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<a name="Shell-Commands"></a>
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<hr>
<a name="Shell-Commands-1"></a>
<h3 class="section">2.3 Shell Commands</h3>

<p>If you need to execute occasional shell commands during your
debugging session, there is no need to leave or suspend <small>GDB</small>; you can
just use the <code>shell</code> command.
</p>
<dl compact="compact">
<dd><a name="index-shell"></a>
<a name="index-_0021"></a>
<a name="index-shell-escape"></a>
</dd>
<dt><code>shell <var>command-string</var></code></dt>
<dt><code>!<var>command-string</var></code></dt>
<dd><p>Invoke a standard shell to execute <var>command-string</var>.
Note that no space is needed between <code>!</code> and <var>command-string</var>.
On GNU and Unix systems, the environment variable <code>SHELL</code>, if it
exists, determines which shell to run.  Otherwise <small>GDB</small> uses
the default shell (<samp>/bin/sh</samp> on GNU and Unix systems,
<samp>cmd.exe</samp> on MS-Windows, <samp>COMMAND.COM</samp> on MS-DOS, etc.).
</p></dd>
</dl>

<p>The utility <code>make</code> is often needed in development environments.
You do not have to use the <code>shell</code> command for this purpose in
<small>GDB</small>:
</p>
<dl compact="compact">
<dd><a name="index-make"></a>
<a name="index-calling-make"></a>
</dd>
<dt><code>make <var>make-args</var></code></dt>
<dd><p>Execute the <code>make</code> program with the specified
arguments.  This is equivalent to &lsquo;<samp>shell make <var>make-args</var></samp>&rsquo;.
</p></dd>
</dl>

<dl compact="compact">
<dd><a name="index-pipe"></a>
<a name="index-_007c"></a>
<a name="index-send-the-output-of-a-gdb-command-to-a-shell-command"></a>
<a name="pipe"></a></dd>
<dt><code>pipe [<var>command</var>] | <var>shell_command</var></code></dt>
<dt><code>| [<var>command</var>] | <var>shell_command</var></code></dt>
<dt><code>pipe -d <var>delim</var> <var>command</var> <var>delim</var> <var>shell_command</var></code></dt>
<dt><code>| -d <var>delim</var> <var>command</var> <var>delim</var> <var>shell_command</var></code></dt>
<dd><p>Executes <var>command</var> and sends its output to <var>shell_command</var>.
Note that no space is needed around <code>|</code>.
If no <var>command</var> is provided, the last command executed is repeated.
</p>
<p>In case the <var>command</var> contains a <code>|</code>, the option <code>-d <var>delim</var></code>
can be used to specify an alternate delimiter string <var>delim</var> that separates
the <var>command</var> from the <var>shell_command</var>.
</p>
<p>Example:
</p><div class="smallexample">
<pre class="smallexample">(gdb) p var
$1 = {
  black = 144,
  red = 233,
  green = 377,
  blue = 610,
  white = 987
}
</pre><pre class="smallexample">(gdb) pipe p var|wc
      7      19      80
(gdb) |p var|wc -l
7
</pre><pre class="smallexample">(gdb) p /x var
$4 = {
  black = 0x90,
  red = 0xe9,
  green = 0x179,
  blue = 0x262,
  white = 0x3db
}
(gdb) ||grep red
  red =&gt; 0xe9,
</pre><pre class="smallexample">(gdb) | -d ! echo this contains a | char\n ! sed -e 's/|/PIPE/'
this contains a PIPE char
(gdb) | -d xxx echo this contains a | char!\n xxx sed -e 's/|/PIPE/'
this contains a PIPE char!
(gdb)
</pre></div>
</dd>
</dl>

<p>The convenience variables <code>$_shell_exitcode</code> and <code>$_shell_exitsignal</code>
can be used to examine the exit status of the last shell command launched
by <code>shell</code>, <code>make</code>, <code>pipe</code> and <code>|</code>.
See <a href="Convenience-Vars.html#Convenience-Vars">Convenience Variables</a>.
</p>
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