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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>true</title></head><body bgcolor="white"><basefont size="3"> <a name="true"></a> <a name="tag_04_147"></a><!-- true --> <!--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_04_147_01"></a>NAME</h4><blockquote>true - return true value</blockquote><h4><a name="tag_04_147_02"></a>SYNOPSIS</h4><blockquote class="synopsis"><p><code><tt>true</tt></code></p></blockquote><h4><a name="tag_04_147_03"></a>DESCRIPTION</h4><blockquote><p>The <i>true</i> utility shall return with exit code zero.</p></blockquote><h4><a name="tag_04_147_04"></a>OPTIONS</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_147_05"></a>OPERANDS</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_147_06"></a>STDIN</h4><blockquote><p>Not used.</p></blockquote><h4><a name="tag_04_147_07"></a>INPUT FILES</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_147_08"></a>ENVIRONMENT VARIABLES</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_147_09"></a>ASYNCHRONOUS EVENTS</h4><blockquote><p>Default.</p></blockquote><h4><a name="tag_04_147_10"></a>STDOUT</h4><blockquote><p>Not used.</p></blockquote><h4><a name="tag_04_147_11"></a>STDERR</h4><blockquote><p>Not used.</p></blockquote><h4><a name="tag_04_147_12"></a>OUTPUT FILES</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_147_13"></a>EXTENDED DESCRIPTION</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_147_14"></a>EXIT STATUS</h4><blockquote><p>Zero.</p></blockquote><h4><a name="tag_04_147_15"></a>CONSEQUENCES OF ERRORS</h4><blockquote><p>None.</p></blockquote><hr><div class="box"><em>The following sections are informative.</em></div><h4><a name="tag_04_147_16"></a>APPLICATION USAGE</h4><blockquote><p>This utility is typically used in shell scripts, as shown in the EXAMPLES section. The special built-in utility <b>:</b> issometimes more efficient than <i>true</i>.</p></blockquote><h4><a name="tag_04_147_17"></a>EXAMPLES</h4><blockquote><p>This command is executed forever:</p><pre><tt>while truedo commanddone</tt></pre></blockquote><h4><a name="tag_04_147_18"></a>RATIONALE</h4><blockquote><p>The <i>true</i> utility has been retained in this volume of IEEE Std 1003.1-2001, even though the shell specialbuilt-in <b>:</b> provides similar functionality, because <i>true</i> is widely used in historical scripts and is less cryptic tonovice script readers.</p></blockquote><h4><a name="tag_04_147_19"></a>FUTURE DIRECTIONS</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_147_20"></a>SEE ALSO</h4><blockquote><p><a href="false.html"><i>false</i></a>, <a href="xcu_chap02.html#tag_02_09"><i>Shell Commands</i></a></p></blockquote><h4><a name="tag_04_147_21"></a>CHANGE HISTORY</h4><blockquote><p>First released in Issue 2.</p></blockquote><h4><a name="tag_04_147_22"></a>Issue 6</h4><blockquote><p>IEEE Std 1003.1-2001/Cor 1-2002, item XCU/TC1/D6/39 is applied, replacing the terms ``None'' and ``Default'' from theSTDERR and EXIT STATUS sections, respectively, with terms as defined in <a href="xcu_chap01.html#tag_01_11"><i>Utility DescriptionDefaults</i></a>.</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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