<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
<html>
|
<!-- Copyright (C) 1988-2021 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." -->
|
<!-- Created by GNU Texinfo 5.1, http://www.gnu.org/software/texinfo/ -->
|
<head>
|
<title>Debugging with GDB: Commands In Python</title>
|
|
<meta name="description" content="Debugging with GDB: Commands In Python">
|
<meta name="keywords" content="Debugging with GDB: Commands In Python">
|
<meta name="resource-type" content="document">
|
<meta name="distribution" content="global">
|
<meta name="Generator" content="makeinfo">
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
|
<link href="index.html#Top" rel="start" title="Top">
|
<link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index">
|
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
|
<link href="Python-API.html#Python-API" rel="up" title="Python API">
|
<link href="Parameters-In-Python.html#Parameters-In-Python" rel="next" title="Parameters In Python">
|
<link href="Recordings-In-Python.html#Recordings-In-Python" rel="previous" title="Recordings In Python">
|
<style type="text/css">
|
<!--
|
a.summary-letter {text-decoration: none}
|
blockquote.smallquotation {font-size: smaller}
|
div.display {margin-left: 3.2em}
|
div.example {margin-left: 3.2em}
|
div.indentedblock {margin-left: 3.2em}
|
div.lisp {margin-left: 3.2em}
|
div.smalldisplay {margin-left: 3.2em}
|
div.smallexample {margin-left: 3.2em}
|
div.smallindentedblock {margin-left: 3.2em; font-size: smaller}
|
div.smalllisp {margin-left: 3.2em}
|
kbd {font-style:oblique}
|
pre.display {font-family: inherit}
|
pre.format {font-family: inherit}
|
pre.menu-comment {font-family: serif}
|
pre.menu-preformatted {font-family: serif}
|
pre.smalldisplay {font-family: inherit; font-size: smaller}
|
pre.smallexample {font-size: smaller}
|
pre.smallformat {font-family: inherit; font-size: smaller}
|
pre.smalllisp {font-size: smaller}
|
span.nocodebreak {white-space:nowrap}
|
span.nolinebreak {white-space:nowrap}
|
span.roman {font-family:serif; font-weight:normal}
|
span.sansserif {font-family:sans-serif; font-weight:normal}
|
ul.no-bullet {list-style: none}
|
-->
|
</style>
|
|
|
</head>
|
|
<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
|
<a name="Commands-In-Python"></a>
|
<div class="header">
|
<p>
|
Next: <a href="Parameters-In-Python.html#Parameters-In-Python" accesskey="n" rel="next">Parameters In Python</a>, Previous: <a href="Recordings-In-Python.html#Recordings-In-Python" accesskey="p" rel="previous">Recordings In Python</a>, Up: <a href="Python-API.html#Python-API" accesskey="u" rel="up">Python API</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
|
</div>
|
<hr>
|
<a name="Commands-In-Python-1"></a>
|
<h4 class="subsubsection">23.2.2.20 Commands In Python</h4>
|
|
<a name="index-commands-in-python"></a>
|
<a name="index-python-commands-1"></a>
|
<p>You can implement new <small>GDB</small> CLI commands in Python. A CLI
|
command is implemented using an instance of the <code>gdb.Command</code>
|
class, most commonly using a subclass.
|
</p>
|
<dl>
|
<dt><a name="index-Command_002e_005f_005finit_005f_005f"></a>Function: <strong>Command.__init__</strong> <em>(name, <var>command_class</var> <span class="roman">[</span>, <var>completer_class</var> <span class="roman">[</span>, <var>prefix</var><span class="roman">]]</span>)</em></dt>
|
<dd><p>The object initializer for <code>Command</code> registers the new command
|
with <small>GDB</small>. This initializer is normally invoked from the
|
subclass’ own <code>__init__</code> method.
|
</p>
|
<p><var>name</var> is the name of the command. If <var>name</var> consists of
|
multiple words, then the initial words are looked for as prefix
|
commands. In this case, if one of the prefix commands does not exist,
|
an exception is raised.
|
</p>
|
<p>There is no support for multi-line commands.
|
</p>
|
<p><var>command_class</var> should be one of the ‘<samp>COMMAND_</samp>’ constants
|
defined below. This argument tells <small>GDB</small> how to categorize the
|
new command in the help system.
|
</p>
|
<p><var>completer_class</var> is an optional argument. If given, it should be
|
one of the ‘<samp>COMPLETE_</samp>’ constants defined below. This argument
|
tells <small>GDB</small> how to perform completion for this command. If not
|
given, <small>GDB</small> will attempt to complete using the object’s
|
<code>complete</code> method (see below); if no such method is found, an
|
error will occur when completion is attempted.
|
</p>
|
<p><var>prefix</var> is an optional argument. If <code>True</code>, then the new
|
command is a prefix command; sub-commands of this command may be
|
registered.
|
</p>
|
<p>The help text for the new command is taken from the Python
|
documentation string for the command’s class, if there is one. If no
|
documentation string is provided, the default value “This command is
|
not documented.” is used.
|
</p></dd></dl>
|
|
<a name="index-don_0027t-repeat-Python-command"></a>
|
<dl>
|
<dt><a name="index-Command_002edont_005frepeat"></a>Function: <strong>Command.dont_repeat</strong> <em>()</em></dt>
|
<dd><p>By default, a <small>GDB</small> command is repeated when the user enters a
|
blank line at the command prompt. A command can suppress this
|
behavior by invoking the <code>dont_repeat</code> method. This is similar
|
to the user command <code>dont-repeat</code>, see <a href="Define.html#Define">dont-repeat</a>.
|
</p></dd></dl>
|
|
<dl>
|
<dt><a name="index-Command_002einvoke"></a>Function: <strong>Command.invoke</strong> <em>(argument, from_tty)</em></dt>
|
<dd><p>This method is called by <small>GDB</small> when this command is invoked.
|
</p>
|
<p><var>argument</var> is a string. It is the argument to the command, after
|
leading and trailing whitespace has been stripped.
|
</p>
|
<p><var>from_tty</var> is a boolean argument. When true, this means that the
|
command was entered by the user at the terminal; when false it means
|
that the command came from elsewhere.
|
</p>
|
<p>If this method throws an exception, it is turned into a <small>GDB</small>
|
<code>error</code> call. Otherwise, the return value is ignored.
|
</p>
|
<a name="index-gdb_002estring_005fto_005fargv"></a>
|
<p>To break <var>argument</var> up into an argv-like string use
|
<code>gdb.string_to_argv</code>. This function behaves identically to
|
<small>GDB</small>’s internal argument lexer <code>buildargv</code>.
|
It is recommended to use this for consistency.
|
Arguments are separated by spaces and may be quoted.
|
Example:
|
</p>
|
<div class="smallexample">
|
<pre class="smallexample">print gdb.string_to_argv ("1 2\ \\\"3 '4 \"5' \"6 '7\"")
|
['1', '2 "3', '4 "5', "6 '7"]
|
</pre></div>
|
|
</dd></dl>
|
|
<a name="index-completion-of-Python-commands"></a>
|
<dl>
|
<dt><a name="index-Command_002ecomplete"></a>Function: <strong>Command.complete</strong> <em>(text, word)</em></dt>
|
<dd><p>This method is called by <small>GDB</small> when the user attempts
|
completion on this command. All forms of completion are handled by
|
this method, that is, the <tt class="key">TAB</tt> and <tt class="key">M-?</tt> key bindings
|
(see <a href="Completion.html#Completion">Completion</a>), and the <code>complete</code> command (see <a href="Help.html#Help">complete</a>).
|
</p>
|
<p>The arguments <var>text</var> and <var>word</var> are both strings; <var>text</var>
|
holds the complete command line up to the cursor’s location, while
|
<var>word</var> holds the last word of the command line; this is computed
|
using a word-breaking heuristic.
|
</p>
|
<p>The <code>complete</code> method can return several values:
|
</p><ul>
|
<li> If the return value is a sequence, the contents of the sequence are
|
used as the completions. It is up to <code>complete</code> to ensure that the
|
contents actually do complete the word. A zero-length sequence is
|
allowed, it means that there were no completions available. Only
|
string elements of the sequence are used; other elements in the
|
sequence are ignored.
|
|
</li><li> If the return value is one of the ‘<samp>COMPLETE_</samp>’ constants defined
|
below, then the corresponding <small>GDB</small>-internal completion
|
function is invoked, and its result is used.
|
|
</li><li> All other results are treated as though there were no available
|
completions.
|
</li></ul>
|
</dd></dl>
|
|
<p>When a new command is registered, it must be declared as a member of
|
some general class of commands. This is used to classify top-level
|
commands in the on-line help system; note that prefix commands are not
|
listed under their own category but rather that of their top-level
|
command. The available classifications are represented by constants
|
defined in the <code>gdb</code> module:
|
</p>
|
<dl compact="compact">
|
<dd><a name="index-COMMAND_005fNONE"></a>
|
<a name="index-gdb_002eCOMMAND_005fNONE"></a>
|
</dd>
|
<dt><code>gdb.COMMAND_NONE</code></dt>
|
<dd><p>The command does not belong to any particular class. A command in
|
this category will not be displayed in any of the help categories.
|
</p>
|
<a name="index-COMMAND_005fRUNNING"></a>
|
<a name="index-gdb_002eCOMMAND_005fRUNNING"></a>
|
</dd>
|
<dt><code>gdb.COMMAND_RUNNING</code></dt>
|
<dd><p>The command is related to running the inferior. For example,
|
<code>start</code>, <code>step</code>, and <code>continue</code> are in this category.
|
Type <kbd>help running</kbd> at the <small>GDB</small> prompt to see a list of
|
commands in this category.
|
</p>
|
<a name="index-COMMAND_005fDATA"></a>
|
<a name="index-gdb_002eCOMMAND_005fDATA"></a>
|
</dd>
|
<dt><code>gdb.COMMAND_DATA</code></dt>
|
<dd><p>The command is related to data or variables. For example,
|
<code>call</code>, <code>find</code>, and <code>print</code> are in this category. Type
|
<kbd>help data</kbd> at the <small>GDB</small> prompt to see a list of commands
|
in this category.
|
</p>
|
<a name="index-COMMAND_005fSTACK"></a>
|
<a name="index-gdb_002eCOMMAND_005fSTACK"></a>
|
</dd>
|
<dt><code>gdb.COMMAND_STACK</code></dt>
|
<dd><p>The command has to do with manipulation of the stack. For example,
|
<code>backtrace</code>, <code>frame</code>, and <code>return</code> are in this
|
category. Type <kbd>help stack</kbd> at the <small>GDB</small> prompt to see a
|
list of commands in this category.
|
</p>
|
<a name="index-COMMAND_005fFILES"></a>
|
<a name="index-gdb_002eCOMMAND_005fFILES"></a>
|
</dd>
|
<dt><code>gdb.COMMAND_FILES</code></dt>
|
<dd><p>This class is used for file-related commands. For example,
|
<code>file</code>, <code>list</code> and <code>section</code> are in this category.
|
Type <kbd>help files</kbd> at the <small>GDB</small> prompt to see a list of
|
commands in this category.
|
</p>
|
<a name="index-COMMAND_005fSUPPORT"></a>
|
<a name="index-gdb_002eCOMMAND_005fSUPPORT"></a>
|
</dd>
|
<dt><code>gdb.COMMAND_SUPPORT</code></dt>
|
<dd><p>This should be used for “support facilities”, generally meaning
|
things that are useful to the user when interacting with <small>GDB</small>,
|
but not related to the state of the inferior. For example,
|
<code>help</code>, <code>make</code>, and <code>shell</code> are in this category. Type
|
<kbd>help support</kbd> at the <small>GDB</small> prompt to see a list of
|
commands in this category.
|
</p>
|
<a name="index-COMMAND_005fSTATUS"></a>
|
<a name="index-gdb_002eCOMMAND_005fSTATUS"></a>
|
</dd>
|
<dt><code>gdb.COMMAND_STATUS</code></dt>
|
<dd><p>The command is an ‘<samp>info</samp>’-related command, that is, related to the
|
state of <small>GDB</small> itself. For example, <code>info</code>, <code>macro</code>,
|
and <code>show</code> are in this category. Type <kbd>help status</kbd> at the
|
<small>GDB</small> prompt to see a list of commands in this category.
|
</p>
|
<a name="index-COMMAND_005fBREAKPOINTS"></a>
|
<a name="index-gdb_002eCOMMAND_005fBREAKPOINTS"></a>
|
</dd>
|
<dt><code>gdb.COMMAND_BREAKPOINTS</code></dt>
|
<dd><p>The command has to do with breakpoints. For example, <code>break</code>,
|
<code>clear</code>, and <code>delete</code> are in this category. Type <kbd>help
|
breakpoints</kbd> at the <small>GDB</small> prompt to see a list of commands in
|
this category.
|
</p>
|
<a name="index-COMMAND_005fTRACEPOINTS"></a>
|
<a name="index-gdb_002eCOMMAND_005fTRACEPOINTS"></a>
|
</dd>
|
<dt><code>gdb.COMMAND_TRACEPOINTS</code></dt>
|
<dd><p>The command has to do with tracepoints. For example, <code>trace</code>,
|
<code>actions</code>, and <code>tfind</code> are in this category. Type
|
<kbd>help tracepoints</kbd> at the <small>GDB</small> prompt to see a list of
|
commands in this category.
|
</p>
|
<a name="index-COMMAND_005fTUI"></a>
|
<a name="index-gdb_002eCOMMAND_005fTUI"></a>
|
</dd>
|
<dt><code>gdb.COMMAND_TUI</code></dt>
|
<dd><p>The command has to do with the text user interface (see <a href="TUI.html#TUI">TUI</a>).
|
Type <kbd>help tui</kbd> at the <small>GDB</small> prompt to see a list of
|
commands in this category.
|
</p>
|
<a name="index-COMMAND_005fUSER"></a>
|
<a name="index-gdb_002eCOMMAND_005fUSER"></a>
|
</dd>
|
<dt><code>gdb.COMMAND_USER</code></dt>
|
<dd><p>The command is a general purpose command for the user, and typically
|
does not fit in one of the other categories.
|
Type <kbd>help user-defined</kbd> at the <small>GDB</small> prompt to see
|
a list of commands in this category, as well as the list of gdb macros
|
(see <a href="Sequences.html#Sequences">Sequences</a>).
|
</p>
|
<a name="index-COMMAND_005fOBSCURE"></a>
|
<a name="index-gdb_002eCOMMAND_005fOBSCURE"></a>
|
</dd>
|
<dt><code>gdb.COMMAND_OBSCURE</code></dt>
|
<dd><p>The command is only used in unusual circumstances, or is not of
|
general interest to users. For example, <code>checkpoint</code>,
|
<code>fork</code>, and <code>stop</code> are in this category. Type <kbd>help
|
obscure</kbd> at the <small>GDB</small> prompt to see a list of commands in this
|
category.
|
</p>
|
<a name="index-COMMAND_005fMAINTENANCE"></a>
|
<a name="index-gdb_002eCOMMAND_005fMAINTENANCE"></a>
|
</dd>
|
<dt><code>gdb.COMMAND_MAINTENANCE</code></dt>
|
<dd><p>The command is only useful to <small>GDB</small> maintainers. The
|
<code>maintenance</code> and <code>flushregs</code> commands are in this category.
|
Type <kbd>help internals</kbd> at the <small>GDB</small> prompt to see a list of
|
commands in this category.
|
</p></dd>
|
</dl>
|
|
<p>A new command can use a predefined completion function, either by
|
specifying it via an argument at initialization, or by returning it
|
from the <code>complete</code> method. These predefined completion
|
constants are all defined in the <code>gdb</code> module:
|
</p>
|
<dl compact="compact">
|
<dd><a name="index-COMPLETE_005fNONE"></a>
|
</dd>
|
<dt><code>gdb.COMPLETE_NONE</code>
|
<a name="index-gdb_002eCOMPLETE_005fNONE"></a>
|
</dt>
|
<dd><p>This constant means that no completion should be done.
|
</p>
|
<a name="index-COMPLETE_005fFILENAME"></a>
|
</dd>
|
<dt><code>gdb.COMPLETE_FILENAME</code>
|
<a name="index-gdb_002eCOMPLETE_005fFILENAME"></a>
|
</dt>
|
<dd><p>This constant means that filename completion should be performed.
|
</p>
|
<a name="index-COMPLETE_005fLOCATION"></a>
|
</dd>
|
<dt><code>gdb.COMPLETE_LOCATION</code>
|
<a name="index-gdb_002eCOMPLETE_005fLOCATION"></a>
|
</dt>
|
<dd><p>This constant means that location completion should be done.
|
See <a href="Specify-Location.html#Specify-Location">Specify Location</a>.
|
</p>
|
<a name="index-COMPLETE_005fCOMMAND"></a>
|
</dd>
|
<dt><code>gdb.COMPLETE_COMMAND</code>
|
<a name="index-gdb_002eCOMPLETE_005fCOMMAND"></a>
|
</dt>
|
<dd><p>This constant means that completion should examine <small>GDB</small>
|
command names.
|
</p>
|
<a name="index-COMPLETE_005fSYMBOL"></a>
|
</dd>
|
<dt><code>gdb.COMPLETE_SYMBOL</code>
|
<a name="index-gdb_002eCOMPLETE_005fSYMBOL"></a>
|
</dt>
|
<dd><p>This constant means that completion should be done using symbol names
|
as the source.
|
</p>
|
<a name="index-COMPLETE_005fEXPRESSION"></a>
|
</dd>
|
<dt><code>gdb.COMPLETE_EXPRESSION</code>
|
<a name="index-gdb_002eCOMPLETE_005fEXPRESSION"></a>
|
</dt>
|
<dd><p>This constant means that completion should be done on expressions.
|
Often this means completing on symbol names, but some language
|
parsers also have support for completing on field names.
|
</p></dd>
|
</dl>
|
|
<p>The following code snippet shows how a trivial CLI command can be
|
implemented in Python:
|
</p>
|
<div class="smallexample">
|
<pre class="smallexample">class HelloWorld (gdb.Command):
|
"""Greet the whole world."""
|
|
def __init__ (self):
|
super (HelloWorld, self).__init__ ("hello-world", gdb.COMMAND_USER)
|
|
def invoke (self, arg, from_tty):
|
print "Hello, World!"
|
|
HelloWorld ()
|
</pre></div>
|
|
<p>The last line instantiates the class, and is necessary to trigger the
|
registration of the command with <small>GDB</small>. Depending on how the
|
Python code is read into <small>GDB</small>, you may need to import the
|
<code>gdb</code> module explicitly.
|
</p>
|
<hr>
|
<div class="header">
|
<p>
|
Next: <a href="Parameters-In-Python.html#Parameters-In-Python" accesskey="n" rel="next">Parameters In Python</a>, Previous: <a href="Recordings-In-Python.html#Recordings-In-Python" accesskey="p" rel="previous">Recordings In Python</a>, Up: <a href="Python-API.html#Python-API" accesskey="u" rel="up">Python API</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
|
</div>
|
|
|
|
</body>
|
</html>
|
