
bindings is used. By default, Readline starts up in Emacs
editing mode, where the keystrokes are most similar to Emacs.
This variable can be set to either `emacs' or `vi'.
`echo-control-characters'
When set to `on', on operating systems that indicate they
support it, readline echoes a character corresponding to a
signal generated from the keyboard. The default is `on'.
`enable-keypad'
When set to `on', Readline will try to enable the application
keypad when it is called. Some systems need this to enable
the arrow keys. The default is `off'.
`enable-meta-key'
When set to `on', Readline will try to enable any meta
modifier key the terminal claims to support when it is
called. On many terminals, the meta key is used to send
eight-bit characters. The default is `on'.
`expand-tilde'
If set to `on', tilde expansion is performed when Readline
attempts word completion. The default is `off'.
`history-preserve-point'
If set to `on', the history code attempts to place the point
(the current cursor position) at the same location on each
history line retrieved with `previous-history' or
`next-history'. The default is `off'.
`history-size'
Set the maximum number of history entries saved in the
history list. If set to zero, the number of entries in the
history list is not limited.
`horizontal-scroll-mode'
This variable can be set to either `on' or `off'. Setting it
to `on' means that the text of the lines being edited will
scroll horizontally on a single screen line when they are
longer than the width of the screen, instead of wrapping onto
a new screen line. By default, this variable is set to `off'.
`input-meta'
If set to `on', Readline will enable eight-bit input (it will
not clear the eighth bit in the characters it reads),
regardless of what the terminal claims it can support. The
default value is `off'. The name `meta-flag' is a synonym
for this variable.
`isearch-terminators'
The string of characters that should terminate an incremental
search without subsequently executing the character as a
command (*note Searching::). If this variable has not been
given a value, the characters <ESC> and `C-J' will terminate
an incremental search.
`keymap'
Sets Readline's idea of the current keymap for key binding
commands. Acceptable `keymap' names are `emacs',
`emacs-standard', `emacs-meta', `emacs-ctlx', `vi', `vi-move',
`vi-command', and `vi-insert'. `vi' is equivalent to
`vi-command'; `emacs' is equivalent to `emacs-standard'. The
default value is `emacs'. The value of the `editing-mode'
variable also affects the default keymap.
`mark-directories'
If set to `on', completed directory names have a slash
appended. The default is `on'.
`mark-modified-lines'
This variable, when set to `on', causes Readline to display an
asterisk (`*') at the start of history lines which have been
modified. This variable is `off' by default.
`mark-symlinked-directories'
If set to `on', completed names which are symbolic links to
directories have a slash appended (subject to the value of
`mark-directories'). The default is `off'.
`match-hidden-files'
This variable, when set to `on', causes Readline to match
files whose names begin with a `.' (hidden files) when
performing filename completion. If set to `off', the leading
`.' must be supplied by the user in the filename to be
completed. This variable is `on' by default.
`menu-complete-display-prefix'
If set to `on', menu completion displays the common prefix of
the list of possible completions (which may be empty) before
cycling through the list. The default is `off'.
`output-meta'
If set to `on', Readline will display characters with the
eighth bit set directly rather than as a meta-prefixed escape
sequence. The default is `off'.
`page-completions'
If set to `on', Readline uses an internal `more'-like pager
to display a screenful of possible completions at a time.
This variable is `on' by default.
`print-completions-horizontally'
If set to `on', Readline will display completions with matches
sorted horizontally in alphabetical order, rather than down
the screen. The default is `off'.
`revert-all-at-newline'
If set to `on', Readline will undo all changes to history
lines before returning when `accept-line' is executed. By
default, history lines may be modified and retain individual
undo lists across calls to `readline'. The default is `off'.
`show-all-if-ambiguous'
This alters the default behavior of the completion functions.
If set to `on', words which have more than one possible
completion cause the matches to be listed immediately instead
of ringing the bell. The default value is `off'.
`show-all-if-unmodified'
This alters the default behavior of the completion functions
in a fashion similar to SHOW-ALL-IF-AMBIGUOUS. If set to
`on', words which have more than one possible completion
without any possible partial completion (the possible
completions don't share a common prefix) cause the matches to
be listed immediately instead of ringing the bell. The
default value is `off'.
`skip-completed-text'
If set to `on', this alters the default completion behavior
when inserting a single match into the line. It's only
active when performing completion in the middle of a word.
If enabled, readline does not insert characters from the
completion that match characters after point in the word
being completed, so portions of the word following the cursor
are not duplicated. For instance, if this is enabled,
attempting completion when the cursor is after the `e' in
`Makefile' will result in `Makefile' rather than
`Makefilefile', assuming there is a single possible
completion. The default value is `off'.
`visible-stats'
If set to `on', a character denoting a file's type is
appended to the filename when listing possible completions.
The default is `off'.
Key Bindings
The syntax for controlling key bindings in the init file is
simple. First you need to find the name of the command that you
want to change. The following sections contain tables of the
command name, the default keybinding, if any, and a short
description of what the command does.
Once you know the name of the command, simply place on a line in
the init file the name of the key you wish to bind the command to,
a colon, and then the name of the command. There can be no space
between the key name and the colon - that will be interpreted as
part of the key name. The name of the key can be expressed in
different ways, depending on what you find most comfortable.
In addition to command names, readline allows keys to be bound to
a string that is inserted when the key is pressed (a MACRO).
KEYNAME: FUNCTION-NAME or MACRO
KEYNAME is the name of a key spelled out in English. For
example:
Control-u: universal-argument
Meta-Rubout: backward-kill-word
Control-o: "> output"
In the above example, `C-u' is bound to the function
`universal-argument', `M-DEL' is bound to the function
`backward-kill-word', and `C-o' is bound to run the macro
expressed on the right hand side (that is, to insert the text
`> output' into the line).
A number of symbolic character names are recognized while
processing this key binding syntax: DEL, ESC, ESCAPE, LFD,
NEWLINE, RET, RETURN, RUBOUT, SPACE, SPC, and TAB.
"KEYSEQ": FUNCTION-NAME or MACRO
KEYSEQ differs from KEYNAME above in that strings denoting an
entire key sequence can be specified, by placing the key
sequence in double quotes. Some GNU Emacs style key escapes
can be used, as in the following example, but the special
character names are not recognized.
"\C-u": universal-argument
"\C-x\C-r": re-read-init-file
"\e[11~": "Function Key 1"
In the above example, `C-u' is again bound to the function
`universal-argument' (just as it was in the first example),
`C-x C-r' is bound to the function `re-read-init-file', and
`<ESC> <[> <1> <1> <~>' is bound to insert the text `Function
Key 1'.
The following GNU Emacs style escape sequences are available when
specifying key sequences:
`\C-'
control prefix
`\M-'
meta prefix
`\e'
an escape character
`\\'
backslash
`\"'
<">, a double quotation mark
`\''
<'>, a single quote or apostrophe
In addition to the GNU Emacs style escape sequences, a second set
of backslash escapes is available:
`\a'
alert (bell)
`\b'
backspace
`\d'
delete
`\f'
form feed
`\n'
newline
`\r'
carriage return
`\t'
horizontal tab
`\v'
vertical tab
`\NNN'
the eight-bit character whose value is the octal value NNN
(one to three digits)
`\xHH'
the eight-bit character whose value is the hexadecimal value
HH (one or two hex digits)
When entering the text of a macro, single or double quotes must be
used to indicate a macro definition. Unquoted text is assumed to
be a function name. In the macro body, the backslash escapes
described above are expanded. Backslash will quote any other
character in the macro text, including `"' and `''. For example,
the following binding will make `C-x \' insert a single `\' into
the line:
"\C-x\\": "\\"

File: gdb.info, Node: Conditional Init Constructs, Next: Sample Init File, Prev: Readline Init File Syntax, Up: Readline Init File
32.3.2 Conditional Init Constructs
----------------------------------
Readline implements a facility similar in spirit to the conditional
compilation features of the C preprocessor which allows key bindings
and variable settings to be performed as the result of tests. There
are four parser directives used.
`$if'
The `$if' construct allows bindings to be made based on the
editing mode, the terminal being used, or the application using
Readline. The text of the test extends to the end of the line; no
characters are required to isolate it.
`mode'
The `mode=' form of the `$if' directive is used to test
whether Readline is in `emacs' or `vi' mode. This may be
used in conjunction with the `set keymap' command, for
instance, to set bindings in the `emacs-standard' and
`emacs-ctlx' keymaps only if Readline is starting out in
`emacs' mode.
`term'
The `term=' form may be used to include terminal-specific key
bindings, perhaps to bind the key sequences output by the
terminal's function keys. The word on the right side of the
`=' is tested against both the full name of the terminal and
the portion of the terminal name before the first `-'. This
allows `sun' to match both `sun' and `sun-cmd', for instance.
`application'
The APPLICATION construct is used to include
application-specific settings. Each program using the
Readline library sets the APPLICATION NAME, and you can test
for a particular value. This could be used to bind key
sequences to functions useful for a specific program. For
instance, the following command adds a key sequence that
quotes the current or previous word in Bash:
$if Bash
# Quote the current or previous word
"\C-xq": "\eb\"\ef\""
$endif
`$endif'
This command, as seen in the previous example, terminates an `$if'
command.
`$else'
Commands in this branch of the `$if' directive are executed if the
test fails.
`$include'
This directive takes a single filename as an argument and reads
commands and bindings from that file. For example, the following
directive reads from `/etc/inputrc':
$include /etc/inputrc

File: gdb.info, Node: Sample Init File, Prev: Conditional Init Constructs, Up: Readline Init File
32.3.3 Sample Init File
-----------------------
Here is an example of an INPUTRC file. This illustrates key binding,
variable assignment, and conditional syntax.
# This file controls the behaviour of line input editing for
# programs that use the GNU Readline library. Existing
# programs include FTP, Bash, and GDB.
#
# You can re-read the inputrc file with C-x C-r.
# Lines beginning with '#' are comments.
#
# First, include any systemwide bindings and variable
# assignments from /etc/Inputrc
$include /etc/Inputrc
#
# Set various bindings for emacs mode.
set editing-mode emacs
$if mode=emacs
Meta-Control-h: backward-kill-word Text after the function name is ignored
#
# Arrow keys in keypad mode
#
#"\M-OD": backward-char
#"\M-OC": forward-char
#"\M-OA": previous-history
#"\M-OB": next-history
#
# Arrow keys in ANSI mode
#
"\M-[D": backward-char
"\M-[C": forward-char
"\M-[A": previous-history
"\M-[B": next-history
#
# Arrow keys in 8 bit keypad mode
#
#"\M-\C-OD": backward-char
#"\M-\C-OC": forward-char
#"\M-\C-OA": previous-history
#"\M-\C-OB": next-history
#
# Arrow keys in 8 bit ANSI mode
#
#"\M-\C-[D": backward-char
#"\M-\C-[C": forward-char
#"\M-\C-[A": previous-history
#"\M-\C-[B": next-history
C-q: quoted-insert
$endif
# An old-style binding. This happens to be the default.
TAB: complete
# Macros that are convenient for shell interaction
$if Bash
# edit the path
"\C-xp": "PATH=${PATH}\e\C-e\C-a\ef\C-f"
# prepare to type a quoted word --
# insert open and close double quotes
# and move to just after the open quote
"\C-x\"": "\"\"\C-b"
# insert a backslash (testing backslash escapes
# in sequences and macros)
"\C-x\\": "\\"
# Quote the current or previous word
"\C-xq": "\eb\"\ef\""
# Add a binding to refresh the line, which is unbound
"\C-xr": redraw-current-line
# Edit variable on current line.
"\M-\C-v": "\C-a\C-k$\C-y\M-\C-e\C-a\C-y="
$endif
# use a visible bell if one is available
set bell-style visible
# don't strip characters to 7 bits when reading
set input-meta on
# allow iso-latin1 characters to be inserted rather
# than converted to prefix-meta sequences
set convert-meta off
# display characters with the eighth bit set directly
# rather than as meta-prefixed characters
set output-meta on
# if there are more than 150 possible completions for
# a word, ask the user if he wants to see all of them
set completion-query-items 150
# For FTP
$if Ftp
"\C-xg": "get \M-?"
"\C-xt": "put \M-?"
"\M-.": yank-last-arg
$endif

File: gdb.info, Node: Bindable Readline Commands, Next: Readline vi Mode, Prev: Readline Init File, Up: Command Line Editing
32.4 Bindable Readline Commands
===============================
* Menu:
* Commands For Moving:: Moving about the line.
* Commands For History:: Getting at previous lines.
* Commands For Text:: Commands for changing text.
* Commands For Killing:: Commands for killing and yanking.
* Numeric Arguments:: Specifying numeric arguments, repeat counts.
* Commands For Completion:: Getting Readline to do the typing for you.
* Keyboard Macros:: Saving and re-executing typed characters
* Miscellaneous Commands:: Other miscellaneous commands.
This section describes Readline commands that may be bound to key
sequences. Command names without an accompanying key sequence are
unbound by default.
In the following descriptions, "point" refers to the current cursor
position, and "mark" refers to a cursor position saved by the
`set-mark' command. The text between the point and mark is referred to
as the "region".

File: gdb.info, Node: Commands For Moving, Next: Commands For History, Up: Bindable Readline Commands
32.4.1 Commands For Moving
--------------------------
`beginning-of-line (C-a)'
Move to the start of the current line.
`end-of-line (C-e)'
Move to the end of the line.
`forward-char (C-f)'
Move forward a character.
`backward-char (C-b)'
Move back a character.
`forward-word (M-f)'
Move forward to the end of the next word. Words are composed of
letters and digits.
`backward-word (M-b)'
Move back to the start of the current or previous word. Words are
composed of letters and digits.
`clear-screen (C-l)'
Clear the screen and redraw the current line, leaving the current
line at the top of the screen.
`redraw-current-line ()'
Refresh the current line. By default, this is unbound.

File: gdb.info, Node: Commands For History, Next: Commands For Text, Prev: Commands For Moving, Up: Bindable Readline Commands
32.4.2 Commands For Manipulating The History
--------------------------------------------
`accept-line (Newline or Return)'
Accept the line regardless of where the cursor is. If this line is
non-empty, it may be added to the history list for future recall
with `add_history()'. If this line is a modified history line,
the history line is restored to its original state.
`previous-history (C-p)'
Move `back' through the history list, fetching the previous
command.
`next-history (C-n)'
Move `forward' through the history list, fetching the next command.
`beginning-of-history (M-<)'
Move to the first line in the history.
`end-of-history (M->)'
Move to the end of the input history, i.e., the line currently
being entered.
`reverse-search-history (C-r)'
Search backward starting at the current line and moving `up'
through the history as necessary. This is an incremental search.
`forward-search-history (C-s)'
Search forward starting at the current line and moving `down'
through the the history as necessary. This is an incremental
search.
`non-incremental-reverse-search-history (M-p)'
Search backward starting at the current line and moving `up'
through the history as necessary using a non-incremental search
for a string supplied by the user.
`non-incremental-forward-search-history (M-n)'
Search forward starting at the current line and moving `down'
through the the history as necessary using a non-incremental search
for a string supplied by the user.
`history-search-forward ()'
Search forward through the history for the string of characters
between the start of the current line and the point. This is a
non-incremental search. By default, this command is unbound.
`history-search-backward ()'
Search backward through the history for the string of characters
between the start of the current line and the point. This is a
non-incremental search. By default, this command is unbound.
`yank-nth-arg (M-C-y)'
Insert the first argument to the previous command (usually the
second word on the previous line) at point. With an argument N,
insert the Nth word from the previous command (the words in the
previous command begin with word 0). A negative argument inserts
the Nth word from the end of the previous command. Once the
argument N is computed, the argument is extracted as if the `!N'
history expansion had been specified.
`yank-last-arg (M-. or M-_)'
Insert last argument to the previous command (the last word of the
previous history entry). With a numeric argument, behave exactly
like `yank-nth-arg'. Successive calls to `yank-last-arg' move
back through the history list, inserting the last word (or the
word specified by the argument to the first call) of each line in
turn. Any numeric argument supplied to these successive calls
determines the direction to move through the history. A negative
argument switches the direction through the history (back or
forward). The history expansion facilities are used to extract
the last argument, as if the `!$' history expansion had been
specified.

File: gdb.info, Node: Commands For Text, Next: Commands For Killing, Prev: Commands For History, Up: Bindable Readline Commands
32.4.3 Commands For Changing Text
---------------------------------
`delete-char (C-d)'
Delete the character at point. If point is at the beginning of
the line, there are no characters in the line, and the last
character typed was not bound to `delete-char', then return EOF.
`backward-delete-char (Rubout)'
Delete the character behind the cursor. A numeric argument means
to kill the characters instead of deleting them.
`forward-backward-delete-char ()'
Delete the character under the cursor, unless the cursor is at the
end of the line, in which case the character behind the cursor is
deleted. By default, this is not bound to a key.
`quoted-insert (C-q or C-v)'
Add the next character typed to the line verbatim. This is how to
insert key sequences like `C-q', for example.
`tab-insert (M-<TAB>)'
Insert a tab character.
`self-insert (a, b, A, 1, !, ...)'
Insert yourself.
`transpose-chars (C-t)'
Drag the character before the cursor forward over the character at
the cursor, moving the cursor forward as well. If the insertion
point is at the end of the line, then this transposes the last two
characters of the line. Negative arguments have no effect.
`transpose-words (M-t)'
Drag the word before point past the word after point, moving point
past that word as well. If the insertion point is at the end of
the line, this transposes the last two words on the line.
`upcase-word (M-u)'
Uppercase the current (or following) word. With a negative
argument, uppercase the previous word, but do not move the cursor.
`downcase-word (M-l)'
Lowercase the current (or following) word. With a negative
argument, lowercase the previous word, but do not move the cursor.
`capitalize-word (M-c)'
Capitalize the current (or following) word. With a negative
argument, capitalize the previous word, but do not move the cursor.
`overwrite-mode ()'
Toggle overwrite mode. With an explicit positive numeric argument,
switches to overwrite mode. With an explicit non-positive numeric
argument, switches to insert mode. This command affects only
`emacs' mode; `vi' mode does overwrite differently. Each call to
`readline()' starts in insert mode.
In overwrite mode, characters bound to `self-insert' replace the
text at point rather than pushing the text to the right.
Characters bound to `backward-delete-char' replace the character
before point with a space.
By default, this command is unbound.

File: gdb.info, Node: Commands For Killing, Next: Numeric Arguments, Prev: Commands For Text, Up: Bindable Readline Commands
32.4.4 Killing And Yanking
--------------------------
`kill-line (C-k)'
Kill the text from point to the end of the line.
`backward-kill-line (C-x Rubout)'
Kill backward to the beginning of the line.
`unix-line-discard (C-u)'
Kill backward from the cursor to the beginning of the current line.
`kill-whole-line ()'
Kill all characters on the current line, no matter where point is.
By default, this is unbound.
`kill-word (M-d)'
Kill from point to the end of the current word, or if between
words, to the end of the next word. Word boundaries are the same
as `forward-word'.
`backward-kill-word (M-<DEL>)'
Kill the word behind point. Word boundaries are the same as
`backward-word'.
`unix-word-rubout (C-w)'
Kill the word behind point, using white space as a word boundary.
The killed text is saved on the kill-ring.
`unix-filename-rubout ()'
Kill the word behind point, using white space and the slash
character as the word boundaries. The killed text is saved on the
kill-ring.
`delete-horizontal-space ()'
Delete all spaces and tabs around point. By default, this is
unbound.
`kill-region ()'
Kill the text in the current region. By default, this command is
unbound.
`copy-region-as-kill ()'
Copy the text in the region to the kill buffer, so it can be yanked
right away. By default, this command is unbound.
`copy-backward-word ()'
Copy the word before point to the kill buffer. The word
boundaries are the same as `backward-word'. By default, this
command is unbound.
`copy-forward-word ()'
Copy the word following point to the kill buffer. The word
boundaries are the same as `forward-word'. By default, this
command is unbound.
`yank (C-y)'
Yank the top of the kill ring into the buffer at point.
`yank-pop (M-y)'
Rotate the kill-ring, and yank the new top. You can only do this
if the prior command is `yank' or `yank-pop'.

File: gdb.info, Node: Numeric Arguments, Next: Commands For Completion, Prev: Commands For Killing, Up: Bindable Readline Commands
32.4.5 Specifying Numeric Arguments
-----------------------------------
`digit-argument (M-0, M-1, ... M--)'
Add this digit to the argument already accumulating, or start a new
argument. `M--' starts a negative argument.
`universal-argument ()'
This is another way to specify an argument. If this command is
followed by one or more digits, optionally with a leading minus
sign, those digits define the argument. If the command is
followed by digits, executing `universal-argument' again ends the
numeric argument, but is otherwise ignored. As a special case, if
this command is immediately followed by a character that is
neither a digit or minus sign, the argument count for the next
command is multiplied by four. The argument count is initially
one, so executing this function the first time makes the argument
count four, a second time makes the argument count sixteen, and so
on. By default, this is not bound to a key.

File: gdb.info, Node: Commands For Completion, Next: Keyboard Macros, Prev: Numeric Arguments, Up: Bindable Readline Commands
32.4.6 Letting Readline Type For You
------------------------------------
`complete (<TAB>)'
Attempt to perform completion on the text before point. The
actual completion performed is application-specific. The default
is filename completion.
`possible-completions (M-?)'
List the possible completions of the text before point. When
displaying completions, Readline sets the number of columns used
for display to the value of `completion-display-width', the value
of the environment variable `COLUMNS', or the screen width, in
that order.
`insert-completions (M-*)'
Insert all completions of the text before point that would have
been generated by `possible-completions'.
`menu-complete ()'
Similar to `complete', but replaces the word to be completed with
a single match from the list of possible completions. Repeated
execution of `menu-complete' steps through the list of possible
completions, inserting each match in turn. At the end of the list
of completions, the bell is rung (subject to the setting of
`bell-style') and the original text is restored. An argument of N
moves N positions forward in the list of matches; a negative
argument may be used to move backward through the list. This
command is intended to be bound to <TAB>, but is unbound by
default.
`menu-complete-backward ()'
Identical to `menu-complete', but moves backward through the list
of possible completions, as if `menu-complete' had been given a
negative argument.
`delete-char-or-list ()'
Deletes the character under the cursor if not at the beginning or
end of the line (like `delete-char'). If at the end of the line,
behaves identically to `possible-completions'. This command is
unbound by default.

File: gdb.info, Node: Keyboard Macros, Next: Miscellaneous Commands, Prev: Commands For Completion, Up: Bindable Readline Commands
32.4.7 Keyboard Macros
----------------------
`start-kbd-macro (C-x ()'
Begin saving the characters typed into the current keyboard macro.
`end-kbd-macro (C-x ))'
Stop saving the characters typed into the current keyboard macro
and save the definition.
`call-last-kbd-macro (C-x e)'
Re-execute the last keyboard macro defined, by making the
characters in the macro appear as if typed at the keyboard.

File: gdb.info, Node: Miscellaneous Commands, Prev: Keyboard Macros, Up: Bindable Readline Commands
32.4.8 Some Miscellaneous Commands
----------------------------------
`re-read-init-file (C-x C-r)'
Read in the contents of the INPUTRC file, and incorporate any
bindings or variable assignments found there.
`abort (C-g)'
Abort the current editing command and ring the terminal's bell
(subject to the setting of `bell-style').
`do-uppercase-version (M-a, M-b, M-X, ...)'
If the metafied character X is lowercase, run the command that is
bound to the corresponding uppercase character.
`prefix-meta (<ESC>)'
Metafy the next character typed. This is for keyboards without a
meta key. Typing `<ESC> f' is equivalent to typing `M-f'.
`undo (C-_ or C-x C-u)'
Incremental undo, separately remembered for each line.
`revert-line (M-r)'
Undo all changes made to this line. This is like executing the
`undo' command enough times to get back to the beginning.
`tilde-expand (M-~)'
Perform tilde expansion on the current word.
`set-mark (C-@)'
Set the mark to the point. If a numeric argument is supplied, the
mark is set to that position.
`exchange-point-and-mark (C-x C-x)'
Swap the point with the mark. The current cursor position is set
to the saved position, and the old cursor position is saved as the
mark.
`character-search (C-])'
A character is read and point is moved to the next occurrence of
that character. A negative count searches for previous
occurrences.
`character-search-backward (M-C-])'
A character is read and point is moved to the previous occurrence
of that character. A negative count searches for subsequent
occurrences.
`skip-csi-sequence ()'
Read enough characters to consume a multi-key sequence such as
those defined for keys like Home and End. Such sequences begin
with a Control Sequence Indicator (CSI), usually ESC-[. If this
sequence is bound to "\e[", keys producing such sequences will
have no effect unless explicitly bound to a readline command,
instead of inserting stray characters into the editing buffer.
This is unbound by default, but usually bound to ESC-[.
`insert-comment (M-#)'
Without a numeric argument, the value of the `comment-begin'
variable is inserted at the beginning of the current line. If a
numeric argument is supplied, this command acts as a toggle: if
the characters at the beginning of the line do not match the value
of `comment-begin', the value is inserted, otherwise the
characters in `comment-begin' are deleted from the beginning of
the line. In either case, the line is accepted as if a newline
had been typed.
`dump-functions ()'
Print all of the functions and their key bindings to the Readline
output stream. If a numeric argument is supplied, the output is
formatted in such a way that it can be made part of an INPUTRC
file. This command is unbound by default.
`dump-variables ()'
Print all of the settable variables and their values to the
Readline output stream. If a numeric argument is supplied, the
output is formatted in such a way that it can be made part of an
INPUTRC file. This command is unbound by default.
`dump-macros ()'
Print all of the Readline key sequences bound to macros and the
strings they output. If a numeric argument is supplied, the
output is formatted in such a way that it can be made part of an
INPUTRC file. This command is unbound by default.
`emacs-editing-mode (C-e)'
When in `vi' command mode, this causes a switch to `emacs' editing
mode.
`vi-editing-mode (M-C-j)'
When in `emacs' editing mode, this causes a switch to `vi' editing
mode.

File: gdb.info, Node: Readline vi Mode, Prev: Bindable Readline Commands, Up: Command Line Editing
32.5 Readline vi Mode
=====================
While the Readline library does not have a full set of `vi' editing
functions, it does contain enough to allow simple editing of the line.
The Readline `vi' mode behaves as specified in the POSIX standard.
In order to switch interactively between `emacs' and `vi' editing
modes, use the command `M-C-j' (bound to emacs-editing-mode when in
`vi' mode and to vi-editing-mode in `emacs' mode). The Readline
default is `emacs' mode.
When you enter a line in `vi' mode, you are already placed in
`insertion' mode, as if you had typed an `i'. Pressing <ESC> switches
you into `command' mode, where you can edit the text of the line with
the standard `vi' movement keys, move to previous history lines with
`k' and subsequent lines with `j', and so forth.

File: gdb.info, Node: Using History Interactively, Next: In Memoriam, Prev: Command Line Editing, Up: Top
33 Using History Interactively
******************************
This chapter describes how to use the GNU History Library interactively,
from a user's standpoint. It should be considered a user's guide. For
information on using the GNU History Library in your own programs,
*note Programming with GNU History: (history)Programming with GNU
History.
* Menu:
* History Interaction:: What it feels like using History as a user.

File: gdb.info, Node: History Interaction, Up: Using History Interactively
33.1 History Expansion
======================
The History library provides a history expansion feature that is similar
to the history expansion provided by `csh'. This section describes the
syntax used to manipulate the history information.
History expansions introduce words from the history list into the
input stream, making it easy to repeat commands, insert the arguments
to a previous command into the current input line, or fix errors in
previous commands quickly.
History expansion takes place in two parts. The first is to
determine which line from the history list should be used during
substitution. The second is to select portions of that line for
inclusion into the current one. The line selected from the history is
called the "event", and the portions of that line that are acted upon
are called "words". Various "modifiers" are available to manipulate
the selected words. The line is broken into words in the same fashion
that Bash does, so that several words surrounded by quotes are
considered one word. History expansions are introduced by the
appearance of the history expansion character, which is `!' by default.
* Menu:
* Event Designators:: How to specify which history line to use.
* Word Designators:: Specifying which words are of interest.
* Modifiers:: Modifying the results of substitution.

File: gdb.info, Node: Event Designators, Next: Word Designators, Up: History Interaction
33.1.1 Event Designators
------------------------
An event designator is a reference to a command line entry in the
history list. Unless the reference is absolute, events are relative to
the current position in the history list.
`!'
Start a history substitution, except when followed by a space, tab,
the end of the line, or `='.
`!N'
Refer to command line N.
`!-N'
Refer to the command N lines back.
`!!'
Refer to the previous command. This is a synonym for `!-1'.
`!STRING'
Refer to the most recent command preceding the current position in
the history list starting with STRING.
`!?STRING[?]'
Refer to the most recent command preceding the current position in
the history list containing STRING. The trailing `?' may be
omitted if the STRING is followed immediately by a newline.
`^STRING1^STRING2^'
Quick Substitution. Repeat the last command, replacing STRING1
with STRING2. Equivalent to `!!:s/STRING1/STRING2/'.
`!#'
The entire command line typed so far.

File: gdb.info, Node: Word Designators, Next: Modifiers, Prev: Event Designators, Up: History Interaction
33.1.2 Word Designators
-----------------------
Word designators are used to select desired words from the event. A
`:' separates the event specification from the word designator. It may
be omitted if the word designator begins with a `^', `$', `*', `-', or
`%'. Words are numbered from the beginning of the line, with the first
word being denoted by 0 (zero). Words are inserted into the current
line separated by single spaces.
For example,
`!!'
designates the preceding command. When you type this, the
preceding command is repeated in toto.
`!!:$'
designates the last argument of the preceding command. This may be
shortened to `!$'.
`!fi:2'
designates the second argument of the most recent command starting
with the letters `fi'.
Here are the word designators:
`0 (zero)'
The `0'th word. For many applications, this is the command word.
`N'
The Nth word.
`^'
The first argument; that is, word 1.
`$'
The last argument.
`%'
The word matched by the most recent `?STRING?' search.
`X-Y'
A range of words; `-Y' abbreviates `0-Y'.
`*'
All of the words, except the `0'th. This is a synonym for `1-$'.
It is not an error to use `*' if there is just one word in the
event; the empty string is returned in that case.
`X*'
Abbreviates `X-$'
`X-'
Abbreviates `X-$' like `X*', but omits the last word.
If a word designator is supplied without an event specification, the
previous command is used as the event.

File: gdb.info, Node: Modifiers, Prev: Word Designators, Up: History Interaction
33.1.3 Modifiers
----------------
After the optional word designator, you can add a sequence of one or
more of the following modifiers, each preceded by a `:'.
`h'
Remove a trailing pathname component, leaving only the head.
`t'
Remove all leading pathname components, leaving the tail.
`r'
Remove a trailing suffix of the form `.SUFFIX', leaving the
basename.
`e'
Remove all but the trailing suffix.
`p'
Print the new command but do not execute it.
`s/OLD/NEW/'
Substitute NEW for the first occurrence of OLD in the event line.
Any delimiter may be used in place of `/'. The delimiter may be
quoted in OLD and NEW with a single backslash. If `&' appears in
NEW, it is replaced by OLD. A single backslash will quote the
`&'. The final delimiter is optional if it is the last character
on the input line.
`&'
Repeat the previous substitution.
`g'
`a'
Cause changes to be applied over the entire event line. Used in
conjunction with `s', as in `gs/OLD/NEW/', or with `&'.
`G'
Apply the following `s' modifier once to each word in the event.

File: gdb.info, Node: In Memoriam, Next: Formatting Documentation, Prev: Using History Interactively, Up: Top
Appendix A In Memoriam
**********************
The GDB project mourns the loss of the following long-time contributors:
`Fred Fish'
Fred was a long-standing contributor to GDB (1991-2006), and to
Free Software in general. Outside of GDB, he was known in the
Amiga world for his series of Fish Disks, and the GeekGadget
project.
`Michael Snyder'
Michael was one of the Global Maintainers of the GDB project, with
contributions recorded as early as 1996, until 2011. In addition
to his day to day participation, he was a large driving force
behind adding Reverse Debugging to GDB.
Beyond their technical contributions to the project, they were also
enjoyable members of the Free Software Community. We will miss them.

File: gdb.info, Node: Formatting Documentation, Next: Installing GDB, Prev: In Memoriam, Up: Top
Appendix B Formatting Documentation
***********************************
The GDB 4 release includes an already-formatted reference card, ready
for printing with PostScript or Ghostscript, in the `gdb' subdirectory
of the main source directory(1). If you can use PostScript or
Ghostscript with your printer, you can print the reference card
immediately with `refcard.ps'.
The release also includes the source for the reference card. You
can format it, using TeX, by typing:
make refcard.dvi
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 DVI output program.
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 `texi2roff') to typeset the printed version.
GDB includes an already formatted copy of the on-line Info version
of this manual in the `gdb' subdirectory. The main Info file is
`gdb-7.5/gdb/gdb.info', and it refers to subordinate files matching
`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 `info' subsystem in GNU Emacs or the standalone `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 `texinfo-format-buffer' or `makeinfo'.
If you have `makeinfo' installed, and are in the top level GDB
source directory (`gdb-7.5', in the case of version 7.5), you can make
the Info file by typing:
cd gdb
make gdb.info
If you want to typeset and print copies of this manual, you need TeX,
a program to print its DVI output files, and `texinfo.tex', the Texinfo
definitions file.
TeX is a typesetting program; it does not print files directly, but
produces output files called DVI files. To print a typeset document,
you need a program to print DVI files. If your system has TeX
installed, chances are it has such a program. The precise command to
use depends on your system; `lpr -d' is common; another (for PostScript
devices) is `dvips'. The DVI print command may require a file name
without any extension or a `.dvi' extension.
TeX also requires a macro definitions file called `texinfo.tex'.
This file tells TeX how to typeset a document written in Texinfo
format. On its own, TeX cannot either read or typeset a Texinfo file.
`texinfo.tex' is distributed with GDB and is located in the
`gdb-VERSION-NUMBER/texinfo' directory.
If you have TeX and a DVI printer program installed, you can typeset
and print this manual. First switch to the `gdb' subdirectory of the
main source directory (for example, to `gdb-7.5/gdb') and type:
make gdb.dvi
Then give `gdb.dvi' to your DVI printing program.
---------- Footnotes ----------
(1) In `gdb-7.5/gdb/refcard.ps' of the version 7.5 release.

File: gdb.info, Node: Installing GDB, Next: Maintenance Commands, Prev: Formatting Documentation, Up: Top
Appendix C Installing GDB
*************************
* Menu:
* Requirements:: Requirements for building GDB
* Running Configure:: Invoking the GDB `configure' script
* Separate Objdir:: Compiling GDB in another directory
* Config Names:: Specifying names for hosts and targets
* Configure Options:: Summary of options for configure
* System-wide configuration:: Having a system-wide init file

File: gdb.info, Node: Requirements, Next: Running Configure, Up: Installing GDB
C.1 Requirements for Building GDB
=================================
Building GDB requires various tools and packages to be available.
Other packages will be used only if they are found.
Tools/Packages Necessary for Building GDB
=========================================
ISO C90 compiler
GDB is written in ISO C90. It should be buildable with any
working C90 compiler, e.g. GCC.
Tools/Packages Optional for Building GDB
========================================
Expat
GDB can use the Expat XML parsing library. This library may be
included with your operating system distribution; if it is not, you
can get the latest version from `http://expat.sourceforge.net'.
The `configure' script will search for this library in several
standard locations; if it is installed in an unusual path, you can
use the `--with-libexpat-prefix' option to specify its location.
Expat is used for:
* Remote protocol memory maps (*note Memory Map Format::)
* Target descriptions (*note Target Descriptions::)
* Remote shared library lists (*Note Library List Format::, or
alternatively *note Library List Format for SVR4 Targets::)
* MS-Windows shared libraries (*note Shared Libraries::)
* Traceframe info (*note Traceframe Info Format::)
zlib
GDB will use the `zlib' library, if available, to read compressed
debug sections. Some linkers, such as GNU gold, are capable of
producing binaries with compressed debug sections. If GDB is
compiled with `zlib', it will be able to read the debug
information in such binaries.
The `zlib' library is likely included with your operating system
distribution; if it is not, you can get the latest version from
`http://zlib.net'.
iconv
GDB's features related to character sets (*note Character Sets::)
require a functioning `iconv' implementation. If you are on a GNU
system, then this is provided by the GNU C Library. Some other
systems also provide a working `iconv'.
If GDB is using the `iconv' program which is installed in a
non-standard place, you will need to tell GDB where to find it.
This is done with `--with-iconv-bin' which specifies the directory
that contains the `iconv' program.
On systems without `iconv', you can install GNU Libiconv. If you
have previously installed Libiconv, you can use the
`--with-libiconv-prefix' option to configure.
GDB's top-level `configure' and `Makefile' will arrange to build
Libiconv if a directory named `libiconv' appears in the top-most
source directory. If Libiconv is built this way, and if the
operating system does not provide a suitable `iconv'
implementation, then the just-built library will automatically be
used by GDB. One easy way to set this up is to download GNU
Libiconv, unpack it, and then rename the directory holding the
Libiconv source code to `libiconv'.