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<title>Debugging with GDB: system</title>
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<a name="system"></a>
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Previous: <a href="isatty.html#isatty" accesskey="p" rel="prev">isatty</a>, Up: <a href="List-of-Supported-Calls.html#List-of-Supported-Calls" accesskey="u" rel="up">List of Supported Calls</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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<a name="system-1"></a>
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<h4 class="unnumberedsubsubsec">system</h4>
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<a name="index-system_002c-file_002di_002fo-system-call"></a>
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<dl compact="compact">
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<dt>Synopsis:</dt>
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<dd><div class="smallexample">
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<pre class="smallexample">int system(const char *command);
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</pre></div>
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</dd>
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<dt>Request:</dt>
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<dd><p>‘<samp>Fsystem,<var>commandptr</var>/<var>len</var></samp>’
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</p>
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</dd>
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<dt>Return value:</dt>
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<dd><p>If <var>len</var> is zero, the return value indicates whether a shell is
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available. A zero return value indicates a shell is not available.
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For non-zero <var>len</var>, the value returned is -1 on error and the
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return status of the command otherwise. Only the exit status of the
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command is returned, which is extracted from the host’s <code>system</code>
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return value by calling <code>WEXITSTATUS(retval)</code>. In case
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<samp>/bin/sh</samp> could not be executed, 127 is returned.
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</p>
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</dd>
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<dt>Errors:</dt>
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<dd>
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<dl compact="compact">
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<dt><code>EINTR</code></dt>
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<dd><p>The call was interrupted by the user.
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</p></dd>
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</dl>
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</dd>
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</dl>
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<p><small>GDB</small> takes over the full task of calling the necessary host calls
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to perform the <code>system</code> call. The return value of <code>system</code> on
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the host is simplified before it’s returned
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to the target. Any termination signal information from the child process
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is discarded, and the return value consists
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entirely of the exit status of the called command.
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</p>
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<p>Due to security concerns, the <code>system</code> call is by default refused
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by <small>GDB</small>. The user has to allow this call explicitly with the
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<code>set remote system-call-allowed 1</code> command.
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</p>
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<dl compact="compact">
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<dt><code>set remote system-call-allowed</code></dt>
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<dd><a name="index-set-remote-system_002dcall_002dallowed"></a>
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<p>Control whether to allow the <code>system</code> calls in the File I/O
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protocol for the remote target. The default is zero (disabled).
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</p>
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</dd>
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<dt><code>show remote system-call-allowed</code></dt>
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<dd><a name="index-show-remote-system_002dcall_002dallowed"></a>
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<p>Show whether the <code>system</code> calls are allowed in the File I/O
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protocol.
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</p></dd>
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</dl>
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