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8.0 KiB
HTML
308 lines
8.0 KiB
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<head>
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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>Qp0sEnableSignals()--Enable Process for Signals</title>
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<!-- US Government Users Restricted Rights -->
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<!-- Use, duplication or disclosure restricted by -->
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<!-- GSA ADP Schedule Contract with IBM Corp. -->
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<!-- Begin Header Records ========================================== -->
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<!-- UNIX5 SCRIPT J converted by B2H R4.1 (346) (CMS) by V2KEA304 -->
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<!-- at RCHVMW2 on 17 Feb 1999 at 11:05:09 -->
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<!-- Edited by Kersten Feb 02 -->
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<!--End Header Records -->
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<link rel="stylesheet" type="text/css" href="../rzahg/ic.css">
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</head>
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<body>
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<a name="Top_Of_Page"></a>
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<!-- Java sync-link -->
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<script type="text/javascript" language="Javascript" src="../rzahg/synch.js">
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</script>
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<h2>Qp0sEnableSignals()--Enable Process for Signals</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 Qp0sEnableSignals( void );
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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>Qp0sEnableSignals()</strong> function enables the process to
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receive signals.</p>
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<p>The <strong>Qp0sEnableSignals()</strong> function causes the process signal
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vector to be initialized for the set of supported signals. The signal handling
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action for each supported signal is set to the default action, as defined by
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<strong>sigaction()</strong> (see <a href="sigactn.htm">sigaction()--Examine
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and Change Signal Action</a>). The signal blocking mask of the calling thread
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is set to the empty signal set (see <a href="sigeset.htm">
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sigemptyset()--Initialize and Empty Signal Set</a>).</p>
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<p>If the process is currently enabled for signals, a call to the <strong>
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Qp0sEnableSignals()</strong> has no effect. That is, the process signal vector
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and the signal blocking mask of the calling thread are unchanged and an
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[EALREADY] error is returned.</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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<p>None</p>
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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>0</em></td>
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<td align="left" valign="top"><strong>Qp0sEnableSignals()</strong> was
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successful.</td>
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</tr>
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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>Qp0sEnableSignals()</strong> was not
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successful. The <em>errno</em> variable is set to indicate the error.</td>
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</tr>
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</table>
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<br>
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<br>
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<h3>Error Conditions</h3>
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<p>If <strong>Qp0sEnableSignals()</strong> is not successful, <em>errno</em>
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usually indicates one of the following errors. Under some conditions, <em>
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errno</em> could indicate an error other than those listed here.</p>
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<dl>
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<dt><em>[EALREADY]</em></dt>
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<dd>
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<p>Operation already in progress.</p>
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<p>The calling process is currently enabled for signals.</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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<li style="list-style: none"><br>
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</li>
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</ul>
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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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<ol>
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<li>Processes, by default, are not eligible to receive signals from other
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processes or the system. The <strong>Qp0sEnableSignals</strong>() function
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allows the calling process to receive signals from other processes or the
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system without having to call other signal functions that enable the process
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for signals.
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<p>Use of the following functions enable a process for signals:</p>
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<ul>
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<li>alarm()</li>
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<li>getpgrp()</li>
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<li>getpid()</li>
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<li>kill()</li>
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<li>pause()</li>
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<li>Qp0wGetPgrp()</li>
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<li>Qp0wGetPid()</li>
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<li>setitimer()</li>
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<li>sigaction()</li>
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<li>sigprocmask()</li>
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<li>sigsuspend()</li>
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<li>sigtimedwait()</li>
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<li>sigwait()</li>
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<li>sigwaitinfo()</li>
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<li>sleep()</li>
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</ul>
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<p>Any of the Pthread APIs. See <a href="rzah4mst.htm">Pthread APIs</a> for
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more information.</p>
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</li>
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<li>Once a process has been enabled for signals, it remains eligible to receive
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signals until either it ends or some user action is taken to prevent the
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delivery of signals. The user of signals can prevent the signals from being
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delivered by calling the <strong>sigprocmask()</strong> function. The user can
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also ignore the signal by calling the <strong>sigaction()</strong> function.
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However, not all signals can be blocked or ignored. For details, see <a href=
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"sigactn.htm">sigaction()--Examine and Change Signal Action</a> and <a href=
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"sigpmsk.htm">sigprocmask()--Examine and Change Blocked Signals</a>.<br>
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<br>
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</li>
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<li>If a process has not been enabled for signals, the signal blocking mask for
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any thread created in the process will be set to the empty set.<br>
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<br>
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</li>
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<li>If a process with multiple threads is disabled for signals by calling
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<strong>Qp0sDisableSignals()</strong> and then later re-enabled for signals,
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only the thread that causes signals to be enabled will have its signal blocking
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mask changed. The signal blocking mask for all other threads will be the value
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last used to set the signal blocking mask for those threads.</li>
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</ol>
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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="sigkill.htm">kill()</a>--Send Signal to Process or Group of
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Processes<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="setitime.htm">setitimer()</a>--Set Value for Interval Timer<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="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="sigsusp.htm">sigsuspend()</a>--Wait for Signal<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 shows how a process can reset its signal vector and
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signal blocking mask:</p>
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<pre>
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#include <signal.h>
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#include <errno.h>
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int resetSignals( void ) {
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int return_value;
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return_value = Qp0sEnableSignals();
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if( return_value == -1 ) {
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Qp0sDisableSignals();
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return_value = Qp0sEnableSignals();
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}
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return( return_value );
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}
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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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