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17<title>Debugging with GDB: Shell Commands</title>
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64<a name="Shell-Commands"></a>
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66<p>
67Next: <a href="Logging-Output.html#Logging-Output" accesskey="n" rel="next">Logging Output</a>, Previous: <a href="Quitting-GDB.html#Quitting-GDB" accesskey="p" rel="previous">Quitting GDB</a>, Up: <a href="Invocation.html#Invocation" accesskey="u" rel="up">Invocation</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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70<a name="Shell-Commands-1"></a>
71<h3 class="section">2.3 Shell Commands</h3>
72
73<p>If you need to execute occasional shell commands during your
74debugging session, there is no need to leave or suspend <small>GDB</small>; you can
75just use the <code>shell</code> command.
76</p>
77<dl compact="compact">
78<dd><a name="index-shell"></a>
79<a name="index-_0021"></a>
80<a name="index-shell-escape"></a>
81</dd>
82<dt><code>shell <var>command-string</var></code></dt>
83<dt><code>!<var>command-string</var></code></dt>
84<dd><p>Invoke a standard shell to execute <var>command-string</var>.
85Note that no space is needed between <code>!</code> and <var>command-string</var>.
86On GNU and Unix systems, the environment variable <code>SHELL</code>, if it
87exists, determines which shell to run.  Otherwise <small>GDB</small> uses
88the default shell (<samp>/bin/sh</samp> on GNU and Unix systems,
89<samp>cmd.exe</samp> on MS-Windows, <samp>COMMAND.COM</samp> on MS-DOS, etc.).
90</p></dd>
91</dl>
92
93<p>The utility <code>make</code> is often needed in development environments.
94You do not have to use the <code>shell</code> command for this purpose in
95<small>GDB</small>:
96</p>
97<dl compact="compact">
98<dd><a name="index-make"></a>
99<a name="index-calling-make"></a>
100</dd>
101<dt><code>make <var>make-args</var></code></dt>
102<dd><p>Execute the <code>make</code> program with the specified
103arguments.  This is equivalent to &lsquo;<samp>shell make <var>make-args</var></samp>&rsquo;.
104</p></dd>
105</dl>
106
107<dl compact="compact">
108<dd><a name="index-pipe"></a>
109<a name="index-_007c"></a>
110<a name="index-send-the-output-of-a-gdb-command-to-a-shell-command"></a>
111<a name="pipe"></a></dd>
112<dt><code>pipe [<var>command</var>] | <var>shell_command</var></code></dt>
113<dt><code>| [<var>command</var>] | <var>shell_command</var></code></dt>
114<dt><code>pipe -d <var>delim</var> <var>command</var> <var>delim</var> <var>shell_command</var></code></dt>
115<dt><code>| -d <var>delim</var> <var>command</var> <var>delim</var> <var>shell_command</var></code></dt>
116<dd><p>Executes <var>command</var> and sends its output to <var>shell_command</var>.
117Note that no space is needed around <code>|</code>.
118If no <var>command</var> is provided, the last command executed is repeated.
119</p>
120<p>In case the <var>command</var> contains a <code>|</code>, the option <code>-d <var>delim</var></code>
121can be used to specify an alternate delimiter string <var>delim</var> that separates
122the <var>command</var> from the <var>shell_command</var>.
123</p>
124<p>Example:
125</p><div class="smallexample">
126<pre class="smallexample">(gdb) p var
127$1 = {
128  black = 144,
129  red = 233,
130  green = 377,
131  blue = 610,
132  white = 987
133}
134</pre><pre class="smallexample">(gdb) pipe p var|wc
135      7      19      80
136(gdb) |p var|wc -l
1377
138</pre><pre class="smallexample">(gdb) p /x var
139$4 = {
140  black = 0x90,
141  red = 0xe9,
142  green = 0x179,
143  blue = 0x262,
144  white = 0x3db
145}
146(gdb) ||grep red
147  red =&gt; 0xe9,
148</pre><pre class="smallexample">(gdb) | -d ! echo this contains a | char\n ! sed -e 's/|/PIPE/'
149this contains a PIPE char
150(gdb) | -d xxx echo this contains a | char!\n xxx sed -e 's/|/PIPE/'
151this contains a PIPE char!
152(gdb)
153</pre></div>
154</dd>
155</dl>
156
157<p>The convenience variables <code>$_shell_exitcode</code> and <code>$_shell_exitsignal</code>
158can be used to examine the exit status of the last shell command launched
159by <code>shell</code>, <code>make</code>, <code>pipe</code> and <code>|</code>.
160See <a href="Convenience-Vars.html#Convenience-Vars">Convenience Variables</a>.
161</p>
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