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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>sighold</title></head><body bgcolor="white"><script type="text/javascript" language="JavaScript" src="../jscript/codes.js"></script><basefont size="3"> <a name="sighold"></a> <a name="tag_03_686"></a><!-- sighold --> <!--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_686_01"></a>NAME</h4><blockquote>sighold, sigignore, sigpause, sigrelse, sigset - signal management</blockquote><h4><a name="tag_03_686_02"></a>SYNOPSIS</h4><blockquote class="synopsis"><div class="box"><code><tt><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> #include <<a href="../basedefs/signal.h.html">signal.h</a>><br><br> int sighold(int</tt> <i>sig</i><tt>);<br> int sigignore(int</tt> <i>sig</i><tt>);<br> int sigpause(int</tt> <i>sig</i><tt>);<br> int sigrelse(int</tt> <i>sig</i><tt>);<br> void (*sigset(int</tt> <i>sig</i><tt>, void (*</tt><i>disp</i><tt>)(int)))(int); <img src="../images/opt-end.gif" alt="[Option End]" border="0"></tt></code></div><tt><br></tt></blockquote><h4><a name="tag_03_686_03"></a>DESCRIPTION</h4><blockquote><p>Use of any of these functions is unspecified in a multi-threaded process.</p><p>The <i>sighold</i>(), <i>sigignore</i>(), <i>sigpause</i>(), <i>sigrelse</i>(), and <i>sigset</i>() functions provide simplifiedsignal management.</p><p>The <i>sigset</i>() function shall modify signal dispositions. The <i>sig</i> argument specifies the signal, which may be anysignal except SIGKILL and SIGSTOP. The <i>disp</i> argument specifies the signal's disposition, which may be SIG_DFL, SIG_IGN, orthe address of a signal handler. If <i>sigset</i>() is used, and <i>disp</i> is the address of a signal handler, the system shalladd <i>sig</i> to the calling process' signal mask before executing the signal handler; when the signal handler returns, the systemshall restore the calling process' signal mask to its state prior to the delivery of the signal. In addition, if <i>sigset</i>() isused, and <i>disp</i> is equal to SIG_HOLD, <i>sig</i> shall be added to the calling process' signal mask and <i>sig</i>'sdisposition shall remain unchanged. If <i>sigset</i>() is used, and <i>disp</i> is not equal to SIG_HOLD, <i>sig</i> shall beremoved from the calling process' signal mask.</p><p>The <i>sighold</i>() function shall add <i>sig</i> to the calling process' signal mask.</p><p>The <i>sigrelse</i>() function shall remove <i>sig</i> from the calling process' signal mask.</p><p>The <i>sigignore</i>() function shall set the disposition of <i>sig</i> to SIG_IGN.</p><p>The <i>sigpause</i>() function shall remove <i>sig</i> from the calling process' signal mask and suspend the calling processuntil a signal is received. The <i>sigpause</i>() function shall restore the process' signal mask to its original state beforereturning.</p><p>If the action for the SIGCHLD signal is set to SIG_IGN, child processes of the calling processes shall not be transformed intozombie processes when they terminate. If the calling process subsequently waits for its children, and the process has nounwaited-for children that were transformed into zombie processes, it shall block until all of its children terminate, and <a href="../functions/wait.html"><i>wait</i>()</a>, <a href="../functions/waitid.html"><i>waitid</i>()</a>, and <a href="../functions/waitpid.html"><i>waitpid</i>()</a> shall fail and set <i>errno</i> to [ECHILD].</p></blockquote><h4><a name="tag_03_686_04"></a>RETURN VALUE</h4><blockquote><p>Upon successful completion, <i>sigset</i>() shall return SIG_HOLD if the signal had been blocked and the signal's previousdisposition if it had not been blocked. Otherwise, SIG_ERR shall be returned and <i>errno</i> set to indicate the error.</p><p>The <i>sigpause</i>() function shall suspend execution of the thread until a signal is received, whereupon it shall return -1and set <i>errno</i> to [EINTR].</p><p>For all other functions, upon successful completion, 0 shall be returned. Otherwise, -1 shall be returned and <i>errno</i> setto indicate the error.</p></blockquote><h4><a name="tag_03_686_05"></a>ERRORS</h4><blockquote><p>These functions shall fail if:</p><dl compact><dt>[EINVAL]</dt><dd>The <i>sig</i> argument is an illegal signal number.</dd></dl><p>The <i>sigset</i>() and <i>sigignore</i>() functions shall fail if:</p><dl compact><dt>[EINVAL]</dt><dd>An attempt is made to catch a signal that cannot be caught, or to ignore a signal that cannot be ignored.</dd></dl></blockquote><hr><div class="box"><em>The following sections are informative.</em></div><h4><a name="tag_03_686_06"></a>EXAMPLES</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_686_07"></a>APPLICATION USAGE</h4><blockquote><p>The <a href="../functions/sigaction.html"><i>sigaction</i>()</a> function provides a more comprehensive and reliable mechanismfor controlling signals; new applications should use <a href="../functions/sigaction.html"><i>sigaction</i>()</a> rather than<i>sigset</i>().</p><p>The <i>sighold</i>() function, in conjunction with <i>sigrelse</i>() or <i>sigpause</i>(), may be used to establish criticalregions of code that require the delivery of a signal to be temporarily deferred.</p><p>The <a href="../functions/sigsuspend.html"><i>sigsuspend</i>()</a> function should be used in preference to <i>sigpause</i>()for broader portability.</p></blockquote><h4><a name="tag_03_686_08"></a>RATIONALE</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_686_09"></a>FUTURE DIRECTIONS</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_686_10"></a>SEE ALSO</h4><blockquote><p><a href="xsh_chap02_04.html#tag_02_04"><i>Signal Concepts</i></a>, <a href="exec.html"><i><a href="../functions/exec.html">exec</a></i>()</a>, <a href="pause.html"><i>pause</i>()</a>, <a href="sigaction.html"><i>sigaction</i>()</a>, <a href="signal.html"><i>signal</i>()</a>, <a href="sigsuspend.html"><i>sigsuspend</i>()</a>, <a href="waitid.html"><i>waitid</i>()</a>, the Base Definitions volume ofIEEE Std 1003.1-2001, <a href="../basedefs/signal.h.html"><i><signal.h></i></a></p></blockquote><h4><a name="tag_03_686_11"></a>CHANGE HISTORY</h4><blockquote><p>First released in Issue 4, Version 2.</p></blockquote><h4><a name="tag_03_686_12"></a>Issue 5</h4><blockquote><p>Moved from X/OPEN UNIX extension to BASE.</p><p>The DESCRIPTION is updated to indicate that the <i>sigpause</i>() function restores the process' signal mask to its originalstate before returning.</p><p>The RETURN VALUE section is updated to indicate that the <i>sigpause</i>() function suspends execution of the process until asignal is received, whereupon it returns -1 and sets <i>errno</i> to [EINTR].</p></blockquote><h4><a name="tag_03_686_13"></a>Issue 6</h4><blockquote><p>The DESCRIPTION is updated to avoid use of the term "must" for application requirements.</p><p>References to the <i>wait3</i>() function are removed.</p><p>The XSI functions are split out into their own reference page.</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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