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   (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
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INFO-DIR-SECTION Software development
START-INFO-DIR-ENTRY
* Gdb: (gdb).                     The GNU debugger.
* gdbserver: (gdb) Server.        The GNU debugging server.
END-INFO-DIR-ENTRY

   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 7.9.

   Copyright (C) 1988-2015 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."

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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::).

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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>.

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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 Breakpoint Information::
* GDB/MI Frame Information::
* GDB/MI Thread Information::
* GDB/MI Ada Exception Information::

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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" "," "msg=" C-STRING [ "," "code=" C-STRING ]'
     The operation failed.  The 'msg=C-STRING' variable contains the
     corresponding error message.

     If present, the 'code=C-STRING' variable provides an error code on
     which consumers can rely on to detect the corresponding error
     condition.  At present, only one error code is defined:

     '"undefined-command"'
          Indicates that the command causing the error does not exist.

'"^exit"'
     GDB has terminated.

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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.

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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.  The CODE field 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.

'=traceframe-changed,num=TFNUM,tracepoint=TPNUM'
'=traceframe-changed,end'
     Reports that the trace frame was changed and its new number is
     TFNUM.  The number of the tracepoint associated with this trace
     frame is TPNUM.

'=tsv-created,name=NAME,initial=INITIAL'
     Reports that the new trace state variable NAME is created with
     initial value INITIAL.

'=tsv-deleted,name=NAME'
'=tsv-deleted'
     Reports that the trace state variable NAME is deleted or all trace
     state variables are deleted.

'=tsv-modified,name=NAME,initial=INITIAL[,current=CURRENT]'
     Reports that the trace state variable NAME is modified with the
     initial value INITIAL.  The current value CURRENT of trace state
     variable is optional and is reported if the current value of trace
     state variable is known.

'=breakpoint-created,bkpt={...}'
'=breakpoint-modified,bkpt={...}'
'=breakpoint-deleted,id=NUMBER'
     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::.  The
     NUMBER is the ordinal number of the breakpoint.

     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.

'=record-started,thread-group="ID"'
'=record-stopped,thread-group="ID"'
     Execution log recording was either started or stopped on an
     inferior.  The ID is the GDB identifier of the thread group
     corresponding to the affected inferior.

'=cmd-param-changed,param=PARAM,value=VALUE'
     Reports that a parameter of the command 'set PARAM' is changed to
     VALUE.  In the multi-word 'set' command, the PARAM is the whole
     parameter list to 'set' command.  For example, In command 'set
     check type on', PARAM is 'check type' and VALUE is 'on'.

'=memory-changed,thread-group=ID,addr=ADDR,len=LEN[,type="code"]'
     Reports that bytes from ADDR to DATA + LEN were written in an
     inferior.  The ID is the identifier of the thread group
     corresponding to the affected inferior.  The optional 'type="code"'
     part is reported if the memory written to holds executable code.

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File: gdb.info,  Node: GDB/MI Breakpoint Information,  Next: GDB/MI Frame Information,  Prev: GDB/MI Async Records,  Up: GDB/MI Output Records

27.5.4 GDB/MI Breakpoint Information
------------------------------------

When GDB reports information about a breakpoint, a tracepoint, a
watchpoint, or a catchpoint, it uses a tuple with the following fields:

'number'
     The breakpoint number.  For a breakpoint that represents one
     location of a multi-location breakpoint, this will be a dotted
     pair, like '1.2'.

'type'
     The type of the breakpoint.  For ordinary breakpoints this will be
     'breakpoint', but many values are possible.

'catch-type'
     If the type of the breakpoint is 'catchpoint', then this indicates
     the exact type of catchpoint.

'disp'
     This is the breakpoint disposition--either 'del', meaning that the
     breakpoint will be deleted at the next stop, or 'keep', meaning
     that the breakpoint will not be deleted.

'enabled'
     This indicates whether the breakpoint is enabled, in which case the
     value is 'y', or disabled, in which case the value is 'n'.  Note
     that this is not the same as the field 'enable'.

'addr'
     The address of the breakpoint.  This may be a hexidecimal number,
     giving the address; or the string '<PENDING>', for a pending
     breakpoint; or the string '<MULTIPLE>', for a breakpoint with
     multiple locations.  This field will not be present if no address
     can be determined.  For example, a watchpoint does not have an
     address.

'func'
     If known, the function in which the breakpoint appears.  If not
     known, this field is not present.

'filename'
     The name of the source file which contains this function, if known.
     If not known, this field is not present.

'fullname'
     The full file name of the source file which contains this function,
     if known.  If not known, this field is not present.

'line'
     The line number at which this breakpoint appears, if known.  If not
     known, this field is not present.

'at'
     If the source file is not known, this field may be provided.  If
     provided, this holds the address of the breakpoint, possibly
     followed by a symbol name.

'pending'
     If this breakpoint is pending, this field is present and holds the
     text used to set the breakpoint, as entered by the user.

'evaluated-by'
     Where this breakpoint's condition is evaluated, either 'host' or
     'target'.

'thread'
     If this is a thread-specific breakpoint, then this identifies the
     thread in which the breakpoint can trigger.

'task'
     If this breakpoint is restricted to a particular Ada task, then
     this field will hold the task identifier.

'cond'
     If the breakpoint is conditional, this is the condition expression.

'ignore'
     The ignore count of the breakpoint.

'enable'
     The enable count of the breakpoint.

'traceframe-usage'
     FIXME.

'static-tracepoint-marker-string-id'
     For a static tracepoint, the name of the static tracepoint marker.

'mask'
     For a masked watchpoint, this is the mask.

'pass'
     A tracepoint's pass count.

'original-location'
     The location of the breakpoint as originally specified by the user.
     This field is optional.

'times'
     The number of times the breakpoint has been hit.

'installed'
     This field is only given for tracepoints.  This is either 'y',
     meaning that the tracepoint is installed, or 'n', meaning that it
     is not.

'what'
     Some extra data, the exact contents of which are type-dependent.

   For example, here is what the output of '-break-insert' (*note GDB/MI
Breakpoint Commands::) might be:

     -> -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",thread-groups=["i1"],
         times="0"}
     <- (gdb)

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27.5.5 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.

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27.5.6 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.

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File: gdb.info,  Node: GDB/MI Ada Exception Information,  Prev: GDB/MI Thread Information,  Up: GDB/MI Output Records

27.5.7 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.

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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",thread-groups=["i1"],
         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)

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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).

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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",thread-groups=["i1"],
     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",thread-groups=["i1"],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",thread-groups=["i1"],
     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",thread-groups=["i1"],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",thread-groups=["i1"],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",thread-groups=["i1"],times="0"}]}
     (gdb)

The '-break-info' Command
-------------------------

Synopsis
........

      -break-info BREAKPOINT

   Get information about a single breakpoint.

   The result is a table of breakpoints.  *Note GDB/MI Breakpoint
Information::, for details on the format of each breakpoint in the
table.

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
......

*Note GDB/MI Breakpoint Information::, for details on the format of the
resulting breakpoint.

   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",thread-groups=["i1"],
     times="0"}
     (gdb)
     -break-insert -t foo
     ^done,bkpt={number="2",addr="0x00010774",file="recursive2.c",
     fullname="/home/foo/recursive2.c,line="11",thread-groups=["i1"],
     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",thread-groups=["i1"],
     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",thread-groups=["i1"],
     times="0"}]}
     (gdb)

The '-dprintf-insert' Command
-----------------------------

Synopsis
........

      -dprintf-insert [ -t ] [ -f ] [ -d ]
         [ -c CONDITION ] [ -i IGNORE-COUNT ]
         [ -p THREAD-ID ] [ LOCATION ] [ FORMAT ]
         [ ARGUMENT ]

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.
'-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.
'-c CONDITION'
     Make the breakpoint conditional on CONDITION.
'-i IGNORE-COUNT'
     Set the ignore count of the breakpoint (*note ignore count:
     Conditions.) to IGNORE-COUNT.
'-p THREAD-ID'
     Restrict the breakpoint to the specified THREAD-ID.

Result
......

*Note GDB/MI Breakpoint Information::, for details on the format of the
resulting breakpoint.

GDB Command
...........

The corresponding GDB command is 'dprintf'.

Example
.......

     (gdb)
     4-dprintf-insert foo "At foo entry\n"
     4^done,bkpt={number="1",type="dprintf",disp="keep",enabled="y",
     addr="0x000000000040061b",func="foo",file="mi-dprintf.c",
     fullname="mi-dprintf.c",line="25",thread-groups=["i1"],
     times="0",script={"printf \"At foo entry\\n\"","continue"},
     original-location="foo"}
     (gdb)
     5-dprintf-insert 26 "arg=%d, g=%d\n" arg g
     5^done,bkpt={number="2",type="dprintf",disp="keep",enabled="y",
     addr="0x000000000040062a",func="foo",file="mi-dprintf.c",
     fullname="mi-dprintf.c",line="26",thread-groups=["i1"],
     times="0",script={"printf \"arg=%d, g=%d\\n\", arg, g","continue"},
     original-location="mi-dprintf.c:26"}
     (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
'Thread-groups'
     list of thread groups to which this breakpoint applies
'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",thread-groups=["i1"],
     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",thread-groups=["i1"],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",thread-groups=["i1"],
     times="1"},
     bkpt={number="2",type="watchpoint",disp="keep",
     enabled="y",addr="",what="C",thread-groups=["i1"],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",thread-groups=["i1"],
     times="1"},
     bkpt={number="2",type="watchpoint",disp="keep",
     enabled="y",addr="",what="C",thread-groups=["i1"],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",
     thread-groups=["i1"],times="1"}]}
     (gdb)

\1f
File: gdb.info,  Node: GDB/MI Catchpoint Commands,  Next: GDB/MI Program Context,  Prev: GDB/MI Breakpoint Commands,  Up: GDB/MI

27.9 GDB/MI Catchpoint Commands
===============================

This section documents GDB/MI commands for manipulating catchpoints.

* Menu:

* Shared Library GDB/MI Catchpoint Commands::
* Ada Exception GDB/MI Catchpoint Commands::

\1f
File: gdb.info,  Node: Shared Library GDB/MI Catchpoint Commands,  Next: Ada Exception GDB/MI Catchpoint Commands,  Up: GDB/MI Catchpoint Commands

27.9.1 Shared Library GDB/MI Catchpoints
----------------------------------------

The '-catch-load' Command
-------------------------

Synopsis
........

      -catch-load [ -t ] [ -d ] REGEXP

   Add a catchpoint for library load events.  If the '-t' option is
used, the catchpoint is a temporary one (*note Setting Breakpoints: Set
Breaks.).  If the '-d' option is used, the catchpoint is created in a
disabled state.  The 'regexp' argument is a regular expression used to
match the name of the loaded library.

GDB Command
...........

The corresponding GDB command is 'catch load'.

Example
.......

     -catch-load -t foo.so
     ^done,bkpt={number="1",type="catchpoint",disp="del",enabled="y",
     what="load of library matching foo.so",catch-type="load",times="0"}
     (gdb)

The '-catch-unload' Command
---------------------------

Synopsis
........

      -catch-unload [ -t ] [ -d ] REGEXP

   Add a catchpoint for library unload events.  If the '-t' option is
used, the catchpoint is a temporary one (*note Setting Breakpoints: Set
Breaks.).  If the '-d' option is used, the catchpoint is created in a
disabled state.  The 'regexp' argument is a regular expression used to
match the name of the unloaded library.

GDB Command
...........

The corresponding GDB command is 'catch unload'.

Example
.......

     -catch-unload -d bar.so
     ^done,bkpt={number="2",type="catchpoint",disp="keep",enabled="n",
     what="load of library matching bar.so",catch-type="unload",times="0"}
     (gdb)

\1f
File: gdb.info,  Node: Ada Exception GDB/MI Catchpoint Commands,  Prev: Shared Library GDB/MI Catchpoint Commands,  Up: GDB/MI Catchpoint Commands

27.9.2 Ada Exception GDB/MI Catchpoints
---------------------------------------

The following GDB/MI commands can be used to create catchpoints that
stop the execution when Ada exceptions are being raised.

The '-catch-assert' Command
---------------------------

Synopsis
........

      -catch-assert [ -c CONDITION] [ -d ] [ -t ]

   Add a catchpoint for failed Ada assertions.

   The possible optional parameters for this command are:

'-c CONDITION'
     Make the catchpoint conditional on CONDITION.
'-d'
     Create a disabled catchpoint.
'-t'
     Create a temporary catchpoint.

GDB Command
...........

The corresponding GDB command is 'catch assert'.

Example
.......

     -catch-assert
     ^done,bkptno="5",bkpt={number="5",type="breakpoint",disp="keep",
     enabled="y",addr="0x0000000000404888",what="failed Ada assertions",
     thread-groups=["i1"],times="0",
     original-location="__gnat_debug_raise_assert_failure"}
     (gdb)

The '-catch-exception' Command
------------------------------

Synopsis
........

      -catch-exception [ -c CONDITION] [ -d ] [ -e EXCEPTION-NAME ]
         [ -t ] [ -u ]

   Add a catchpoint stopping when Ada exceptions are raised.  By
default, the command stops the program when any Ada exception gets
raised.  But it is also possible, by using some of the optional
parameters described below, to create more selective catchpoints.

   The possible optional parameters for this command are:

'-c CONDITION'
     Make the catchpoint conditional on CONDITION.
'-d'
     Create a disabled catchpoint.
'-e EXCEPTION-NAME'
     Only stop when EXCEPTION-NAME is raised.  This option cannot be
     used combined with '-u'.
'-t'
     Create a temporary catchpoint.
'-u'
     Stop only when an unhandled exception gets raised.  This option
     cannot be used combined with '-e'.

GDB Command
...........

The corresponding GDB commands are 'catch exception' and 'catch
exception unhandled'.

Example
.......

     -catch-exception -e Program_Error
     ^done,bkptno="4",bkpt={number="4",type="breakpoint",disp="keep",
     enabled="y",addr="0x0000000000404874",
     what="`Program_Error' Ada exception", thread-groups=["i1"],
     times="0",original-location="__gnat_debug_raise_exception"}
     (gdb)

\1f
File: gdb.info,  Node: GDB/MI Program Context,  Next: GDB/MI Thread Commands,  Prev: GDB/MI Catchpoint Commands,  Up: GDB/MI

27.10 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)

\1f
File: gdb.info,  Node: GDB/MI Thread Commands,  Next: GDB/MI Ada Tasking Commands,  Prev: GDB/MI Program Context,  Up: GDB/MI

27.11 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)

\1f
File: gdb.info,  Node: GDB/MI Ada Tasking Commands,  Next: GDB/MI Program Execution,  Prev: GDB/MI Thread Commands,  Up: GDB/MI

27.12 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)

\1f
File: gdb.info,  Node: GDB/MI Program Execution,  Next: GDB/MI Stack Manipulation,  Prev: GDB/MI Ada Tasking Commands,  Up: GDB/MI

27.13 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 ] [ --start ]

   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 neither the '--all' nor the '--thread-group' 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.

   Using the '--start' option instructs the debugger to stop the
execution at the start of the inferior's main subprogram, following the
same behavior as the 'start' command (*note Starting::).

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)

\1f
File: gdb.info,  Node: GDB/MI Stack Manipulation,  Next: GDB/MI Variable Objects,  Prev: GDB/MI Program Execution,  Up: GDB/MI

27.14 GDB/MI Stack Manipulation Commands
========================================

The '-enable-frame-filters' Command
-----------------------------------

     -enable-frame-filters

   GDB allows Python-based frame filters to affect the output of the MI
commands relating to stack traces.  As there is 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).

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 [ --no-frame-filters ] [ --skip-unavailable ] 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.  If
the option '--no-frame-filters' is supplied, then Python frame filters
will not be executed.

   If the '--skip-unavailable' option is specified, arguments that are
not available are not listed.  Partially available arguments are still
displayed, however.

   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 [ --no-frame-filters 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.  If the
option '--no-frame-filters' is supplied, then Python frame filters will
not be executed.

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 [ --no-frame-filters ] [ --skip-unavailable ] 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.  If the option
'--no-frame-filters' is supplied, then Python frame filters will not be
executed.

   If the '--skip-unavailable' option is specified, local variables that
are not available are not listed.  Partially available local variables
are still displayed, however.

   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 [ --no-frame-filters ] [ --skip-unavailable ] 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.  If the option '--no-frame-filters' is supplied,
then Python frame filters will not be executed.

   If the '--skip-unavailable' option is specified, local variables and
arguments that are not available are not listed.  Partially available
arguments and local variables are still displayed, however.

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)

\1f
File: gdb.info,  Node: GDB/MI Variable Objects,  Next: GDB/MI Data Manipulation,  Prev: GDB/MI Stack Manipulation,  Up: GDB/MI

27.15 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.

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::.

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.

   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 value of 'lang' is the language name, which can be found in
*note Supported Languages::.

   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 Support 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

\1f
File: gdb.info,  Node: GDB/MI Data Manipulation,  Next: GDB/MI Tracepoint Commands,  Prev: GDB/MI Variable Objects,  Up: GDB/MI

27.16 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 result of the '-data-disassemble' command will be a list named
'asm_insns', the contents of this list depend on the MODE used with the
'-data-disassemble' command.

   For modes 0 and 2 the 'asm_insns' list contains tuples with the
following fields:

'address'
     The address at which this instruction was disassembled.

'func-name'
     The name of the function this instruction is within.

'offset'
     The decimal offset in bytes from the start of 'func-name'.

'inst'
     The text disassembly for this 'address'.

'opcodes'
     This field is only present for mode 2.  This contains the raw
     opcode bytes for the 'inst' field.

   For modes 1 and 3 the 'asm_insns' list contains tuples named
'src_and_asm_line', each of which has the following fields:

'line'
     The line number within 'file'.

'file'
     The file name from the compilation unit.  This might be an absolute
     file name or a relative file name depending on the compile command
     used.

'fullname'
     Absolute file name of 'file'.  It is converted to a canonical form
     using the source file search path (*note Specifying Source
     Directories: Source Path.) and after resolving all the symbolic
     links.

     If the source file is not found this field will contain the path as
     present in the debug information.

'line_asm_insn'
     This is a list of tuples containing the disassembly for 'line' in
     'file'.  The fields of each tuple are the same as for
     '-data-disassemble' in MODE 0 and 2, so 'address', 'func-name',
     'offset', 'inst', and optionally 'opcodes'.

   Note that whatever included in the 'inst' field, is not manipulated
directly by GDB/MI, i.e., it is not possible to adjust its format.

GDB Command
...........

The corresponding GDB command is 'disassemble'.

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="../../../src/gdb/testsuite/gdb.mi/basics.c",
     fullname="/absolute/path/to/src/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="../../../src/gdb/testsuite/gdb.mi/basics.c",
     fullname="/absolute/path/to/src/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
         [ --skip-unavailable ] FMT [ ( REGNO )*]

   Display the registers' contents.  The format according to which the
registers' contents are to be returned is given by FMT, 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.  The '--skip-unavailable' option indicates that only the
available registers are to 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
      -data-write-memory-bytes ADDRESS CONTENTS [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.

'CONTENTS'
     The hex-encoded bytes to write.

'COUNT'
     Optional argument indicating the number of bytes to be written.  If
     COUNT is greater than CONTENTS' length, GDB will repeatedly write
     CONTENTS until it fills COUNT bytes.

GDB Command
...........

There's no corresponding GDB command.

Example
.......

     (gdb)
     -data-write-memory-bytes &a "aabbccdd"
     ^done
     (gdb)

     (gdb)
     -data-write-memory-bytes &a "aabbccdd" 16e
     ^done
     (gdb)

\1f
File: gdb.info,  Node: GDB/MI Tracepoint Commands,  Next: GDB/MI Symbol Query,  Prev: GDB/MI Data Manipulation,  Up: GDB/MI

27.17 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'.

The '-trace-frame-collected' Command
------------------------------------

Synopsis
........

      -trace-frame-collected
         [--var-print-values VAR_PVAL]
         [--comp-print-values COMP_PVAL]
         [--registers-format REGFORMAT]
         [--memory-contents]

   This command returns the set of collected objects, register names,
trace state variable names, memory ranges and computed expressions that
have been collected at a particular trace frame.  The optional
parameters to the command affect the output format in different ways.
See the output description table below for more details.

   The reported names can be used in the normal manner to create varobjs
and inspect the objects themselves.  The items returned by this command
are categorized so that it is clear which is a variable, which is a
register, which is a trace state variable, which is a memory range and
which is a computed expression.

   For instance, if the actions were
     collect myVar, myArray[myIndex], myObj.field, myPtr->field, myCount + 2
     collect *(int*)0xaf02bef0@40

the object collected in its entirety would be 'myVar'.  The object
'myArray' would be partially collected, because only the element at
index 'myIndex' would be collected.  The remaining objects would be
computed expressions.

   An example output would be:

     (gdb)
     -trace-frame-collected
     ^done,
       explicit-variables=[{name="myVar",value="1"}],
       computed-expressions=[{name="myArray[myIndex]",value="0"},
                             {name="myObj.field",value="0"},
                             {name="myPtr->field",value="1"},
                             {name="myCount + 2",value="3"},
                             {name="$tvar1 + 1",value="43970027"}],
       registers=[{number="0",value="0x7fe2c6e79ec8"},
                  {number="1",value="0x0"},
                  {number="2",value="0x4"},
                  ...
                  {number="125",value="0x0"}],
       tvars=[{name="$tvar1",current="43970026"}],
       memory=[{address="0x0000000000602264",length="4"},
               {address="0x0000000000615bc0",length="4"}]
     (gdb)

   Where:

'explicit-variables'
     The set of objects that have been collected in their entirety (as
     opposed to collecting just a few elements of an array or a few
     struct members).  For each object, its name and value are printed.
     The '--var-print-values' option affects how or whether the value
     field is output.  If VAR_PVAL is 0, then print only the names; if
     it is 1, print also their values; and if it is 2, print the name,
     type and value for simple data types, and the name and type for
     arrays, structures and unions.

'computed-expressions'
     The set of computed expressions that have been collected at the
     current trace frame.  The '--comp-print-values' option affects this
     set like the '--var-print-values' option affects the
     'explicit-variables' set.  See above.

'registers'
     The registers that have been collected at the current trace frame.
     For each register collected, the name and current value are
     returned.  The value is formatted according to the
     '--registers-format' option.  See the '-data-list-register-values'
     command for a list of the allowed formats.  The default is 'x'.

'tvars'
     The trace state variables that have been collected at the current
     trace frame.  For each trace state variable collected, the name and
     current value are returned.

'memory'
     The set of memory ranges that have been collected at the current
     trace frame.  Its content is a list of tuples.  Each tuple
     represents a collected memory range and has the following fields:

     'address'
          The start address of the memory range, as hexadecimal literal.

     'length'
          The length of the memory range, as decimal literal.

     'contents'
          The contents of the memory block, in hex.  This field is only
          present if the '--memory-contents' option is specified.

GDB Command
...........

There is no corresponding GDB command.

Example
.......

-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.

'trace-file'
     The filename of the trace file being examined.  This field is
     optional, and only present when examining a trace file.

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'.

\1f
File: gdb.info,  Node: GDB/MI Symbol Query,  Next: GDB/MI File Commands,  Prev: GDB/MI Tracepoint Commands,  Up: GDB/MI

27.18 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)

\1f
File: gdb.info,  Node: GDB/MI File Commands,  Next: GDB/MI Target Manipulation,  Prev: GDB/MI Symbol Query,  Up: GDB/MI

27.19 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 both the filename and fullname (absolute file
name) of a source file.

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)

\1f
File: gdb.info,  Node: GDB/MI Target Manipulation,  Next: GDB/MI File Transfer Commands,  Prev: GDB/MI File Commands,  Up: GDB/MI

27.20 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)

\1f
File: gdb.info,  Node: GDB/MI File Transfer Commands,  Next: GDB/MI Ada Exceptions Commands,  Prev: GDB/MI Target Manipulation,  Up: GDB/MI

27.21 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)

\1f
File: gdb.info,  Node: GDB/MI Ada Exceptions Commands,  Next: GDB/MI Support Commands,  Prev: GDB/MI File Transfer Commands,  Up: GDB/MI

27.22 Ada Exceptions GDB/MI Commands
====================================

The '-info-ada-exceptions' Command
----------------------------------

Synopsis
........

      -info-ada-exceptions [ REGEXP]

   List all Ada exceptions defined within the program being debugged.
With a regular expression REGEXP, only those exceptions whose names
match REGEXP are listed.

GDB Command
...........

The corresponding GDB command is 'info exceptions'.

Result
......

The result is a table of Ada exceptions.  The following columns are
defined for each exception:

'name'
     The name of the exception.

'address'
     The address of the exception.

Example
.......

     -info-ada-exceptions aint
     ^done,ada-exceptions={nr_rows="2",nr_cols="2",
     hdr=[{width="1",alignment="-1",col_name="name",colhdr="Name"},
     {width="1",alignment="-1",col_name="address",colhdr="Address"}],
     body=[{name="constraint_error",address="0x0000000000613da0"},
     {name="const.aint_global_e",address="0x0000000000613b00"}]}

Catching Ada Exceptions
-----------------------

The commands describing how to ask GDB to stop when a program raises an
exception are described at *note Ada Exception GDB/MI Catchpoint
Commands::.

\1f
File: gdb.info,  Node: GDB/MI Support Commands,  Next: GDB/MI Miscellaneous Commands,  Prev: GDB/MI Ada Exceptions Commands,  Up: GDB/MI

27.23 GDB/MI Support Commands
=============================

Since new commands and features get regularly added to GDB/MI, some
commands are available to help front-ends query the debugger about
support for these capabilities.  Similarly, it is also possible to query
GDB about target support of certain features.

The '-info-gdb-mi-command' Command
----------------------------------

Synopsis
........

      -info-gdb-mi-command CMD_NAME

   Query support for the GDB/MI command named CMD_NAME.

   Note that the dash ('-') starting all GDB/MI commands is technically
not part of the command name (*note GDB/MI Input Syntax::), and thus
should be omitted in CMD_NAME.  However, for ease of use, this command
also accepts the form with the leading dash.

GDB Command
...........

There is no corresponding GDB command.

Result
......

The result is a tuple.  There is currently only one field:

'exists'
     This field is equal to '"true"' if the GDB/MI command exists,
     '"false"' otherwise.

Example
.......

Here is an example where the GDB/MI command does not exist:

     -info-gdb-mi-command unsupported-command
     ^done,command={exists="false"}

And here is an example where the GDB/MI command is known to the
debugger:

     -info-gdb-mi-command symbol-list-lines
     ^done,command={exists="true"}

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.
'language-option'
     Indicates that all GDB/MI commands accept the '--language' option
     (*note Context management::).
'info-gdb-mi-command'
     Indicates support for the '-info-gdb-mi-command' command.
'undefined-command-error-code'
     Indicates support for the "undefined-command" error code in error
     result records, produced when trying to execute an undefined GDB/MI
     command (*note GDB/MI Result Records::).
'exec-run-start-option'
     Indicates that the '-exec-run' command supports the '--start'
     option (*note GDB/MI Program Execution::).

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-target-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.

\1f
File: gdb.info,  Node: GDB/MI Miscellaneous Commands,  Prev: GDB/MI Support Commands,  Up: GDB/MI

27.24 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-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.

'exit-code'
     The exit code of this group's last exited thread, formatted in
     octal.  This field is only present for thread groups of type
     'process' and only if the process is not running.

'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, 'inferior', whose
value is the identifier of the thread group corresponding to the new
inferior.

Example
-------

     gdb
     -add-inferior
     ^done,inferior="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",thread-groups=["i1"],
     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)

\1f
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.

\1f
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.

\1f
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::).

\1f
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.

\1f
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.

\1f
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.

\1f
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'.  The arguments
     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.

\1f
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.  The ADDR is in the form '0x'
followed by one or more lowercase hex digits (note that this does not
depend on the language).

\1f
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

\1f
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.

\1f
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.

\1f
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.

\1f
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

\1f
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'
     Load the JIT reader named READER, which is a shared object
     specified as either an absolute or a relative file name.  In the
     latter case, GDB will try to load the reader from a pre-configured
     directory, usually 'LIBDIR/gdb/' on a UNIX system (here LIBDIR is
     the system library directory, often '/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-unload' and then invoking
     'jit-reader-load'.

'jit-reader-unload'
     Unload the currently loaded JIT reader.

\1f
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.

\1f
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::

\1f
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::

\1f
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
                       NULL           expression object::
                       otherwise
                       length of
                       *note agent
                       expression
                       object::
actions                variable       numactions number of *note
                                      tracepoint action object::

\1f
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::).  The 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.  The
          GDB_JUMP_PAD_HEAD is updated head of jumppad.  Both of
          TARGET_ADDRESS and GDB_JUMP_PAD_HEAD are 8-byte long.  The
          FJUMP contains a sequence of instructions jump to jumppad
          entry.  The FJUMP_SIZE, 4-byte long, is the size of FJUMP.
     'E NN'
          for an error

'close'
     Closes the in-process agent.  This command is sent when GDB or
     GDBserver is about to kill inferiors.

'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.

\1f
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

\1f
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.

\1f
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.

   * The details of the GDB build-time configuration.  GDB shows these
     details if you invoke it with the '--configuration' command-line
     option, or if you type 'show configuration' at GDB's prompt.

   * 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.

\1f
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.

\1f
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.

\1f
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.

\1f
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.)

\1f
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.

\1f
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'.

\1f
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.

\1f
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.

\1f
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.

\1f
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\\": "\\"

\1f
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

\1f
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

\1f
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".

\1f
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.

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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.

\1f
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.

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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'.

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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.

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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.

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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.

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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.

\1f
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.

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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
(history)Programming with GNU History::.

* Menu:

* History Interaction::         What it feels like using History as a user.

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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.

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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.

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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.

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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.

\1f
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.

\1f
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-7.9/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-7.9', in the case of version 7.9), 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-7.9/gdb') and type:

     make gdb.dvi

   Then give 'gdb.dvi' to your DVI printing program.

   ---------- Footnotes ----------

   (1) In 'gdb-7.9/gdb/refcard.ps' of the version 7.9 release.

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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

\1f
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::)
        * Branch trace (*note Branch Trace 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'.

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File: gdb.info,  Node: Running Configure,  Next: Separate Objdir,  Prev: Requirements,  Up: Installing GDB

C.2 Invoking the GDB 'configure' Script
=======================================

GDB comes with a 'configure' script that automates the process of
preparing GDB for installation; you can then use 'make' to build the
'gdb' program.

   The GDB distribution includes all the source code you need for GDB in
a single directory, whose name is usually composed by appending the
version number to 'gdb'.

   For example, the GDB version 7.9 distribution is in the 'gdb-7.9'
directory.  That directory contains:

'gdb-7.9/configure (and supporting files)'
     script for configuring GDB and all its supporting libraries

'gdb-7.9/gdb'
     the source specific to GDB itself

'gdb-7.9/bfd'
     source for the Binary File Descriptor library

'gdb-7.9/include'
     GNU include files

'gdb-7.9/libiberty'
     source for the '-liberty' free software library

'gdb-7.9/opcodes'
     source for the library of opcode tables and disassemblers

'gdb-7.9/readline'
     source for the GNU command-line interface

'gdb-7.9/glob'
     source for the GNU filename pattern-matching subroutine

'gdb-7.9/mmalloc'
     source for the GNU memory-mapped malloc package

   The simplest way to configure and build GDB is to run 'configure'
from the 'gdb-VERSION-NUMBER' source directory, which in this example is
the 'gdb-7.9' directory.

   First switch to the 'gdb-VERSION-NUMBER' source directory if you are
not already in it; then run 'configure'.  Pass the identifier for the
platform on which GDB will run as an argument.

   For example:

     cd gdb-7.9
     ./configure HOST
     make

where HOST is an identifier such as 'sun4' or 'decstation', that
identifies the platform where GDB will run.  (You can often leave off
HOST; 'configure' tries to guess the correct value by examining your
system.)

   Running 'configure HOST' and then running 'make' builds the 'bfd',
'readline', 'mmalloc', and 'libiberty' libraries, then 'gdb' itself.
The configured source files, and the binaries, are left in the
corresponding source directories.

   'configure' is a Bourne-shell ('/bin/sh') script; if your system does
not recognize this automatically when you run a different shell, you may
need to run 'sh' on it explicitly:

     sh configure HOST

   If you run 'configure' from a directory that contains source
directories for multiple libraries or programs, such as the 'gdb-7.9'
source directory for version 7.9, 'configure' creates configuration
files for every directory level underneath (unless you tell it not to,
with the '--norecursion' option).

   You should run the 'configure' script from the top directory in the
source tree, the 'gdb-VERSION-NUMBER' directory.  If you run 'configure'
from one of the subdirectories, you will configure only that
subdirectory.  That is usually not what you want.  In particular, if you
run the first 'configure' from the 'gdb' subdirectory of the
'gdb-VERSION-NUMBER' directory, you will omit the configuration of
'bfd', 'readline', and other sibling directories of the 'gdb'
subdirectory.  This leads to build errors about missing include files
such as 'bfd/bfd.h'.

   You can install 'gdb' anywhere; it has no hardwired paths.  However,
you should make sure that the shell on your path (named by the 'SHELL'
environment variable) is publicly readable.  Remember that GDB uses the
shell to start your program--some systems refuse to let GDB debug child
processes whose programs are not readable.

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File: gdb.info,  Node: Separate Objdir,  Next: Config Names,  Prev: Running Configure,  Up: Installing GDB

C.3 Compiling GDB in Another Directory
======================================

If you want to run GDB versions for several host or target machines, you
need a different 'gdb' compiled for each combination of host and target.
'configure' is designed to make this easy by allowing you to generate
each configuration in a separate subdirectory, rather than in the source
directory.  If your 'make' program handles the 'VPATH' feature (GNU
'make' does), running 'make' in each of these directories builds the
'gdb' program specified there.

   To build 'gdb' in a separate directory, run 'configure' with the
'--srcdir' option to specify where to find the source.  (You also need
to specify a path to find 'configure' itself from your working
directory.  If the path to 'configure' would be the same as the argument
to '--srcdir', you can leave out the '--srcdir' option; it is assumed.)

   For example, with version 7.9, you can build GDB in a separate
directory for a Sun 4 like this:

     cd gdb-7.9
     mkdir ../gdb-sun4
     cd ../gdb-sun4
     ../gdb-7.9/configure sun4
     make

   When 'configure' builds a configuration using a remote source
directory, it creates a tree for the binaries with the same structure
(and using the same names) as the tree under the source directory.  In
the example, you'd find the Sun 4 library 'libiberty.a' in the directory
'gdb-sun4/libiberty', and GDB itself in 'gdb-sun4/gdb'.

   Make sure that your path to the 'configure' script has just one
instance of 'gdb' in it.  If your path to 'configure' looks like
'../gdb-7.9/gdb/configure', you are configuring only one subdirectory of
GDB, not the whole package.  This leads to build errors about missing
include files such as 'bfd/bfd.h'.

   One popular reason to build several GDB configurations in separate
directories is to configure GDB for cross-compiling (where GDB runs on
one machine--the "host"--while debugging programs that run on another
machine--the "target").  You specify a cross-debugging target by giving
the '--target=TARGET' option to 'configure'.

   When you run 'make' to build a program or library, you must run it in
a configured directory--whatever directory you were in when you called
'configure' (or one of its subdirectories).

   The 'Makefile' that 'configure' generates in each source directory
also runs recursively.  If you type 'make' in a source directory such as
'gdb-7.9' (or in a separate configured directory configured with
'--srcdir=DIRNAME/gdb-7.9'), you will build all the required libraries,
and then build GDB.

   When you have multiple hosts or targets configured in separate
directories, you can run 'make' on them in parallel (for example, if
they are NFS-mounted on each of the hosts); they will not interfere with
each other.

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File: gdb.info,  Node: Config Names,  Next: Configure Options,  Prev: Separate Objdir,  Up: Installing GDB

C.4 Specifying Names for Hosts and Targets
==========================================

The specifications used for hosts and targets in the 'configure' script
are based on a three-part naming scheme, but some short predefined
aliases are also supported.  The full naming scheme encodes three pieces
of information in the following pattern:

     ARCHITECTURE-VENDOR-OS

   For example, you can use the alias 'sun4' as a HOST argument, or as
the value for TARGET in a '--target=TARGET' option.  The equivalent full
name is 'sparc-sun-sunos4'.

   The 'configure' script accompanying GDB does not provide any query
facility to list all supported host and target names or aliases.
'configure' calls the Bourne shell script 'config.sub' to map
abbreviations to full names; you can read the script, if you wish, or
you can use it to test your guesses on abbreviations--for example:

     % sh config.sub i386-linux
     i386-pc-linux-gnu
     % sh config.sub alpha-linux
     alpha-unknown-linux-gnu
     % sh config.sub hp9k700
     hppa1.1-hp-hpux
     % sh config.sub sun4
     sparc-sun-sunos4.1.1
     % sh config.sub sun3
     m68k-sun-sunos4.1.1
     % sh config.sub i986v
     Invalid configuration `i986v': machine `i986v' not recognized

'config.sub' is also distributed in the GDB source directory ('gdb-7.9',
for version 7.9).

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File: gdb.info,  Node: Configure Options,  Next: System-wide configuration,  Prev: Config Names,  Up: Installing GDB

C.5 'configure' Options
=======================

Here is a summary of the 'configure' options and arguments that are most
often useful for building GDB.  'configure' also has several other
options not listed here.  *note (configure.info)What Configure Does::,
for a full explanation of 'configure'.

     configure [--help]
               [--prefix=DIR]
               [--exec-prefix=DIR]
               [--srcdir=DIRNAME]
               [--norecursion] [--rm]
               [--target=TARGET]
               HOST

You may introduce options with a single '-' rather than '--' if you
prefer; but you may abbreviate option names if you use '--'.

'--help'
     Display a quick summary of how to invoke 'configure'.

'--prefix=DIR'
     Configure the source to install programs and files under directory
     'DIR'.

'--exec-prefix=DIR'
     Configure the source to install programs under directory 'DIR'.

'--srcdir=DIRNAME'
     *Warning: using this option requires GNU 'make', or another 'make'
     that implements the 'VPATH' feature.*
     Use this option to make configurations in directories separate from
     the GDB source directories.  Among other things, you can use this
     to build (or maintain) several configurations simultaneously, in
     separate directories.  'configure' writes configuration-specific
     files in the current directory, but arranges for them to use the
     source in the directory DIRNAME.  'configure' creates directories
     under the working directory in parallel to the source directories
     below DIRNAME.

'--norecursion'
     Configure only the directory level where 'configure' is executed;
     do not propagate configuration to subdirectories.

'--target=TARGET'
     Configure GDB for cross-debugging programs running on the specified
     TARGET.  Without this option, GDB is configured to debug programs
     that run on the same machine (HOST) as GDB itself.

     There is no convenient way to generate a list of all available
     targets.

'HOST ...'
     Configure GDB to run on the specified HOST.

     There is no convenient way to generate a list of all available
     hosts.

   There are many other options available as well, but they are
generally needed for special purposes only.

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File: gdb.info,  Node: System-wide configuration,  Prev: Configure Options,  Up: Installing GDB

C.6 System-wide configuration and settings
==========================================

GDB can be configured to have a system-wide init file; this file will be
read and executed at startup (*note What GDB does during startup:
Startup.).

   Here is the corresponding configure option:

'--with-system-gdbinit=FILE'
     Specify that the default location of the system-wide init file is
     FILE.

   If GDB has been configured with the option '--prefix=$prefix', it may
be subject to relocation.  Two possible cases:

   * If the default location of this init file contains '$prefix', it
     will be subject to relocation.  Suppose that the configure options
     are '--prefix=$prefix --with-system-gdbinit=$prefix/etc/gdbinit';
     if GDB is moved from '$prefix' to '$install', the system init file
     is looked for as '$install/etc/gdbinit' instead of
     '$prefix/etc/gdbinit'.

   * By contrast, if the default location does not contain the prefix,
     it will not be relocated.  E.g. if GDB has been configured with
     '--prefix=/usr/local --with-system-gdbinit=/usr/share/gdb/gdbinit',
     then GDB will always look for '/usr/share/gdb/gdbinit', wherever
     GDB is installed.

   If the configured location of the system-wide init file (as given by
the '--with-system-gdbinit' option at configure time) is in the
data-directory (as specified by '--with-gdb-datadir' at configure time)
or in one of its subdirectories, then GDB will look for the system-wide
init file in the directory specified by the '--data-directory'
command-line option.  Note that the system-wide init file is only read
once, during GDB initialization.  If the data-directory is changed after
GDB has started with the 'set data-directory' command, the file will not
be reread.

* Menu:

* System-wide Configuration Scripts::  Installed System-wide Configuration Scripts

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File: gdb.info,  Node: System-wide Configuration Scripts,  Up: System-wide configuration

C.6.1 Installed System-wide Configuration Scripts
-------------------------------------------------

The 'system-gdbinit' directory, located inside the data-directory (as
specified by '--with-gdb-datadir' at configure time) contains a number
of scripts which can be used as system-wide init files.  To
automatically source those scripts at startup, GDB should be configured
with '--with-system-gdbinit'.  Otherwise, any user should be able to
source them by hand as needed.

   The following scripts are currently available:

   * 'elinos.py' This script is useful when debugging a program on an
     ELinOS target.  It takes advantage of the environment variables
     defined in a standard ELinOS environment in order to determine the
     location of the system shared libraries, and then sets the
     'solib-absolute-prefix' and 'solib-search-path' variables
     appropriately.

   * 'wrs-linux.py' This script is useful when debugging a program on a
     target running Wind River Linux.  It expects the 'ENV_PREFIX' to be
     set to the host-side sysroot used by the target system.

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File: gdb.info,  Node: Maintenance Commands,  Next: Remote Protocol,  Prev: Installing GDB,  Up: Top

Appendix D Maintenance Commands
*******************************

In addition to commands intended for GDB users, GDB includes a number of
commands intended for GDB developers, that are not documented elsewhere
in this manual.  These commands are provided here for reference.  (For
commands that turn on debugging messages, see *note Debugging Output::.)

'maint agent [-at LOCATION,] EXPRESSION'
'maint agent-eval [-at LOCATION,] EXPRESSION'
     Translate the given EXPRESSION into remote agent bytecodes.  This
     command is useful for debugging the Agent Expression mechanism
     (*note Agent Expressions::).  The 'agent' version produces an
     expression useful for data collection, such as by tracepoints,
     while 'maint agent-eval' produces an expression that evaluates
     directly to a result.  For instance, a collection expression for
     'globa + globb' will include bytecodes to record four bytes of
     memory at each of the addresses of 'globa' and 'globb', while
     discarding the result of the addition, while an evaluation
     expression will do the addition and return the sum.  If '-at' is
     given, generate remote agent bytecode for LOCATION.  If not,
     generate remote agent bytecode for current frame PC address.

'maint agent-printf FORMAT,EXPR,...'
     Translate the given format string and list of argument expressions
     into remote agent bytecodes and display them as a disassembled
     list.  This command is useful for debugging the agent version of
     dynamic printf (*note Dynamic Printf::).

'maint info breakpoints'
     Using the same format as 'info breakpoints', display both the
     breakpoints you've set explicitly, and those GDB is using for
     internal purposes.  Internal breakpoints are shown with negative
     breakpoint numbers.  The type column identifies what kind of
     breakpoint is shown:

     'breakpoint'
          Normal, explicitly set breakpoint.

     'watchpoint'
          Normal, explicitly set watchpoint.

     'longjmp'
          Internal breakpoint, used to handle correctly stepping through
          'longjmp' calls.

     'longjmp resume'
          Internal breakpoint at the target of a 'longjmp'.

     'until'
          Temporary internal breakpoint used by the GDB 'until' command.

     'finish'
          Temporary internal breakpoint used by the GDB 'finish'
          command.

     'shlib events'
          Shared library events.

'maint info bfds'
     This prints information about each 'bfd' object that is known to
     GDB.  *Note BFD: (bfd)Top.

'set displaced-stepping'
'show displaced-stepping'
     Control whether or not GDB will do "displaced stepping" if the
     target supports it.  Displaced stepping is a way to single-step
     over breakpoints without removing them from the inferior, by
     executing an out-of-line copy of the instruction that was
     originally at the breakpoint location.  It is also known as
     out-of-line single-stepping.

     'set displaced-stepping on'
          If the target architecture supports it, GDB will use displaced
          stepping to step over breakpoints.

     'set displaced-stepping off'
          GDB will not use displaced stepping to step over breakpoints,
          even if such is supported by the target architecture.

     'set displaced-stepping auto'
          This is the default mode.  GDB will use displaced stepping
          only if non-stop mode is active (*note Non-Stop Mode::) and
          the target architecture supports displaced stepping.

'maint check-psymtabs'
     Check the consistency of currently expanded psymtabs versus
     symtabs.  Use this to check, for example, whether a symbol is in
     one but not the other.

'maint check-symtabs'
     Check the consistency of currently expanded symtabs.

'maint expand-symtabs [REGEXP]'
     Expand symbol tables.  If REGEXP is specified, only expand symbol
     tables for file names matching REGEXP.

'maint set catch-demangler-crashes [on|off]'
'maint show catch-demangler-crashes'
     Control whether GDB should attempt to catch crashes in the symbol
     name demangler.  The default is to attempt to catch crashes.  If
     enabled, the first time a crash is caught, a core file is created,
     the offending symbol is displayed and the user is presented with
     the option to terminate the current session.

'maint cplus first_component NAME'
     Print the first C++ class/namespace component of NAME.

'maint cplus namespace'
     Print the list of possible C++ namespaces.

'maint deprecate COMMAND [REPLACEMENT]'
'maint undeprecate COMMAND'
     Deprecate or undeprecate the named COMMAND.  Deprecated commands
     cause GDB to issue a warning when you use them.  The optional
     argument REPLACEMENT says which newer command should be used in
     favor of the deprecated one; if it is given, GDB will mention the
     replacement as part of the warning.

'maint dump-me'
     Cause a fatal signal in the debugger and force it to dump its core.
     This is supported only on systems which support aborting a program
     with the 'SIGQUIT' signal.

'maint internal-error [MESSAGE-TEXT]'
'maint internal-warning [MESSAGE-TEXT]'
'maint demangler-warning [MESSAGE-TEXT]'

     Cause GDB to call the internal function 'internal_error',
     'internal_warning' or 'demangler_warning' and hence behave as
     though an internal problam has been detected.  In addition to
     reporting the internal problem, these functions give the user the
     opportunity to either quit GDB or (for 'internal_error' and
     'internal_warning') create a core file of the current GDB session.

     These commands take an optional parameter MESSAGE-TEXT that is used
     as the text of the error or warning message.

     Here's an example of using 'internal-error':

          (gdb) maint internal-error testing, 1, 2
          .../maint.c:121: internal-error: testing, 1, 2
          A problem internal to GDB has been detected.  Further
          debugging may prove unreliable.
          Quit this debugging session? (y or n) n
          Create a core file? (y or n) n
          (gdb)

'maint set internal-error ACTION [ask|yes|no]'
'maint show internal-error ACTION'
'maint set internal-warning ACTION [ask|yes|no]'
'maint show internal-warning ACTION'
'maint set demangler-warning ACTION [ask|yes|no]'
'maint show demangler-warning ACTION'
     When GDB reports an internal problem (error or warning) it gives
     the user the opportunity to both quit GDB and create a core file of
     the current GDB session.  These commands let you override the
     default behaviour for each particular ACTION, described in the
     table below.

     'quit'
          You can specify that GDB should always (yes) or never (no)
          quit.  The default is to ask the user what to do.

     'corefile'
          You can specify that GDB should always (yes) or never (no)
          create a core file.  The default is to ask the user what to
          do.  Note that there is no 'corefile' option for
          'demangler-warning': demangler warnings always create a core
          file and this cannot be disabled.

'maint packet TEXT'
     If GDB is talking to an inferior via the serial protocol, then this
     command sends the string TEXT to the inferior, and displays the
     response packet.  GDB supplies the initial '$' character, the
     terminating '#' character, and the checksum.

'maint print architecture [FILE]'
     Print the entire architecture configuration.  The optional argument
     FILE names the file where the output goes.

'maint print c-tdesc'
     Print the current target description (*note Target Descriptions::)
     as a C source file.  The created source file can be used in GDB
     when an XML parser is not available to parse the description.

'maint print dummy-frames'
     Prints the contents of GDB's internal dummy-frame stack.

          (gdb) b add
          ...
          (gdb) print add(2,3)
          Breakpoint 2, add (a=2, b=3) at ...
          58      return (a + b);
          The program being debugged stopped while in a function called from GDB.
          ...
          (gdb) maint print dummy-frames
          0xa8206d8: id={stack=0xbfffe734,code=0xbfffe73f,!special}, ptid=process 9353
          (gdb)

     Takes an optional file parameter.

'maint print registers [FILE]'
'maint print raw-registers [FILE]'
'maint print cooked-registers [FILE]'
'maint print register-groups [FILE]'
'maint print remote-registers [FILE]'
     Print GDB's internal register data structures.

     The command 'maint print raw-registers' includes the contents of
     the raw register cache; the command 'maint print cooked-registers'
     includes the (cooked) value of all registers, including registers
     which aren't available on the target nor visible to user; the
     command 'maint print register-groups' includes the groups that each
     register is a member of; and the command 'maint print
     remote-registers' includes the remote target's register numbers and
     offsets in the 'G' packets.

     These commands take an optional parameter, a file name to which to
     write the information.

'maint print reggroups [FILE]'
     Print GDB's internal register group data structures.  The optional
     argument FILE tells to what file to write the information.

     The register groups info looks like this:

          (gdb) maint print reggroups
           Group      Type
           general    user
           float      user
           all        user
           vector     user
           system     user
           save       internal
           restore    internal

'flushregs'
     This command forces GDB to flush its internal register cache.

'maint print objfiles [REGEXP]'
     Print a dump of all known object files.  If REGEXP is specified,
     only print object files whose names match REGEXP.  For each object
     file, this command prints its name, address in memory, and all of
     its psymtabs and symtabs.

'maint print user-registers'
     List all currently available "user registers".  User registers
     typically provide alternate names for actual hardware registers.
     They include the four "standard" registers '$fp', '$pc', '$sp', and
     '$ps'.  *Note standard registers::.  User registers can be used in
     expressions in the same way as the canonical register names, but
     only the latter are listed by the 'info registers' and 'maint print
     registers' commands.

'maint print section-scripts [REGEXP]'
     Print a dump of scripts specified in the '.debug_gdb_section'
     section.  If REGEXP is specified, only print scripts loaded by
     object files matching REGEXP.  For each script, this command prints
     its name as specified in the objfile, and the full path if known.
     *Note dotdebug_gdb_scripts section::.

'maint print statistics'
     This command prints, for each object file in the program, various
     data about that object file followed by the byte cache ("bcache")
     statistics for the object file.  The objfile data includes the
     number of minimal, partial, full, and stabs symbols, the number of
     types defined by the objfile, the number of as yet unexpanded psym
     tables, the number of line tables and string tables, and the amount
     of memory used by the various tables.  The bcache statistics
     include the counts, sizes, and counts of duplicates of all and
     unique objects, max, average, and median entry size, total memory
     used and its overhead and savings, and various measures of the hash
     table size and chain lengths.

'maint print target-stack'
     A "target" is an interface between the debugger and a particular
     kind of file or process.  Targets can be stacked in "strata", so
     that more than one target can potentially respond to a request.  In
     particular, memory accesses will walk down the stack of targets
     until they find a target that is interested in handling that
     particular address.

     This command prints a short description of each layer that was
     pushed on the "target stack", starting from the top layer down to
     the bottom one.

'maint print type EXPR'
     Print the type chain for a type specified by EXPR.  The argument
     can be either a type name or a symbol.  If it is a symbol, the type
     of that symbol is described.  The type chain produced by this
     command is a recursive definition of the data type as stored in
     GDB's data structures, including its flags and contained types.

'maint set dwarf2 always-disassemble'
'maint show dwarf2 always-disassemble'
     Control the behavior of 'info address' when using DWARF debugging
     information.

     The default is 'off', which means that GDB should try to describe a
     variable's location in an easily readable format.  When 'on', GDB
     will instead display the DWARF location expression in an
     assembly-like format.  Note that some locations are too complex for
     GDB to describe simply; in this case you will always see the
     disassembly form.

     Here is an example of the resulting disassembly:

          (gdb) info addr argc
          Symbol "argc" is a complex DWARF expression:
               1: DW_OP_fbreg 0

     For more information on these expressions, see the DWARF standard
     (http://www.dwarfstd.org/).

'maint set dwarf2 max-cache-age'
'maint show dwarf2 max-cache-age'
     Control the DWARF 2 compilation unit cache.

     In object files with inter-compilation-unit references, such as
     those produced by the GCC option '-feliminate-dwarf2-dups', the
     DWARF 2 reader needs to frequently refer to previously read
     compilation units.  This setting controls how long a compilation
     unit will remain in the cache if it is not referenced.  A higher
     limit means that cached compilation units will be stored in memory
     longer, and more total memory will be used.  Setting it to zero
     disables caching, which will slow down GDB startup, but reduce
     memory consumption.

'maint set profile'
'maint show profile'
     Control profiling of GDB.

     Profiling will be disabled until you use the 'maint set profile'
     command to enable it.  When you enable profiling, the system will
     begin collecting timing and execution count data; when you disable
     profiling or exit GDB, the results will be written to a log file.
     Remember that if you use profiling, GDB will overwrite the
     profiling log file (often called 'gmon.out').  If you have a record
     of important profiling data in a 'gmon.out' file, be sure to move
     it to a safe location.

     Configuring with '--enable-profiling' arranges for GDB to be
     compiled with the '-pg' compiler option.

'maint set show-debug-regs'
'maint show show-debug-regs'
     Control whether to show variables that mirror the hardware debug
     registers.  Use 'on' to enable, 'off' to disable.  If enabled, the
     debug registers values are shown when GDB inserts or removes a
     hardware breakpoint or watchpoint, and when the inferior triggers a
     hardware-assisted breakpoint or watchpoint.

'maint set show-all-tib'
'maint show show-all-tib'
     Control whether to show all non zero areas within a 1k block
     starting at thread local base, when using the 'info w32
     thread-information-block' command.

'maint set target-async'
'maint show target-async'
     This controls whether GDB targets operate in synchronous or
     asynchronous mode (*note Background Execution::).  Normally the
     default is asynchronous, if it is available; but this can be
     changed to more easily debug problems occurring only in synchronous
     mode.

'maint set per-command'
'maint show per-command'

     GDB can display the resources used by each command.  This is useful
     in debugging performance problems.

     'maint set per-command space [on|off]'
     'maint show per-command space'
          Enable or disable the printing of the memory used by GDB for
          each command.  If enabled, GDB will display how much memory
          each command took, following the command's own output.  This
          can also be requested by invoking GDB with the '--statistics'
          command-line switch (*note Mode Options::).

     'maint set per-command time [on|off]'
     'maint show per-command time'
          Enable or disable the printing of the execution time of GDB
          for each command.  If enabled, GDB will display how much time
          it took to execute each command, following the command's own
          output.  Both CPU time and wallclock time are printed.
          Printing both is useful when trying to determine whether the
          cost is CPU or, e.g., disk/network latency.  Note that the CPU
          time printed is for GDB only, it does not include the
          execution time of the inferior because there's no mechanism
          currently to compute how much time was spent by GDB and how
          much time was spent by the program been debugged.  This can
          also be requested by invoking GDB with the '--statistics'
          command-line switch (*note Mode Options::).

     'maint set per-command symtab [on|off]'
     'maint show per-command symtab'
          Enable or disable the printing of basic symbol table
          statistics for each command.  If enabled, GDB will display the
          following information:

            a. number of symbol tables
            b. number of primary symbol tables
            c. number of blocks in the blockvector

'maint space VALUE'
     An alias for 'maint set per-command space'.  A non-zero value
     enables it, zero disables it.

'maint time VALUE'
     An alias for 'maint set per-command time'.  A non-zero value
     enables it, zero disables it.

'maint translate-address [SECTION] ADDR'
     Find the symbol stored at the location specified by the address
     ADDR and an optional section name SECTION.  If found, GDB prints
     the name of the closest symbol and an offset from the symbol's
     location to the specified address.  This is similar to the 'info
     address' command (*note Symbols::), except that this command also
     allows to find symbols in other sections.

     If section was not specified, the section in which the symbol was
     found is also printed.  For dynamically linked executables, the
     name of executable or shared library containing the symbol is
     printed as well.

   The following command is useful for non-interactive invocations of
GDB, such as in the test suite.

'set watchdog NSEC'
     Set the maximum number of seconds GDB will wait for the target
     operation to finish.  If this time expires, GDB reports and error
     and the command is aborted.

'show watchdog'
     Show the current setting of the target wait timeout.