145 lines
5.1 KiB
HTML
145 lines
5.1 KiB
HTML
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<title>sem_unlink</title>
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<basefont size="3"> <a name="sem_unlink"></a> <a name="tag_03_636"></a><!-- sem_unlink -->
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<!--header start-->
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<center><font size="2">The Open Group Base Specifications Issue 6<br>
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IEEE Std 1003.1-2001<br>
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Copyright © 2001 The IEEE and The Open Group, All Rights reserved.</font></center>
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<!--header end-->
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<hr size="2" noshade>
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<h4><a name="tag_03_636_01"></a>NAME</h4>
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<blockquote>sem_unlink - remove a named semaphore (<b>REALTIME</b>)</blockquote>
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<h4><a name="tag_03_636_02"></a>SYNOPSIS</h4>
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<blockquote class="synopsis">
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<div class="box"><code><tt><sup>[<a href="javascript:open_code('SEM')">SEM</a>]</sup> <img src="../images/opt-start.gif" alt=
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"[Option Start]" border="0"> #include <<a href="../basedefs/semaphore.h.html">semaphore.h</a>><br>
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<br>
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int sem_unlink(const char *</tt><i>name</i><tt>); <img src="../images/opt-end.gif" alt="[Option End]" border="0"></tt></code></div>
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<tt><br>
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</tt></blockquote>
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<h4><a name="tag_03_636_03"></a>DESCRIPTION</h4>
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<blockquote>
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<p>The <i>sem_unlink</i>() function shall remove the semaphore named by the string <i>name</i>. If the semaphore named by
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<i>name</i> is currently referenced by other processes, then <i>sem_unlink</i>() shall have no effect on the state of the
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semaphore. If one or more processes have the semaphore open when <i>sem_unlink</i>() is called, destruction of the semaphore is
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postponed until all references to the semaphore have been destroyed by calls to <a href=
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"../functions/sem_close.html"><i>sem_close</i>()</a>, <a href="../functions/_exit.html"><i>_exit</i>()</a>, or <i><a href=
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"../functions/exec.html">exec</a></i>. Calls to <a href="../functions/sem_open.html"><i>sem_open</i>()</a> to recreate or reconnect
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to the semaphore refer to a new semaphore after <i>sem_unlink</i>() is called. The <i>sem_unlink</i>() call shall not block until
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all references have been destroyed; it shall return immediately.</p>
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</blockquote>
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<h4><a name="tag_03_636_04"></a>RETURN VALUE</h4>
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<blockquote>
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<p>Upon successful completion, the <i>sem_unlink</i>() function shall return a value of 0. Otherwise, the semaphore shall not be
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changed and the function shall return a value of -1 and set <i>errno</i> to indicate the error.</p>
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</blockquote>
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<h4><a name="tag_03_636_05"></a>ERRORS</h4>
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<blockquote>
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<p>The <i>sem_unlink</i>() function shall fail if:</p>
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<dl compact>
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<dt>[EACCES]</dt>
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<dd>Permission is denied to unlink the named semaphore.</dd>
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<dt>[ENAMETOOLONG]</dt>
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<dd>
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The length of the <i>name</i> argument exceeds {PATH_MAX} or a pathname component is longer than {NAME_MAX}.</dd>
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<dt>[ENOENT]</dt>
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<dd>The named semaphore does not exist.</dd>
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</dl>
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</blockquote>
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<hr>
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<div class="box"><em>The following sections are informative.</em></div>
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<h4><a name="tag_03_636_06"></a>EXAMPLES</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_03_636_07"></a>APPLICATION USAGE</h4>
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<blockquote>
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<p>The <i>sem_unlink</i>() function is part of the Semaphores option and need not be available on all implementations.</p>
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</blockquote>
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<h4><a name="tag_03_636_08"></a>RATIONALE</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_03_636_09"></a>FUTURE DIRECTIONS</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_03_636_10"></a>SEE ALSO</h4>
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<blockquote>
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<p><a href="semctl.html"><i>semctl</i>()</a> , <a href="semget.html"><i>semget</i>()</a> , <a href="semop.html"><i>semop</i>()</a>
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, <a href="sem_close.html"><i>sem_close</i>()</a> , <a href="sem_open.html"><i>sem_open</i>()</a> , the Base Definitions volume of
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IEEE Std 1003.1-2001, <a href="../basedefs/semaphore.h.html"><i><semaphore.h></i></a></p>
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</blockquote>
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<h4><a name="tag_03_636_11"></a>CHANGE HISTORY</h4>
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<blockquote>
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<p>First released in Issue 5. Included for alignment with the POSIX Realtime Extension.</p>
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</blockquote>
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<h4><a name="tag_03_636_12"></a>Issue 6</h4>
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<blockquote>
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<p>The <i>sem_unlink</i>() function is marked as part of the Semaphores option.<br>
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</p>
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<p>The [ENOSYS] error condition has been removed as stubs need not be provided if an implementation does not support the Semaphores
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option.</p>
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</blockquote>
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<div class="box"><em>End of informative text.</em></div>
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