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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html> <head> <title>Get a semaphore id</title> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> </head> <body><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.sem-acquire.html">sem_acquire</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.sem-release.html">sem_release</a></div> <div class="up"><a href="ref.sem.html">Semaphore Functions</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div><hr /><div id="function.sem-get" class="refentry"> <div class="refnamediv"> <h1 class="refname">sem_get</h1> <p class="verinfo">(PHP 4, PHP 5)</p><p class="refpurpose"><span class="refname">sem_get</span> — <span class="dc-title">Get a semaphore id</span></p> </div> <div class="refsect1 description"> <h3 class="title">Description</h3> <div class="methodsynopsis dc-description"> <span class="type">resource</span> <span class="methodname"><b><b>sem_get</b></b></span> ( <span class="methodparam"><span class="type">int</span> <tt class="parameter">$key</tt></span> [, <span class="methodparam"><span class="type">int</span> <tt class="parameter">$max_acquire</tt></span> [, <span class="methodparam"><span class="type">int</span> <tt class="parameter">$perm</tt></span> [, <span class="methodparam"><span class="type">int</span> <tt class="parameter">$auto_release</tt></span> ]]] )</div> <p class="para rdfs-comment"> <b>sem_get()</b> returns an id that can be used to access the System V semaphore with the given <i><tt class="parameter">key</tt></i>. </p> <p class="para"> A second call to <b>sem_get()</b> for the same key will return a different semaphore identifier, but both identifiers access the same underlying semaphore. </p> </div> <div class="refsect1 parameters"> <h3 class="title">Parameters</h3> <p class="para"> <dl> <dt> <span class="term"><i><tt class="parameter">key</tt></i></span> <dd> <p class="para"> </p> </dd> </dt> <dt> <span class="term"><i><tt class="parameter">max_acquire</tt></i></span> <dd> <p class="para"> The number of processes that can acquire the semaphore simultaneously is set to <i><tt class="parameter">max_acquire</tt></i> (defaults to 1). </p> </dd> </dt> <dt> <span class="term"><i><tt class="parameter">perm</tt></i></span> <dd> <p class="para"> The semaphore permissions. Defaults to 0666. Actually this value is set only if the process finds it is the only process currently attached to the semaphore. </p> </dd> </dt> <dt> <span class="term"><i><tt class="parameter">auto_release</tt></i></span> <dd> <p class="para"> Specifies if the semaphore should be automatically released on request shutdown. </p> </dd> </dt> </dl> </p> </div> <div class="refsect1 returnvalues"> <h3 class="title">Return Values</h3> <p class="para"> Returns a positive semaphore identifier on success, or <b><tt>FALSE</tt></b> on error. </p> </div> <div class="refsect1 changelog"> <h3 class="title">ChangeLog</h3> <p class="para"> <table class="informaltable"> <colgroup> <thead valign="middle"> <tr valign="middle"> <th colspan="1">Version</th> <th colspan="1">Description</th> </tr> </thead> <tbody valign="middle" class="tbody"> <tr valign="middle"> <td colspan="1" rowspan="1" align="left">4.3.0</td> <td colspan="1" rowspan="1" align="left"> The <i><tt class="parameter">auto_release</tt></i> parameter was added. </td> </tr> </tbody> </colgroup> </table> </p> </div> <div class="refsect1 seealso"> <h3 class="title">See Also</h3> <p class="para"> <ul class="simplelist"> <li class="member"><a href="function.sem-acquire.html" class="function" rel="rdfs-seeAlso">sem_acquire()</a></li> <li class="member"><a href="function.sem-release.html" class="function" rel="rdfs-seeAlso">sem_release()</a></li> <li class="member"><a href="function.ftok.html" class="function" rel="rdfs-seeAlso">ftok()</a></li> </ul> </p> </div> </div><hr /><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.sem-acquire.html">sem_acquire</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.sem-release.html">sem_release</a></div> <div class="up"><a href="ref.sem.html">Semaphore Functions</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div></body></html>⌨️ 快捷键说明
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