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| <h5 class="unnumberedsubsubsec">system</h5> |
| |
| <p><a name="index-system_002c-file_002di_002fo-system-call-2515"></a> |
| <dl> |
| <dt>Synopsis:<dd> |
| <pre class="smallexample"> int system(const char *command); |
| </pre> |
| <br><dt>Request:<dd>‘<samp><span class="samp">Fsystem,</span><var>commandptr</var><span class="samp">/</span><var>len</var></samp>’ |
| |
| <br><dt>Return value:<dd>If <var>len</var> is zero, the return value indicates whether a shell is |
| available. A zero return value indicates a shell is not available. |
| For non-zero <var>len</var>, the value returned is -1 on error and the |
| return status of the command otherwise. Only the exit status of the |
| command is returned, which is extracted from the host's <code>system</code> |
| return value by calling <code>WEXITSTATUS(retval)</code>. In case |
| <samp><span class="file">/bin/sh</span></samp> could not be executed, 127 is returned. |
| |
| <br><dt>Errors:<dd> |
| <dl> |
| <dt><code>EINTR</code><dd>The call was interrupted by the user. |
| </dl> |
| |
| </dl> |
| |
| <p><span class="sc">gdb</span> takes over the full task of calling the necessary host calls |
| to perform the <code>system</code> call. The return value of <code>system</code> on |
| the host is simplified before it's returned |
| to the target. Any termination signal information from the child process |
| is discarded, and the return value consists |
| entirely of the exit status of the called command. |
| |
| <p>Due to security concerns, the <code>system</code> call is by default refused |
| by <span class="sc">gdb</span>. The user has to allow this call explicitly with the |
| <code>set remote system-call-allowed 1</code> command. |
| |
| <dl> |
| <dt><code>set remote system-call-allowed</code><dd><a name="index-set-remote-system_002dcall_002dallowed-2516"></a>Control whether to allow the <code>system</code> calls in the File I/O |
| protocol for the remote target. The default is zero (disabled). |
| |
| <br><dt><code>show remote system-call-allowed</code><dd><a name="index-show-remote-system_002dcall_002dallowed-2517"></a>Show whether the <code>system</code> calls are allowed in the File I/O |
| protocol. |
| </dl> |
| |
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