321 lines
8.3 KiB
HTML
321 lines
8.3 KiB
HTML
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<html>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<meta name="Copyright" content="Copyright (c) 2006 by IBM Corporation">
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<title>sigsuspend()--Wait for Signal</title>
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<!-- at RCHVMW2 on 17 Feb 1999 at 11:05:09 -->
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</head>
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<body>
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<a name="Top_Of_Page"></a>
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<script type="text/javascript" language="Javascript" src="../rzahg/synch.js">
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</script>
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<h2>sigsuspend()--Wait for Signal</h2>
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<div class="box" style="width: 60%;">
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<br>
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Syntax<br>
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<pre>
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#include <signal.h>
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int sigsuspend( const sigset_t <em>*sigmask</em> );
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</pre>
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<br>
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Service Program Name: QPOSSRV1<br>
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<!-- iddvc RMBR -->
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<br>
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Default Public Authority: *USE<br>
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<!-- iddvc RMBR -->
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<br>
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Threadsafe: Yes<br>
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<!-- iddvc RMBR -->
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<br>
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</div>
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<p>The <strong>sigsuspend()</strong> function replaces the current signal mask
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of a thread with the signal set given by <em>*sigmask</em> and then suspends
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processing of the calling process. The thread does not resume running until a
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signal is delivered whose action is to call a signal-catching function, to end
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the request, or to terminate the process. (Signal sets are described in more
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detail in <a href="sigeset.htm">sigemptyset()--Initialize and Empty Signal
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Set</a>.)</p>
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<p>The signal mask indicates a set of signals that should be blocked. Such
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signals do not "wake up" the suspended function. The signals SIGStop and
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SIGKILL cannot be blocked or ignored; they are delivered to the thread
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regardless of what the <em>sigmask</em> argument specifies.</p>
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<p>If an incoming unblocked signal has an action of end the request of
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terminate the process, <strong>sigsuspend()</strong> never returns to the
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caller. If an incoming signal is handled by a signal-catching function,
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<strong>sigsuspend()</strong> returns after the signal-catching function
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returns. In this case, the signal mask of the thread is restored to whatever it
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was before <strong>sigsuspend()</strong> was called.</p>
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<br>
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<!-- Please NOTE: DO NOT DELETE THIS SECTION if this API has no authorities and locks. -->
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<!-- Instead, use the commented out coding below to indicate NONE. -->
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<h3>Authorities and Locks</h3>
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<!-- Use this if there are no authorities and locks. -->
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<p>None.</p>
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<br>
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<h3>Parameters</h3>
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<dl>
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<dt><strong><em>*sigmask</em></strong></dt>
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<dd>(Input) A pointer to a set of signals to be used to replace the current
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signal mask of the process.</dd>
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</dl>
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<br>
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<h3>Return Value</h3>
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<table cellpadding="5">
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<!-- cols="5 95" -->
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<tr>
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<td align="left" valign="top"><em>-1</em></td>
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<td align="left" valign="top"><strong>sigsuspend()</strong> was not successful.
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The <em>errno</em> variable is set to indicate the reason.</td>
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</tr>
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</table>
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<p>There is no return value to indicate successful completion.</p>
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<br>
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<h3>Error Conditions</h3>
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<p>If <strong>sigsuspend()</strong> returns, <em>errno</em> indicates the
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following:</p>
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<dl>
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<dt><em>[EINTR]</em></dt>
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<dd>
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<p>Interrupted function call.</p>
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<p>A signal was received and handled by a signal-catching function that
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returned.</p>
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</dd>
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<dt><em>[EINVAL]</em></dt>
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<dd>
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<p>The value specified for the argument is not correct.</p>
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<p>A function was passed incorrect argument values, or an operation was
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attempted on an object and the operation specified is not supported for that
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type of object.</p>
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<p>An argument value is not valid, out of range, or NULL. The signal set
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pointed to by <em>sigmask</em> contains a signal that is not within the valid
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range or a signal that is not supported.</p>
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</dd>
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<dt><em>[ENOTSIGINIT]</em></dt>
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<dd>
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<p>Process not enabled for signals.</p>
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<p>An attempt was made to call a signal function under one of the following
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conditions:</p>
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<ul>
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<li>The signal function is being called for a process that is not enabled for
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asynchronous signals.</li>
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<li>The signal function is being called when the system signal controls have
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not been initialized.</li>
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</ul>
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<br>
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</dd>
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<dt><em>[EWOULDBLOCK]</em></dt>
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<dd>
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<p>Operation would have caused the process to be suspended.</p>
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<p>The current thread state would prevent the signal function from
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completing.</p>
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</dd>
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</dl>
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<br>
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<h3>Usage Notes</h3>
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<p>The <strong>sigsuspend</strong> function enables a process for signals if
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the process is not already enabled for signals. For details, see <a href=
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"sigeset.htm">Qp0sEnableSignals()--Enable Process for Signals</a>. If the
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system has not been enabled for signals, <strong>sigsuspend()</strong> is not
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successful, and an [ENOTSIGINIT] error is returned.</p>
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<br>
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<h3>Related Information</h3>
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<ul>
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<li>The <<strong>signal.h</strong>> file (see <a href="unix13.htm">Header
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Files for UNIX-Type Functions</a>)<br>
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<br>
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</li>
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<li><a href="sigalarm.htm">alarm()</a>--Set Schedule for Alarm Signal<br>
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<br>
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</li>
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<li><a href="sigpause.htm">pause()</a>--Suspend Process Until Signal
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Received<br>
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<br>
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</li>
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<li><a href="sigdsig.htm">Qp0sDisableSignals()</a>--Disable Process for
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Signals<br>
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<br>
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</li>
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<li><a href="sigesig.htm">Qp0sEnableSignals()</a>--Enable Process for
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Signals<br>
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<br>
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</li>
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<li><a href="sigactn.htm">sigaction()</a>--Examine and Change Signal Action<br>
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<br>
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</li>
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<li><a href="sigaset.htm">sigaddset()</a>--Add Signal to Signal Set<br>
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<br>
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</li>
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<li><a href="sigdset.htm">sigdelset()</a>--Delete Signal from Signal Set<br>
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<br>
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</li>
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<li><a href="sigeset.htm">sigemptyset()</a>--Initialize and Empty Signal
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Set<br>
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<br>
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</li>
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<li><a href="sigfset.htm">sigfillset()</a>--Initialize and Fill Signal Set<br>
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<br>
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</li>
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<li><a href="sigismbr.htm">sigismember()</a>--Test for Signal in Signal Set<br>
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<br>
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</li>
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<li><a href="sigpend.htm">sigpending()</a>--Examine Pending Signals<br>
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<br>
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</li>
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<li><a href="sigpmsk.htm">sigprocmask()</a>--Examine and Change Blocked
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Signals<br>
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<br>
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</li>
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<li><a href="sigtwait.htm">sigtimedwait()</a>--Synchronously Accept a Signal
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for Interval of Time<br>
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<br>
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</li>
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<li><a href="sigwait.htm">sigwait()</a>--Synchronously Accept a Signal<br>
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<br>
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</li>
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<li><a href="sigwaiti.htm">sigwaitinfo()</a>--Synchronously Accept a Signal and
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Signal Data<br>
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<br>
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</li>
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<li><a href="sigsleep.htm">sleep()</a>--Suspend Processing for Interval of
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Time</li>
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</ul>
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<br>
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<h3>Example</h3>
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<p>See <a href="../apiref/aboutapis.htm#codedisclaimer">Code disclaimer information</a>
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for information pertaining to code examples.</p>
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<p>The following example replaces the signal mask and then suspends
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processing:</p>
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<pre>
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#include <signal.h>
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#include <unistd.h>
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#include <stdio.h>
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#include <time.h>
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void catcher( int sig ) {
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printf( "inside catcher() function\n" );
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}
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void timestamp( char *str ) {
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time_t t;
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time( &t );
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printf( "%s the time is %s\n", str, ctime(&t) );
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}
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int main( int argc, char *argv[] ) {
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struct sigaction sigact;
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sigset_t block_set;
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sigfillset( &block_set );
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sigdelset( &block_set, SIGALRM );
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sigemptyset( &sigact.sa_mask );
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sigact.sa_flags = 0;
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sigact.sa_handler = catcher;
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sigaction( SIGALRM, &sigact, NULL );
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timestamp( "before sigsuspend()" );
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alarm( 10 );
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sigsuspend( &block_set );
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timestamp( "after sigsuspend()" );
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return( 0 );
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}
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</pre>
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<h3>Output:</h3>
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<pre>
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before sigsuspend() the time is Sun Jan 22 17:11:41 1995
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inside catcher() function
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after sigsuspend() the time is Sun Jan 22 17:11:51 1995
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</pre>
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<br>
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<hr>
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API introduced: V3R6
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<hr>
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<center>
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<table cellpadding="2" cellspacing="2">
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<tr align="center">
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<td valign="middle" align="center"><a href="#Top_Of_Page">Top</a> | <a href=
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"unix.htm">UNIX-Type APIs</a> | <a href="aplist.htm">APIs by category</a></td>
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</tr>
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</table>
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</center>
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</body>
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</html>
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