sem_unlink.html
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><meta name="generator" content="HTML Tidy, see www.w3.org"><meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><link type="text/css" rel="stylesheet" href="style.css"><!-- Generated by The Open Group's rhtm tool v1.2.1 --><!-- Copyright (c) 2001-2004 IEEE and The Open Group, All Rights Reserved --><title>sem_unlink</title></head><body bgcolor="white"><script type="text/javascript" language="JavaScript" src="../jscript/codes.js"></script><basefont size="3"> <a name="sem_unlink"></a> <a name="tag_03_636"></a><!-- sem_unlink --> <!--header start--><center><font size="2">The Open Group Base Specifications Issue 6<br>IEEE Std 1003.1, 2004 Edition<br>Copyright © 2001-2004 The IEEE and The Open Group, All Rights reserved.</font></center><!--header end--><hr size="2" noshade><h4><a name="tag_03_636_01"></a>NAME</h4><blockquote>sem_unlink - remove a named semaphore (<b>REALTIME</b>)</blockquote><h4><a name="tag_03_636_02"></a>SYNOPSIS</h4><blockquote class="synopsis"><div class="box"><code><tt><sup>[<a href="javascript:open_code('SEM')">SEM</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> #include <<a href="../basedefs/semaphore.h.html">semaphore.h</a>><br><br> int sem_unlink(const char *</tt><i>name</i><tt>); <img src="../images/opt-end.gif" alt="[Option End]" border="0"></tt></code></div><tt><br></tt></blockquote><h4><a name="tag_03_636_03"></a>DESCRIPTION</h4><blockquote><p>The <i>sem_unlink</i>() function shall remove the semaphore named by the string <i>name</i>. If the semaphore named by<i>name</i> is currently referenced by other processes, then <i>sem_unlink</i>() shall have no effect on the state of thesemaphore. If one or more processes have the semaphore open when <i>sem_unlink</i>() is called, destruction of the semaphore ispostponed until all references to the semaphore have been destroyed by calls to <a href="../functions/sem_close.html"><i>sem_close</i>()</a>, <a href="../functions/_exit.html"><i>_exit</i>()</a>, or <i><a href="../functions/exec.html">exec</a></i>. Calls to <a href="../functions/sem_open.html"><i>sem_open</i>()</a> to recreate or reconnectto the semaphore refer to a new semaphore after <i>sem_unlink</i>() is called. The <i>sem_unlink</i>() call shall not block untilall references have been destroyed; it shall return immediately.</p></blockquote><h4><a name="tag_03_636_04"></a>RETURN VALUE</h4><blockquote><p>Upon successful completion, the <i>sem_unlink</i>() function shall return a value of 0. Otherwise, the semaphore shall not bechanged and the function shall return a value of -1 and set <i>errno</i> to indicate the error.</p></blockquote><h4><a name="tag_03_636_05"></a>ERRORS</h4><blockquote><p>The <i>sem_unlink</i>() function shall fail if:</p><dl compact><dt>[EACCES]</dt><dd>Permission is denied to unlink the named semaphore.</dd><dt>[ENAMETOOLONG]</dt><dd>The length of the <i>name</i> argument exceeds {PATH_MAX} or a pathname component is longer than {NAME_MAX}.</dd><dt>[ENOENT]</dt><dd>The named semaphore does not exist.</dd></dl></blockquote><hr><div class="box"><em>The following sections are informative.</em></div><h4><a name="tag_03_636_06"></a>EXAMPLES</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_636_07"></a>APPLICATION USAGE</h4><blockquote><p>The <i>sem_unlink</i>() function is part of the Semaphores option and need not be available on all implementations.</p></blockquote><h4><a name="tag_03_636_08"></a>RATIONALE</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_636_09"></a>FUTURE DIRECTIONS</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_636_10"></a>SEE ALSO</h4><blockquote><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>, <a href="sem_close.html"><i>sem_close</i>()</a>, <a href="sem_open.html"><i>sem_open</i>()</a>, the Base Definitions volume ofIEEE Std 1003.1-2001, <a href="../basedefs/semaphore.h.html"><i><semaphore.h></i></a></p></blockquote><h4><a name="tag_03_636_11"></a>CHANGE HISTORY</h4><blockquote><p>First released in Issue 5. Included for alignment with the POSIX Realtime Extension.</p></blockquote><h4><a name="tag_03_636_12"></a>Issue 6</h4><blockquote><p>The <i>sem_unlink</i>() function is marked as part of the Semaphores option.<br></p><p>The [ENOSYS] error condition has been removed as stubs need not be provided if an implementation does not support the Semaphoresoption.</p></blockquote><div class="box"><em>End of informative text.</em></div><hr size="2" noshade><center><font size="2"><!--footer start-->UNIX ® is a registered Trademark of The Open Group.<br>POSIX ® is a registered Trademark of The IEEE.<br>[ <a href="../mindex.html">Main Index</a> | <a href="../basedefs/contents.html">XBD</a> | <a href="../utilities/contents.html">XCU</a> | <a href="../functions/contents.html">XSH</a> | <a href="../xrat/contents.html">XRAT</a>]</font></center><!--footer end--><hr size="2" noshade></body></html>⌨️ 快捷键说明
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