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 <a name="Basic-Python"></a>
 <div class="header">
 <p>
 Next: <a href="Exception-Handling.html#Exception-Handling" accesskey="n" rel="next">Exception Handling</a>, Up: <a href="Python-API.html#Python-API" accesskey="u" rel="up">Python API</a> &nbsp; [<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="Basic-Python-1"></a>
 <h4 class="subsubsection">23.2.2.1 Basic Python</h4>

 <a name="index-python-stdout"></a>
 <a name="index-python-pagination"></a>
 <p>At startup, <small>GDB</small> overrides Python&rsquo;s <code>sys.stdout</code> and
 <code>sys.stderr</code> to print using <small>GDB</small>&rsquo;s output-paging streams.
 A Python program which outputs to one of these streams may have its
 output interrupted by the user (see <a href="Screen-Size.html#Screen-Size">Screen Size</a>).  In this
 situation, a Python <code>KeyboardInterrupt</code> exception is thrown.
 </p>
 <p>Some care must be taken when writing Python code to run in
 <small>GDB</small>.  Two things worth noting in particular:
 </p>
 <ul>
 <li> <small>GDB</small> install handlers for <code>SIGCHLD</code> and <code>SIGINT</code>.
 Python code must not override these, or even change the options using
 <code>sigaction</code>.  If your program changes the handling of these
 signals, <small>GDB</small> will most likely stop working correctly.  Note
 that it is unfortunately common for GUI toolkits to install a
 <code>SIGCHLD</code> handler.

 </li><li> <small>GDB</small> takes care to mark its internal file descriptors as
 close-on-exec.  However, this cannot be done in a thread-safe way on
 all platforms.  Your Python programs should be aware of this and
 should both create new file descriptors with the close-on-exec flag
 set and arrange to close unneeded file descriptors before starting a
 child process.
 </li></ul>

 <a name="index-python-functions"></a>
 <a name="index-python-module"></a>
 <a name="index-gdb-module"></a>
 <p><small>GDB</small> introduces a new Python module, named <code>gdb</code>.  All
 methods and classes added by <small>GDB</small> are placed in this module.
 <small>GDB</small> automatically <code>import</code>s the <code>gdb</code> module for
 use in all scripts evaluated by the <code>python</code> command.
 </p>
 <a name="index-gdb_002ePYTHONDIR"></a>
 <dl>
 <dt><a name="index-gdb_002ePYTHONDIR-1"></a>Variable: <strong>gdb.PYTHONDIR</strong></dt>
 <dd><p>A string containing the python directory (see <a href="Python.html#Python">Python</a>).
 </p></dd></dl>

 <a name="index-gdb_002eexecute"></a>
 <dl>
 <dt><a name="index-gdb_002eexecute-1"></a>Function: <strong>gdb.execute</strong> <em>(command <span class="roman">[</span>, from_tty <span class="roman">[</span>, to_string<span class="roman">]]</span>)</em></dt>
 <dd><p>Evaluate <var>command</var>, a string, as a <small>GDB</small> CLI command.
 If a GDB exception happens while <var>command</var> runs, it is
 translated as described in <a href="Exception-Handling.html#Exception-Handling">Exception Handling</a>.
 </p>
 <p>The <var>from_tty</var> flag specifies whether <small>GDB</small> ought to consider this
 command as having originated from the user invoking it interactively.
 It must be a boolean value.  If omitted, it defaults to <code>False</code>.
 </p>
 <p>By default, any output produced by <var>command</var> is sent to
 <small>GDB</small>&rsquo;s standard output (and to the log output if logging is
 turned on).  If the <var>to_string</var> parameter is
 <code>True</code>, then output will be collected by <code>gdb.execute</code> and
 returned as a string.  The default is <code>False</code>, in which case the
 return value is <code>None</code>.  If <var>to_string</var> is <code>True</code>, the
 <small>GDB</small> virtual terminal will be temporarily set to unlimited width
 and height, and its pagination will be disabled; see <a href="Screen-Size.html#Screen-Size">Screen Size</a>.
 </p></dd></dl>

 <a name="index-gdb_002ebreakpoints"></a>
 <dl>
 <dt><a name="index-gdb_002ebreakpoints-1"></a>Function: <strong>gdb.breakpoints</strong> <em>()</em></dt>
 <dd><p>Return a sequence holding all of <small>GDB</small>&rsquo;s breakpoints.
 See <a href="Breakpoints-In-Python.html#Breakpoints-In-Python">Breakpoints In Python</a>, for more information.
 </p></dd></dl>

 <a name="index-gdb_002eparameter"></a>
 <dl>
 <dt><a name="index-gdb_002eparameter-1"></a>Function: <strong>gdb.parameter</strong> <em>(parameter)</em></dt>
 <dd><p>Return the value of a <small>GDB</small> <var>parameter</var> given by its name,
 a string; the parameter name string may contain spaces if the parameter has a
 multi-part name.  For example, &lsquo;<samp>print object</samp>&rsquo; is a valid
 parameter name.
 </p>
 <p>If the named parameter does not exist, this function throws a
 <code>gdb.error</code> (see <a href="Exception-Handling.html#Exception-Handling">Exception Handling</a>).  Otherwise, the
 parameter&rsquo;s value is converted to a Python value of the appropriate
 type, and returned.
 </p></dd></dl>

 <a name="index-gdb_002ehistory"></a>
 <dl>
 <dt><a name="index-gdb_002ehistory-1"></a>Function: <strong>gdb.history</strong> <em>(number)</em></dt>
 <dd><p>Return a value from <small>GDB</small>&rsquo;s value history (see <a href="Value-History.html#Value-History">Value History</a>).  The <var>number</var> argument indicates which history element to return.
 If <var>number</var> is negative, then <small>GDB</small> will take its absolute value
 and count backward from the last element (i.e., the most recent element) to
 find the value to return.  If <var>number</var> is zero, then <small>GDB</small> will
 return the most recent element.  If the element specified by <var>number</var>
 doesn&rsquo;t exist in the value history, a <code>gdb.error</code> exception will be
 raised.
 </p>
 <p>If no exception is raised, the return value is always an instance of
 <code>gdb.Value</code> (see <a href="Values-From-Inferior.html#Values-From-Inferior">Values From Inferior</a>).
 </p></dd></dl>

 <a name="index-gdb_002eparse_005fand_005feval"></a>
 <dl>
 <dt><a name="index-gdb_002eparse_005fand_005feval-1"></a>Function: <strong>gdb.parse_and_eval</strong> <em>(expression)</em></dt>
 <dd><p>Parse <var>expression</var>, which must be a string, as an expression in
 the current language, evaluate it, and return the result as a
 <code>gdb.Value</code>.
 </p>
 <p>This function can be useful when implementing a new command
 (see <a href="Commands-In-Python.html#Commands-In-Python">Commands In Python</a>), as it provides a way to parse the
 command&rsquo;s argument as an expression.  It is also useful simply to
 compute values, for example, it is the only way to get the value of a
 convenience variable (see <a href="Convenience-Vars.html#Convenience-Vars">Convenience Vars</a>) as a <code>gdb.Value</code>.
 </p></dd></dl>

 <a name="index-gdb_002efind_005fpc_005fline"></a>
 <dl>
 <dt><a name="index-gdb_002efind_005fpc_005fline-1"></a>Function: <strong>gdb.find_pc_line</strong> <em>(pc)</em></dt>
 <dd><p>Return the <code>gdb.Symtab_and_line</code> object corresponding to the
 <var>pc</var> value.  See <a href="Symbol-Tables-In-Python.html#Symbol-Tables-In-Python">Symbol Tables In Python</a>.  If an invalid
 value of <var>pc</var> is passed as an argument, then the <code>symtab</code> and
 <code>line</code> attributes of the returned <code>gdb.Symtab_and_line</code> object
 will be <code>None</code> and 0 respectively.
 </p></dd></dl>

 <a name="index-gdb_002epost_005fevent"></a>
 <dl>
 <dt><a name="index-gdb_002epost_005fevent-1"></a>Function: <strong>gdb.post_event</strong> <em>(event)</em></dt>
 <dd><p>Put <var>event</var>, a callable object taking no arguments, into
 <small>GDB</small>&rsquo;s internal event queue.  This callable will be invoked at
 some later point, during <small>GDB</small>&rsquo;s event processing.  Events
 posted using <code>post_event</code> will be run in the order in which they
 were posted; however, there is no way to know when they will be
 processed relative to other events inside <small>GDB</small>.
 </p>
 <p><small>GDB</small> is not thread-safe.  If your Python program uses multiple
 threads, you must be careful to only call <small>GDB</small>-specific
 functions in the <small>GDB</small> thread.  <code>post_event</code> ensures
 this.  For example:
 </p>
 <div class="smallexample">
 <pre class="smallexample">(gdb) python
 &gt;import threading
 &gt;
 &gt;class Writer():
 &gt; def __init__(self, message):
 &gt;        self.message = message;
 &gt; def __call__(self):
 &gt;        gdb.write(self.message)
 &gt;
 &gt;class MyThread1 (threading.Thread):
 &gt; def run (self):
 &gt;        gdb.post_event(Writer(&quot;Hello &quot;))
 &gt;
 &gt;class MyThread2 (threading.Thread):
 &gt; def run (self):
 &gt;        gdb.post_event(Writer(&quot;World\n&quot;))
 &gt;
 &gt;MyThread1().start()
 &gt;MyThread2().start()
 &gt;end
 (gdb) Hello World
 </pre></div>
 </dd></dl>

 <a name="index-gdb_002ewrite"></a>
 <dl>
 <dt><a name="index-gdb_002ewrite-1"></a>Function: <strong>gdb.write</strong> <em>(string <span class="roman">[</span>, stream])</em></dt>
 <dd><p>Print a string to <small>GDB</small>&rsquo;s paginated output stream.  The
 optional <var>stream</var> determines the stream to print to.  The default
 stream is <small>GDB</small>&rsquo;s standard output stream.  Possible stream
 values are:
 </p>
 <dl compact="compact">
 <dd><a name="index-STDOUT"></a>
 <a name="index-gdb_002eSTDOUT"></a>
 </dd>
 <dt><code>gdb.STDOUT</code></dt>
 <dd><p><small>GDB</small>&rsquo;s standard output stream.
 </p>
 <a name="index-STDERR"></a>
 <a name="index-gdb_002eSTDERR"></a>
 </dd>
 <dt><code>gdb.STDERR</code></dt>
 <dd><p><small>GDB</small>&rsquo;s standard error stream.
 </p>
 <a name="index-STDLOG"></a>
 <a name="index-gdb_002eSTDLOG"></a>
 </dd>
 <dt><code>gdb.STDLOG</code></dt>
 <dd><p><small>GDB</small>&rsquo;s log stream (see <a href="Logging-Output.html#Logging-Output">Logging Output</a>).
 </p></dd>
 </dl>

 <p>Writing to <code>sys.stdout</code> or <code>sys.stderr</code> will automatically
 call this function and will automatically direct the output to the
 relevant stream.
 </p></dd></dl>

 <a name="index-gdb_002eflush"></a>
 <dl>
 <dt><a name="index-gdb_002eflush-1"></a>Function: <strong>gdb.flush</strong> <em>()</em></dt>
 <dd><p>Flush the buffer of a <small>GDB</small> paginated stream so that the
 contents are displayed immediately.  <small>GDB</small> will flush the
 contents of a stream automatically when it encounters a newline in the
 buffer.  The optional <var>stream</var> determines the stream to flush.  The
 default stream is <small>GDB</small>&rsquo;s standard output stream.  Possible
 stream values are:
 </p>
 <dl compact="compact">
 <dd><a name="index-STDOUT-1"></a>
 <a name="index-gdb_002eSTDOUT-1"></a>
 </dd>
 <dt><code>gdb.STDOUT</code></dt>
 <dd><p><small>GDB</small>&rsquo;s standard output stream.
 </p>
 <a name="index-STDERR-1"></a>
 <a name="index-gdb_002eSTDERR-1"></a>
 </dd>
 <dt><code>gdb.STDERR</code></dt>
 <dd><p><small>GDB</small>&rsquo;s standard error stream.
 </p>
 <a name="index-STDLOG-1"></a>
 <a name="index-gdb_002eSTDLOG-1"></a>
 </dd>
 <dt><code>gdb.STDLOG</code></dt>
 <dd><p><small>GDB</small>&rsquo;s log stream (see <a href="Logging-Output.html#Logging-Output">Logging Output</a>).
 </p>
 </dd>
 </dl>

 <p>Flushing <code>sys.stdout</code> or <code>sys.stderr</code> will automatically
 call this function for the relevant stream.
 </p></dd></dl>

 <a name="index-gdb_002etarget_005fcharset"></a>
 <dl>
 <dt><a name="index-gdb_002etarget_005fcharset-1"></a>Function: <strong>gdb.target_charset</strong> <em>()</em></dt>
 <dd><p>Return the name of the current target character set (see <a href="Character-Sets.html#Character-Sets">Character Sets</a>).  This differs from <code>gdb.parameter('target-charset')</code> in
 that &lsquo;<samp>auto</samp>&rsquo; is never returned.
 </p></dd></dl>

 <a name="index-gdb_002etarget_005fwide_005fcharset"></a>
 <dl>
 <dt><a name="index-gdb_002etarget_005fwide_005fcharset-1"></a>Function: <strong>gdb.target_wide_charset</strong> <em>()</em></dt>
 <dd><p>Return the name of the current target wide character set
 (see <a href="Character-Sets.html#Character-Sets">Character Sets</a>).  This differs from
 <code>gdb.parameter('target-wide-charset')</code> in that &lsquo;<samp>auto</samp>&rsquo; is
 never returned.
 </p></dd></dl>

 <a name="index-gdb_002esolib_005fname"></a>
 <dl>
 <dt><a name="index-gdb_002esolib_005fname-1"></a>Function: <strong>gdb.solib_name</strong> <em>(address)</em></dt>
 <dd><p>Return the name of the shared library holding the given <var>address</var>
 as a string, or <code>None</code>.
 </p></dd></dl>

 <a name="index-gdb_002edecode_005fline"></a>
 <dl>
 <dt><a name="index-gdb_002edecode_005fline-1"></a>Function: <strong>gdb.decode_line</strong> <em><span class="roman">[</span>expression<span class="roman">]</span></em></dt>
 <dd><p>Return locations of the line specified by <var>expression</var>, or of the
 current line if no argument was given.  This function returns a Python
 tuple containing two elements.  The first element contains a string
 holding any unparsed section of <var>expression</var> (or <code>None</code> if
 the expression has been fully parsed).  The second element contains
 either <code>None</code> or another tuple that contains all the locations
 that match the expression represented as <code>gdb.Symtab_and_line</code>
 objects (see <a href="Symbol-Tables-In-Python.html#Symbol-Tables-In-Python">Symbol Tables In Python</a>).  If <var>expression</var> is
 provided, it is decoded the way that <small>GDB</small>&rsquo;s inbuilt
 <code>break</code> or <code>edit</code> commands do (see <a href="Specify-Location.html#Specify-Location">Specify Location</a>).
 </p></dd></dl>

 <dl>
 <dt><a name="index-gdb_002eprompt_005fhook"></a>Function: <strong>gdb.prompt_hook</strong> <em>(current_prompt)</em></dt>
 <dd><a name="prompt_005fhook"></a>
 <p>If <var>prompt_hook</var> is callable, <small>GDB</small> will call the method
 assigned to this operation before a prompt is displayed by
 <small>GDB</small>.
 </p>
 <p>The parameter <code>current_prompt</code> contains the current <small>GDB</small>
 prompt.  This method must return a Python string, or <code>None</code>.  If
 a string is returned, the <small>GDB</small> prompt will be set to that
 string.  If <code>None</code> is returned, <small>GDB</small> will continue to use
 the current prompt.
 </p>
 <p>Some prompts cannot be substituted in <small>GDB</small>.  Secondary prompts
 such as those used by readline for command input, and annotation
 related prompts are prohibited from being changed.
 </p></dd></dl>

 <hr>
 <div class="header">
 <p>
 Next: <a href="Exception-Handling.html#Exception-Handling" accesskey="n" rel="next">Exception Handling</a>, Up: <a href="Python-API.html#Python-API" accesskey="u" rel="up">Python API</a> &nbsp; [<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>
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	<a name="Basic-Python"></a>
	<div class="header">
	<p>
	Next: <a href="Exception-Handling.html#Exception-Handling" accesskey="n" rel="next">Exception Handling</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="Basic-Python-1"></a>
	<h4 class="subsubsection">23.2.2.1 Basic Python</h4>

	<a name="index-python-stdout"></a>
	<a name="index-python-pagination"></a>
	<p>At startup, <small>GDB</small> overrides Python’s <code>sys.stdout</code> and
	<code>sys.stderr</code> to print using <small>GDB</small>’s output-paging streams.
	A Python program which outputs to one of these streams may have its
	output interrupted by the user (see <a href="Screen-Size.html#Screen-Size">Screen Size</a>). In this
	situation, a Python <code>KeyboardInterrupt</code> exception is thrown.
	</p>
	<p>Some care must be taken when writing Python code to run in
	<small>GDB</small>. Two things worth noting in particular:
	</p>
	<ul>
	<li> <small>GDB</small> install handlers for <code>SIGCHLD</code> and <code>SIGINT</code>.
	Python code must not override these, or even change the options using
	<code>sigaction</code>. If your program changes the handling of these
	signals, <small>GDB</small> will most likely stop working correctly. Note
	that it is unfortunately common for GUI toolkits to install a
	<code>SIGCHLD</code> handler.

	</li><li> <small>GDB</small> takes care to mark its internal file descriptors as
	close-on-exec. However, this cannot be done in a thread-safe way on
	all platforms. Your Python programs should be aware of this and
	should both create new file descriptors with the close-on-exec flag
	set and arrange to close unneeded file descriptors before starting a
	child process.
	</li></ul>

	<a name="index-python-functions"></a>
	<a name="index-python-module"></a>
	<a name="index-gdb-module"></a>
	<p><small>GDB</small> introduces a new Python module, named <code>gdb</code>. All
	methods and classes added by <small>GDB</small> are placed in this module.
	<small>GDB</small> automatically <code>import</code>s the <code>gdb</code> module for
	use in all scripts evaluated by the <code>python</code> command.
	</p>
	<a name="index-gdb_002ePYTHONDIR"></a>
	<dl>
	<dt><a name="index-gdb_002ePYTHONDIR-1"></a>Variable: <strong>gdb.PYTHONDIR</strong></dt>
	<dd><p>A string containing the python directory (see <a href="Python.html#Python">Python</a>).
	</p></dd></dl>

	<a name="index-gdb_002eexecute"></a>
	<dl>
	<dt><a name="index-gdb_002eexecute-1"></a>Function: <strong>gdb.execute</strong> <em>(command <span class="roman">[</span>, from_tty <span class="roman">[</span>, to_string<span class="roman">]]</span>)</em></dt>
	<dd><p>Evaluate <var>command</var>, a string, as a <small>GDB</small> CLI command.
	If a GDB exception happens while <var>command</var> runs, it is
	translated as described in <a href="Exception-Handling.html#Exception-Handling">Exception Handling</a>.
	</p>
	<p>The <var>from_tty</var> flag specifies whether <small>GDB</small> ought to consider this
	command as having originated from the user invoking it interactively.
	It must be a boolean value. If omitted, it defaults to <code>False</code>.
	</p>
	<p>By default, any output produced by <var>command</var> is sent to
	<small>GDB</small>’s standard output (and to the log output if logging is
	turned on). If the <var>to_string</var> parameter is
	<code>True</code>, then output will be collected by <code>gdb.execute</code> and
	returned as a string. The default is <code>False</code>, in which case the
	return value is <code>None</code>. If <var>to_string</var> is <code>True</code>, the
	<small>GDB</small> virtual terminal will be temporarily set to unlimited width
	and height, and its pagination will be disabled; see <a href="Screen-Size.html#Screen-Size">Screen Size</a>.
	</p></dd></dl>

	<a name="index-gdb_002ebreakpoints"></a>
	<dl>
	<dt><a name="index-gdb_002ebreakpoints-1"></a>Function: <strong>gdb.breakpoints</strong> <em>()</em></dt>
	<dd><p>Return a sequence holding all of <small>GDB</small>’s breakpoints.
	See <a href="Breakpoints-In-Python.html#Breakpoints-In-Python">Breakpoints In Python</a>, for more information.
	</p></dd></dl>

	<a name="index-gdb_002eparameter"></a>
	<dl>
	<dt><a name="index-gdb_002eparameter-1"></a>Function: <strong>gdb.parameter</strong> <em>(parameter)</em></dt>
	<dd><p>Return the value of a <small>GDB</small> <var>parameter</var> given by its name,
	a string; the parameter name string may contain spaces if the parameter has a
	multi-part name. For example, ‘<samp>print object</samp>’ is a valid
	parameter name.
	</p>
	<p>If the named parameter does not exist, this function throws a
	<code>gdb.error</code> (see <a href="Exception-Handling.html#Exception-Handling">Exception Handling</a>). Otherwise, the
	parameter’s value is converted to a Python value of the appropriate
	type, and returned.
	</p></dd></dl>

	<a name="index-gdb_002ehistory"></a>
	<dl>
	<dt><a name="index-gdb_002ehistory-1"></a>Function: <strong>gdb.history</strong> <em>(number)</em></dt>
	<dd><p>Return a value from <small>GDB</small>’s value history (see <a href="Value-History.html#Value-History">Value History</a>). The <var>number</var> argument indicates which history element to return.
	If <var>number</var> is negative, then <small>GDB</small> will take its absolute value
	and count backward from the last element (i.e., the most recent element) to
	find the value to return. If <var>number</var> is zero, then <small>GDB</small> will
	return the most recent element. If the element specified by <var>number</var>
	doesn’t exist in the value history, a <code>gdb.error</code> exception will be
	raised.
	</p>
	<p>If no exception is raised, the return value is always an instance of
	<code>gdb.Value</code> (see <a href="Values-From-Inferior.html#Values-From-Inferior">Values From Inferior</a>).
	</p></dd></dl>

	<a name="index-gdb_002eparse_005fand_005feval"></a>
	<dl>
	<dt><a name="index-gdb_002eparse_005fand_005feval-1"></a>Function: <strong>gdb.parse_and_eval</strong> <em>(expression)</em></dt>
	<dd><p>Parse <var>expression</var>, which must be a string, as an expression in
	the current language, evaluate it, and return the result as a
	<code>gdb.Value</code>.
	</p>
	<p>This function can be useful when implementing a new command
	(see <a href="Commands-In-Python.html#Commands-In-Python">Commands In Python</a>), as it provides a way to parse the
	command’s argument as an expression. It is also useful simply to
	compute values, for example, it is the only way to get the value of a
	convenience variable (see <a href="Convenience-Vars.html#Convenience-Vars">Convenience Vars</a>) as a <code>gdb.Value</code>.
	</p></dd></dl>

	<a name="index-gdb_002efind_005fpc_005fline"></a>
	<dl>
	<dt><a name="index-gdb_002efind_005fpc_005fline-1"></a>Function: <strong>gdb.find_pc_line</strong> <em>(pc)</em></dt>
	<dd><p>Return the <code>gdb.Symtab_and_line</code> object corresponding to the
	<var>pc</var> value. See <a href="Symbol-Tables-In-Python.html#Symbol-Tables-In-Python">Symbol Tables In Python</a>. If an invalid
	value of <var>pc</var> is passed as an argument, then the <code>symtab</code> and
	<code>line</code> attributes of the returned <code>gdb.Symtab_and_line</code> object
	will be <code>None</code> and 0 respectively.
	</p></dd></dl>

	<a name="index-gdb_002epost_005fevent"></a>
	<dl>
	<dt><a name="index-gdb_002epost_005fevent-1"></a>Function: <strong>gdb.post_event</strong> <em>(event)</em></dt>
	<dd><p>Put <var>event</var>, a callable object taking no arguments, into
	<small>GDB</small>’s internal event queue. This callable will be invoked at
	some later point, during <small>GDB</small>’s event processing. Events
	posted using <code>post_event</code> will be run in the order in which they
	were posted; however, there is no way to know when they will be
	processed relative to other events inside <small>GDB</small>.
	</p>
	<p><small>GDB</small> is not thread-safe. If your Python program uses multiple
	threads, you must be careful to only call <small>GDB</small>-specific
	functions in the <small>GDB</small> thread. <code>post_event</code> ensures
	this. For example:
	</p>
	<div class="smallexample">
	<pre class="smallexample">(gdb) python
	>import threading
	>
	>class Writer():
	> def __init__(self, message):
	> self.message = message;
	> def __call__(self):
	> gdb.write(self.message)
	>
	>class MyThread1 (threading.Thread):
	> def run (self):
	> gdb.post_event(Writer("Hello "))
	>
	>class MyThread2 (threading.Thread):
	> def run (self):
	> gdb.post_event(Writer("World\n"))
	>
	>MyThread1().start()
	>MyThread2().start()
	>end
	(gdb) Hello World
	</pre></div>
	</dd></dl>

	<a name="index-gdb_002ewrite"></a>
	<dl>
	<dt><a name="index-gdb_002ewrite-1"></a>Function: <strong>gdb.write</strong> <em>(string <span class="roman">[</span>, stream])</em></dt>
	<dd><p>Print a string to <small>GDB</small>’s paginated output stream. The
	optional <var>stream</var> determines the stream to print to. The default
	stream is <small>GDB</small>’s standard output stream. Possible stream
	values are:
	</p>
	<dl compact="compact">
	<dd><a name="index-STDOUT"></a>
	<a name="index-gdb_002eSTDOUT"></a>
	</dd>
	<dt><code>gdb.STDOUT</code></dt>
	<dd><p><small>GDB</small>’s standard output stream.
	</p>
	<a name="index-STDERR"></a>
	<a name="index-gdb_002eSTDERR"></a>
	</dd>
	<dt><code>gdb.STDERR</code></dt>
	<dd><p><small>GDB</small>’s standard error stream.
	</p>
	<a name="index-STDLOG"></a>
	<a name="index-gdb_002eSTDLOG"></a>
	</dd>
	<dt><code>gdb.STDLOG</code></dt>
	<dd><p><small>GDB</small>’s log stream (see <a href="Logging-Output.html#Logging-Output">Logging Output</a>).
	</p></dd>
	</dl>

	<p>Writing to <code>sys.stdout</code> or <code>sys.stderr</code> will automatically
	call this function and will automatically direct the output to the
	relevant stream.
	</p></dd></dl>

	<a name="index-gdb_002eflush"></a>
	<dl>
	<dt><a name="index-gdb_002eflush-1"></a>Function: <strong>gdb.flush</strong> <em>()</em></dt>
	<dd><p>Flush the buffer of a <small>GDB</small> paginated stream so that the
	contents are displayed immediately. <small>GDB</small> will flush the
	contents of a stream automatically when it encounters a newline in the
	buffer. The optional <var>stream</var> determines the stream to flush. The
	default stream is <small>GDB</small>’s standard output stream. Possible
	stream values are:
	</p>
	<dl compact="compact">
	<dd><a name="index-STDOUT-1"></a>
	<a name="index-gdb_002eSTDOUT-1"></a>
	</dd>
	<dt><code>gdb.STDOUT</code></dt>
	<dd><p><small>GDB</small>’s standard output stream.
	</p>
	<a name="index-STDERR-1"></a>
	<a name="index-gdb_002eSTDERR-1"></a>
	</dd>
	<dt><code>gdb.STDERR</code></dt>
	<dd><p><small>GDB</small>’s standard error stream.
	</p>
	<a name="index-STDLOG-1"></a>
	<a name="index-gdb_002eSTDLOG-1"></a>
	</dd>
	<dt><code>gdb.STDLOG</code></dt>
	<dd><p><small>GDB</small>’s log stream (see <a href="Logging-Output.html#Logging-Output">Logging Output</a>).
	</p>
	</dd>
	</dl>

	<p>Flushing <code>sys.stdout</code> or <code>sys.stderr</code> will automatically
	call this function for the relevant stream.
	</p></dd></dl>

	<a name="index-gdb_002etarget_005fcharset"></a>
	<dl>
	<dt><a name="index-gdb_002etarget_005fcharset-1"></a>Function: <strong>gdb.target_charset</strong> <em>()</em></dt>
	<dd><p>Return the name of the current target character set (see <a href="Character-Sets.html#Character-Sets">Character Sets</a>). This differs from <code>gdb.parameter('target-charset')</code> in
	that ‘<samp>auto</samp>’ is never returned.
	</p></dd></dl>

	<a name="index-gdb_002etarget_005fwide_005fcharset"></a>
	<dl>
	<dt><a name="index-gdb_002etarget_005fwide_005fcharset-1"></a>Function: <strong>gdb.target_wide_charset</strong> <em>()</em></dt>
	<dd><p>Return the name of the current target wide character set
	(see <a href="Character-Sets.html#Character-Sets">Character Sets</a>). This differs from
	<code>gdb.parameter('target-wide-charset')</code> in that ‘<samp>auto</samp>’ is
	never returned.
	</p></dd></dl>

	<a name="index-gdb_002esolib_005fname"></a>
	<dl>
	<dt><a name="index-gdb_002esolib_005fname-1"></a>Function: <strong>gdb.solib_name</strong> <em>(address)</em></dt>
	<dd><p>Return the name of the shared library holding the given <var>address</var>
	as a string, or <code>None</code>.
	</p></dd></dl>

	<a name="index-gdb_002edecode_005fline"></a>
	<dl>
	<dt><a name="index-gdb_002edecode_005fline-1"></a>Function: <strong>gdb.decode_line</strong> <em><span class="roman">[</span>expression<span class="roman">]</span></em></dt>
	<dd><p>Return locations of the line specified by <var>expression</var>, or of the
	current line if no argument was given. This function returns a Python
	tuple containing two elements. The first element contains a string
	holding any unparsed section of <var>expression</var> (or <code>None</code> if
	the expression has been fully parsed). The second element contains
	either <code>None</code> or another tuple that contains all the locations
	that match the expression represented as <code>gdb.Symtab_and_line</code>
	objects (see <a href="Symbol-Tables-In-Python.html#Symbol-Tables-In-Python">Symbol Tables In Python</a>). If <var>expression</var> is
	provided, it is decoded the way that <small>GDB</small>’s inbuilt
	<code>break</code> or <code>edit</code> commands do (see <a href="Specify-Location.html#Specify-Location">Specify Location</a>).
	</p></dd></dl>

	<dl>
	<dt><a name="index-gdb_002eprompt_005fhook"></a>Function: <strong>gdb.prompt_hook</strong> <em>(current_prompt)</em></dt>
	<dd><a name="prompt_005fhook"></a>
	<p>If <var>prompt_hook</var> is callable, <small>GDB</small> will call the method
	assigned to this operation before a prompt is displayed by
	<small>GDB</small>.
	</p>
	<p>The parameter <code>current_prompt</code> contains the current <small>GDB</small>
	prompt. This method must return a Python string, or <code>None</code>. If
	a string is returned, the <small>GDB</small> prompt will be set to that
	string. If <code>None</code> is returned, <small>GDB</small> will continue to use
	the current prompt.
	</p>
	<p>Some prompts cannot be substituted in <small>GDB</small>. Secondary prompts
	such as those used by readline for command input, and annotation
	related prompts are prohibited from being changed.
	</p></dd></dl>

	<hr>
	<div class="header">
	<p>
	Next: <a href="Exception-Handling.html#Exception-Handling" accesskey="n" rel="next">Exception Handling</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>
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