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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) 2001-2003 The Open Group, All Rights Reserved --><title>unalias</title></head><body bgcolor="white"><script type="text/javascript" language="JavaScript" src="../jscript/codes.js"></script><basefont size="3"> <a name="unalias"></a> <a name="tag_04_153"></a><!-- unalias --> <!--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_04_153_01"></a>NAME</h4><blockquote>unalias - remove alias definitions</blockquote><h4><a name="tag_04_153_02"></a>SYNOPSIS</h4><blockquote class="synopsis"><div class="box"><code><tt><sup>[<a href="javascript:open_code('UP')">UP</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> unalias</tt> <i>alias-name</i><tt>...<br><br> unalias -a <img src="../images/opt-end.gif" alt="[Option End]" border="0"></tt></code></div><tt><br></tt></blockquote><h4><a name="tag_04_153_03"></a>DESCRIPTION</h4><blockquote><p>The <i>unalias</i> utility shall remove the definition for each alias name specified. See <a href="xcu_chap02.html#tag_02_03_01"><i>Alias Substitution</i></a> . The aliases shall be removed from the current shell executionenvironment; see <a href="xcu_chap02.html#tag_02_12"><i>Shell Execution Environment</i></a> .</p></blockquote><h4><a name="tag_04_153_04"></a>OPTIONS</h4><blockquote><p>The <i>unalias</i> utility shall conform to the Base Definitions volume of IEEE Std 1003.1-2001, <a href="../basedefs/xbd_chap12.html#tag_12_02">Section 12.2, Utility Syntax Guidelines</a>.</p><p>The following option shall be supported:</p><dl compact><dt><b>-a</b></dt><dd>Remove all alias definitions from the current shell execution environment.</dd></dl></blockquote><h4><a name="tag_04_153_05"></a>OPERANDS</h4><blockquote><p>The following operand shall be supported:</p><dl compact><dt><i>alias-name</i></dt><dd>The name of an alias to be removed.</dd></dl></blockquote><h4><a name="tag_04_153_06"></a>STDIN</h4><blockquote><p>Not used.</p></blockquote><h4><a name="tag_04_153_07"></a>INPUT FILES</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_153_08"></a>ENVIRONMENT VARIABLES</h4><blockquote><p>The following environment variables shall affect the execution of <i>unalias</i>:</p><dl compact><dt><i>LANG</i></dt><dd>Provide a default value for the internationalization variables that are unset or null. (See the Base Definitions volume ofIEEE Std 1003.1-2001, <a href="../basedefs/xbd_chap08.html#tag_08_02">Section 8.2, Internationalization Variables</a> forthe precedence of internationalization variables used to determine the values of locale categories.)</dd><dt><i>LC_ALL</i></dt><dd>If set to a non-empty string value, override the values of all the other internationalization variables.</dd><dt><i>LC_CTYPE</i></dt><dd>Determine the locale for the interpretation of sequences of bytes of text data as characters (for example, single-byte asopposed to multi-byte characters in arguments).</dd><dt><i>LC_MESSAGES</i></dt><dd>Determine the locale that should be used to affect the format and contents of diagnostic messages written to standarderror.</dd><dt><i>NLSPATH</i></dt><dd><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">Determine the location of message catalogs for the processing of <i>LC_MESSAGES .</i> <img src="../images/opt-end.gif" alt="[Option End]" border="0"></dd></dl></blockquote><h4><a name="tag_04_153_09"></a>ASYNCHRONOUS EVENTS</h4><blockquote><p>Default.</p></blockquote><h4><a name="tag_04_153_10"></a>STDOUT</h4><blockquote><p>Not used.</p></blockquote><h4><a name="tag_04_153_11"></a>STDERR</h4><blockquote><p>The standard error shall be used only for diagnostic messages.</p></blockquote><h4><a name="tag_04_153_12"></a>OUTPUT FILES</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_153_13"></a>EXTENDED DESCRIPTION</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_153_14"></a>EXIT STATUS</h4><blockquote><p>The following exit values shall be returned:</p><dl compact><dt> 0</dt><dd>Successful completion.</dd><dt>>0</dt><dd>One of the <i>alias-name</i> operands specified did not represent a valid alias definition, or an error occurred.</dd></dl></blockquote><h4><a name="tag_04_153_15"></a>CONSEQUENCES OF ERRORS</h4><blockquote><p>Default.</p></blockquote><hr><div class="box"><em>The following sections are informative.</em></div><h4><a name="tag_04_153_16"></a>APPLICATION USAGE</h4><blockquote><p>Since <i>unalias</i> affects the current shell execution environment, it is generally provided as a shell regular built-in.</p></blockquote><h4><a name="tag_04_153_17"></a>EXAMPLES</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_153_18"></a>RATIONALE</h4><blockquote><p>The <i>unalias</i> description is based on that from historical KornShell implementations. Known differences exist between thatand the C shell. The KornShell version was adopted to be consistent with all the other KornShell features in this volume ofIEEE Std 1003.1-2001, such as command line editing.</p><p>The <b>-a</b> option is the equivalent of the <i>unalias</i> * form of the C shell and is provided to address security concernsabout unknown aliases entering the environment of a user (or application) through the allowable implementation-defined predefinedalias route or as a result of an <i>ENV</i> file. (Although <i>unalias</i> could be used to simplify the "secure" shell scriptshown in the <a href="../utilities/command.html"><i>command</i></a> rationale, it does not obviate the need to quote all commandnames. An initial call to <i>unalias</i> <b>-a</b> would have to be quoted in case there was an alias for <i>unalias</i>.)</p></blockquote><h4><a name="tag_04_153_19"></a>FUTURE DIRECTIONS</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_153_20"></a>SEE ALSO</h4><blockquote><p><a href="xcu_chap02.html#tag_02"><i>Shell Command Language</i></a> , <a href="alias.html"><i>alias</i></a></p></blockquote><h4><a name="tag_04_153_21"></a>CHANGE HISTORY</h4><blockquote><p>First released in Issue 4.</p></blockquote><h4><a name="tag_04_153_22"></a>Issue 6</h4><blockquote><p>This utility is marked as part of the User Portability Utilities option.</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
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