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| <h4 class="subsection">25.6.5 Termination Internals</h4> |
| |
| <p>The <code>_exit</code> function is the primitive used for process termination |
| by <code>exit</code>. It is declared in the header file <samp><span class="file">unistd.h</span></samp>. |
| <a name="index-unistd_002eh-3144"></a> |
| <!-- unistd.h --> |
| <!-- POSIX.1 --> |
| |
| <div class="defun"> |
| — Function: void <b>_exit</b> (<var>int status</var>)<var><a name="index-g_t_005fexit-3145"></a></var><br> |
| <blockquote><p>The <code>_exit</code> function is the primitive for causing a process to |
| terminate with status <var>status</var>. Calling this function does not |
| execute cleanup functions registered with <code>atexit</code> or |
| <code>on_exit</code>. |
| </p></blockquote></div> |
| |
| <!-- stdlib.h --> |
| <!-- ISO --> |
| <div class="defun"> |
| — Function: void <b>_Exit</b> (<var>int status</var>)<var><a name="index-g_t_005fExit-3146"></a></var><br> |
| <blockquote><p>The <code>_Exit</code> function is the ISO C<!-- /@w --> equivalent to <code>_exit</code>. |
| The ISO C<!-- /@w --> committee members were not sure whether the definitions of |
| <code>_exit</code> and <code>_Exit</code> were compatible so they have not used the |
| POSIX name. |
| |
| <p>This function was introduced in ISO C99<!-- /@w --> and is declared in |
| <samp><span class="file">stdlib.h</span></samp>. |
| </p></blockquote></div> |
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| <p>When a process terminates for any reason—either because the program |
| terminates, or as a result of a signal—the |
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| <li>A process exit status is saved to be reported back to the parent process |
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| program exited, this status includes as its low-order 8 bits the program |
| exit status. |
| |
| <li>Any child processes of the process being terminated are assigned a new |
| parent process. (On most systems, including GNU, this is the <code>init</code> |
| process, with process ID 1.) |
| |
| <li>A <code>SIGCHLD</code> signal is sent to the parent process. |
| |
| <li>If the process is a session leader that has a controlling terminal, then |
| a <code>SIGHUP</code> signal is sent to each process in the foreground job, |
| and the controlling terminal is disassociated from that session. |
| See <a href="Job-Control.html#Job-Control">Job Control</a>. |
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| <li>If termination of a process causes a process group to become orphaned, |
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