📄 signal.html
字号:
<!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) 2001-2003 The Open Group, All Rights Reserved --><title>signal</title></head><body bgcolor="white"><script type="text/javascript" language="JavaScript" src="../jscript/codes.js"></script><basefont size="3"> <a name="signal"></a> <a name="tag_03_690"></a><!-- signal --> <!--header start--><center><font size="2">The Open Group Base Specifications Issue 6<br>IEEE Std 1003.1, 2003 Edition<br>Copyright © 2001-2003 The IEEE and The Open Group, All Rights reserved.</font></center><!--header end--><hr size="2" noshade><h4><a name="tag_03_690_01"></a>NAME</h4><blockquote>signal - signal management</blockquote><h4><a name="tag_03_690_02"></a>SYNOPSIS</h4><blockquote class="synopsis"><p><code><tt>#include <<a href="../basedefs/signal.h.html">signal.h</a>><br><br> void (*signal(int</tt> <i>sig</i><tt>, void (*</tt><i>func</i><tt>)(int)))(int);<br></tt></code></p></blockquote><h4><a name="tag_03_690_03"></a>DESCRIPTION</h4><blockquote><div class="box"><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]"border="0"> The functionality described on this reference page is aligned with the ISO C standard. Any conflict between therequirements described here and the ISO C standard is unintentional. This volume of IEEE Std 1003.1-2001 defers tothe ISO C standard. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></div><p><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> Useof this function is unspecified in a multi-threaded process. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></p><p>The <i>signal</i>() function chooses one of three ways in which receipt of the signal number <i>sig</i> is to be subsequentlyhandled. If the value of <i>func</i> is SIG_DFL, default handling for that signal shall occur. If the value of <i>func</i> isSIG_IGN, the signal shall be ignored. Otherwise, the application shall ensure that <i>func</i> points to a function to be calledwhen that signal occurs. An invocation of such a function because of a signal, or (recursively) of any further functions called bythat invocation (other than functions in the standard library), is called a "signal handler".</p><p>When a signal occurs, and <i>func</i> points to a function, it is implementation-defined whether the equivalent of a:</p><pre><tt>signal(</tt><i>sig</i><tt>, SIG_DFL);</tt></pre><p>is executed or the implementation prevents some implementation-defined set of signals (at least including <i>sig</i>) fromoccurring until the current signal handling has completed. (If the value of <i>sig</i> is SIGILL, the implementation mayalternatively define that no action is taken.) Next the equivalent of:</p><pre><tt>(*func)(sig);</tt></pre><p>is executed. If and when the function returns, if the value of <i>sig</i> was SIGFPE, SIGILL, or SIGSEGV or any otherimplementation-defined value corresponding to a computational exception, the behavior is undefined. Otherwise, the program shallresume execution at the point it was interrupted. If the signal occurs as the result of calling the <a href="../functions/abort.html"><i>abort</i>()</a>, <a href="../functions/raise.html"><i>raise</i>()</a>, <sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> <a href="../functions/kill.html"><i>kill</i>()</a>, <a href="../functions/pthread_kill.html"><i>pthread_kill</i>()</a>, or <a href="../functions/sigqueue.html"><i>sigqueue</i>()</a> <img src="../images/opt-end.gif" alt="[Option End]" border="0"> function, thesignal handler shall not call the <a href="../functions/raise.html"><i>raise</i>()</a> function.</p><p>If the signal occurs other than as the result of calling <a href="../functions/abort.html"><i>abort</i>()</a>, <a href="../functions/raise.html"><i>raise</i>()</a>, <sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> <a href="../functions/kill.html"><i>kill</i>()</a>, <a href="../functions/pthread_kill.html"><i>pthread_kill</i>()</a>, or <a href="../functions/sigqueue.html"><i>sigqueue</i>()</a>, <imgsrc="../images/opt-end.gif" alt="[Option End]" border="0"> the behavior is undefined if the signal handler refers to anyobject with static storage duration other than by assigning a value to an object declared as volatile <b>sig_atomic_t</b>, or ifthe signal handler calls any function in the standard library other than one of the functions listed in <a href="xsh_chap02_04.html#tag_02_04"><i>Signal Concepts</i></a> . Furthermore, if such a call fails, the value of <i>errno</i> isunspecified.</p><p>At program start-up, the equivalent of:</p><pre><tt>signal(</tt><i>sig</i><tt>, SIG_IGN);</tt></pre><p>is executed for some signals, and the equivalent of:</p><pre><tt>signal(</tt><i>sig</i><tt>, SIG_DFL);</tt></pre><p>is executed for all other signals <sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif"alt="[Option Start]" border="0"> (see <i><a href="../functions/exec.html">exec</a></i>). <img src="../images/opt-end.gif"alt="[Option End]" border="0"></p></blockquote><h4><a name="tag_03_690_04"></a>RETURN VALUE</h4><blockquote><p>If the request can be honored, <i>signal</i>() shall return the value of <i>func</i> for the most recent call to <i>signal</i>()for the specified signal <i>sig</i>. Otherwise, SIG_ERR shall be returned and a positive value shall be stored in <i>errno</i>.</p></blockquote><h4><a name="tag_03_690_05"></a>ERRORS</h4><blockquote><p>The <i>signal</i>() function shall fail if:</p><dl compact><dt>[EINVAL]</dt><dd><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">The <i>sig</i> argument is not a valid signal number or an attempt is made to catch a signal that cannot be caught or ignore asignal that cannot be ignored. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></dd></dl><p>The <i>signal</i>() function may fail if:</p><dl compact><dt>[EINVAL]</dt><dd><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> Anattempt was made to set the action to SIG_DFL for a signal that cannot be caught or ignored (or both). <img src="../images/opt-end.gif" alt="[Option End]" border="0"></dd></dl></blockquote><hr><div class="box"><em>The following sections are informative.</em></div><h4><a name="tag_03_690_06"></a>EXAMPLES</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_690_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>signal</i>().</p></blockquote><h4><a name="tag_03_690_08"></a>RATIONALE</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_690_09"></a>FUTURE DIRECTIONS</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_690_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="sigsuspend.html"><i>sigsuspend</i>()</a> , <a href="waitid.html"><i>waitid</i>()</a> , the Base Definitions volume of IEEE Std 1003.1-2001, <a href="../basedefs/signal.h.html"><i><signal.h></i></a></p></blockquote><h4><a name="tag_03_690_11"></a>CHANGE HISTORY</h4><blockquote><p>First released in Issue 1. Derived from Issue 1 of the SVID.</p></blockquote><h4><a name="tag_03_690_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 <a href="../functions/sigpause.html"><i>sigpause</i>()</a> function restores theprocess' signal mask to its original state before returning.</p><p>The RETURN VALUE section is updated to indicate that the <a href="../functions/sigpause.html"><i>sigpause</i>()</a> functionsuspends execution of the process until a signal is received, whereupon it returns -1 and sets <i>errno</i> to [EINTR].</p></blockquote><h4><a name="tag_03_690_13"></a>Issue 6</h4><blockquote><p>Extensions beyond the ISO C standard are marked.</p><p>The DESCRIPTION is updated to avoid use of the term "must" for application requirements.</p><p>The DESCRIPTION is updated for alignment with the ISO/IEC 9899:1999 standard.</p><p>References to the <i>wait3</i>() function are removed.</p><p>The <a href="../functions/sighold.html"><i>sighold</i>()</a>, <a href="../functions/sigignore.html"><i>sigignore</i>()</a>, <ahref="../functions/sigrelse.html"><i>sigrelse</i>()</a>, and <a href="../functions/sigset.html"><i>sigset</i>()</a> functions aresplit out onto their own reference page.</p></blockquote><div class="box"><em>End of informative text.</em></div><hr><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
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -