254 lines
7.3 KiB
HTML
254 lines
7.3 KiB
HTML
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<!-- Copyright (c) 2001 The Open Group, All Rights Reserved -->
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<title>sleep</title>
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</head>
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<body bgcolor="white">
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<script type="text/javascript" language="JavaScript" src="../jscript/codes.js">
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<basefont size="3"> <a name="sleep"></a> <a name="tag_04_130"></a><!-- sleep -->
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<!--header start-->
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<center><font size="2">The Open Group Base Specifications Issue 6<br>
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IEEE Std 1003.1-2001<br>
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Copyright © 2001 The IEEE and The Open Group, All Rights reserved.</font></center>
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<!--header end-->
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<hr size="2" noshade>
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<h4><a name="tag_04_130_01"></a>NAME</h4>
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<blockquote>sleep - suspend execution for an interval</blockquote>
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<h4><a name="tag_04_130_02"></a>SYNOPSIS</h4>
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<blockquote class="synopsis">
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<p><code><tt>sleep</tt> <i>time</i></code></p>
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</blockquote>
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<h4><a name="tag_04_130_03"></a>DESCRIPTION</h4>
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<blockquote>
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<p>The <i>sleep</i> utility shall suspend execution for at least the integral number of seconds specified by the <i>time</i>
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operand.</p>
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</blockquote>
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<h4><a name="tag_04_130_04"></a>OPTIONS</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_04_130_05"></a>OPERANDS</h4>
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<blockquote>
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<p>The following operand shall be supported:</p>
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<dl compact>
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<dt><i>time</i></dt>
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<dd>A non-negative decimal integer specifying the number of seconds for which to suspend execution.</dd>
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</dl>
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</blockquote>
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<h4><a name="tag_04_130_06"></a>STDIN</h4>
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<blockquote>
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<p>Not used.</p>
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</blockquote>
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<h4><a name="tag_04_130_07"></a>INPUT FILES</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_04_130_08"></a>ENVIRONMENT VARIABLES</h4>
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<blockquote>
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<p>The following environment variables shall affect the execution of <i>sleep</i>:</p>
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<dl compact>
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<dt><i>LANG</i></dt>
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<dd>Provide a default value for the internationalization variables that are unset or null. (See the Base Definitions volume of
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IEEE Std 1003.1-2001, <a href="../basedefs/xbd_chap08.html#tag_08_02">Section 8.2, Internationalization Variables</a> for
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the precedence of internationalization variables used to determine the values of locale categories.)</dd>
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<dt><i>LC_ALL</i></dt>
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<dd>If set to a non-empty string value, override the values of all the other internationalization variables.</dd>
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<dt><i>LC_CTYPE</i></dt>
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<dd>Determine the locale for the interpretation of sequences of bytes of text data as characters (for example, single-byte as
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opposed to multi-byte characters in arguments).</dd>
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<dt><i>LC_MESSAGES</i></dt>
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<dd>Determine the locale that should be used to affect the format and contents of diagnostic messages written to standard
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error.</dd>
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<dt><i>NLSPATH</i></dt>
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<dd><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
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Determine the location of message catalogs for the processing of <i>LC_MESSAGES .</i> <img src="../images/opt-end.gif" alt=
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"[Option End]" border="0"></dd>
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</dl>
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</blockquote>
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<h4><a name="tag_04_130_09"></a>ASYNCHRONOUS EVENTS</h4>
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<blockquote>
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<p>If the <i>sleep</i> utility receives a SIGALRM signal, one of the following actions shall be taken:</p>
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<ol>
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<li>
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<p>Terminate normally with a zero exit status.</p>
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</li>
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<li>
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<p>Effectively ignore the signal.</p>
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</li>
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<li>
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<p>Provide the default behavior for signals described in the ASYNCHRONOUS EVENTS section of <a href=
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"xcu_chap01.html#tag_01_11"><i>Utility Description Defaults</i></a> . This could include terminating with a non-zero exit
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status.</p>
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</li>
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</ol>
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<p>The <i>sleep</i> utility shall take the standard action for all other signals.</p>
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</blockquote>
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<h4><a name="tag_04_130_10"></a>STDOUT</h4>
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<blockquote>
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<p>Not used.</p>
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</blockquote>
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<h4><a name="tag_04_130_11"></a>STDERR</h4>
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<blockquote>
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<p>The standard error shall be used only for diagnostic messages.</p>
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</blockquote>
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<h4><a name="tag_04_130_12"></a>OUTPUT FILES</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_04_130_13"></a>EXTENDED DESCRIPTION</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_04_130_14"></a>EXIT STATUS</h4>
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<blockquote>
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<p>The following exit values shall be returned:</p>
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<dl compact>
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<dt> 0</dt>
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<dd>The execution was successfully suspended for at least <i>time</i> seconds, or a SIGALRM signal was received. See the
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ASYNCHRONOUS EVENTS section.</dd>
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<dt>>0</dt>
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<dd>An error occurred.</dd>
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</dl>
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</blockquote>
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<h4><a name="tag_04_130_15"></a>CONSEQUENCES OF ERRORS</h4>
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<blockquote>
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<p>Default.</p>
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</blockquote>
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<hr>
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<div class="box"><em>The following sections are informative.</em></div>
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<h4><a name="tag_04_130_16"></a>APPLICATION USAGE</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_04_130_17"></a>EXAMPLES</h4>
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<blockquote>
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<p>The <i>sleep</i> utility can be used to execute a command after a certain amount of time, as in:</p>
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<pre>
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<tt>(sleep 105;</tt> <i>command</i><tt>) &
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</tt>
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</pre>
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<p>or to execute a command every so often, as in:</p>
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<pre>
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<tt>while true
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do
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</tt> <i>command</i> <tt> sleep 37
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done
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</tt>
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</pre>
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</blockquote>
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<h4><a name="tag_04_130_18"></a>RATIONALE</h4>
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<blockquote>
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<p>The exit status is allowed to be zero when <i>sleep</i> is interrupted by the SIGALRM signal because most implementations of
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this utility rely on the arrival of that signal to notify them that the requested finishing time has been successfully attained.
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Such implementations thus do not distinguish this situation from the successful completion case. Other implementations are allowed
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to catch the signal and go back to sleep until the requested time expires or to provide the normal signal termination
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procedures.</p>
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<p>As with all other utilities that take integral operands and do not specify subranges of allowed values, <i>sleep</i> is required
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by this volume of IEEE Std 1003.1-2001 to deal with <i>time</i> requests of up to 2147483647 seconds. This may mean that
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some implementations have to make multiple calls to the delay mechanism of the underlying operating system if its argument range is
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less than this.</p>
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</blockquote>
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<h4><a name="tag_04_130_19"></a>FUTURE DIRECTIONS</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_04_130_20"></a>SEE ALSO</h4>
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<blockquote>
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<p><a href="wait.html"><i>wait</i></a> , the System Interfaces volume of IEEE Std 1003.1-2001, <a href=
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"../functions/alarm.html"><i>alarm</i>()</a>, <a href="../functions/sleep.html"><i>sleep</i>()</a></p>
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</blockquote>
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<h4><a name="tag_04_130_21"></a>CHANGE HISTORY</h4>
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<blockquote>
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<p>First released in Issue 2.</p>
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</blockquote>
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<div class="box"><em>End of informative text.</em></div>
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<hr>
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<hr size="2" noshade>
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<center><font size="2"><!--footer start-->
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UNIX ® is a registered Trademark of The Open Group.<br>
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POSIX ® is a registered Trademark of The IEEE.<br>
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[ <a href="../mindex.html">Main Index</a> | <a href="../basedefs/contents.html">XBD</a> | <a href=
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"../utilities/contents.html">XCU</a> | <a href="../functions/contents.html">XSH</a> | <a href="../xrat/contents.html">XRAT</a>
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