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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>alias</title></head><body bgcolor="white"><script type="text/javascript" language="JavaScript" src="../jscript/codes.js"></script><basefont size="3"> <a name="alias"></a> <a name="tag_04_02"></a><!-- alias --> <!--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_02_01"></a>NAME</h4><blockquote>alias - define or display aliases</blockquote><h4><a name="tag_04_02_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"> alias</tt> <b>[</b><i>alias-name</i><b>[</b><tt>=</tt><i>string</i><b>]</b><tt>...</tt><b>]</b><tt><img src="../images/opt-end.gif" alt="[Option End]" border="0"></tt></code></div></blockquote><h4><a name="tag_04_02_03"></a>DESCRIPTION</h4><blockquote><p>The <i>alias</i> utility shall create or redefine alias definitions or write the values of existing alias definitions tostandard output. An alias definition provides a string value that shall replace a command name when it is encountered; see <a href="xcu_chap02.html#tag_02_03_01"><i>Alias Substitution</i></a> .</p><p>An alias definition shall affect the current shell execution environment and the execution environments of the subshells of thecurrent shell. When used as specified by this volume of IEEE Std 1003.1-2001, the alias definition shall not affect theparent process of the current shell nor any utility environment invoked by the shell; see <a href="xcu_chap02.html#tag_02_12"><i>Shell Execution Environment</i></a> .</p></blockquote><h4><a name="tag_04_02_04"></a>OPTIONS</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_02_05"></a>OPERANDS</h4><blockquote><p>The following operands shall be supported:</p><dl compact><dt><i>alias-name</i></dt><dd>Write the alias definition to standard output.</dd><dt><i>alias-name</i>=<i>string</i></dt><dd><br>Assign the value of <i>string</i> to the alias <i>alias-name</i>.</dd></dl><p>If no operands are given, all alias definitions shall be written to standard output.</p></blockquote><h4><a name="tag_04_02_06"></a>STDIN</h4><blockquote><p>Not used.</p></blockquote><h4><a name="tag_04_02_07"></a>INPUT FILES</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_02_08"></a>ENVIRONMENT VARIABLES</h4><blockquote><p>The following environment variables shall affect the execution of <i>alias</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_02_09"></a>ASYNCHRONOUS EVENTS</h4><blockquote><p>Default.</p></blockquote><h4><a name="tag_04_02_10"></a>STDOUT</h4><blockquote><p>The format for displaying aliases (when no operands or only <i>name</i> operands are specified) shall be:</p><pre><tt>"%s=%s\n",</tt> <i>name</i><tt>,</tt> <i>value</i></pre><p>The <i>value</i> string shall be written with appropriate quoting so that it is suitable for reinput to the shell. See thedescription of shell quoting in <a href="xcu_chap02.html#tag_02_02"><i>Quoting</i></a> .</p></blockquote><h4><a name="tag_04_02_11"></a>STDERR</h4><blockquote><p>The standard error shall be used only for diagnostic messages.</p></blockquote><h4><a name="tag_04_02_12"></a>OUTPUT FILES</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_02_13"></a>EXTENDED DESCRIPTION</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_02_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>name</i> operands specified did not have an alias definition, or an error occurred.</dd></dl></blockquote><h4><a name="tag_04_02_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_02_16"></a>APPLICATION USAGE</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_02_17"></a>EXAMPLES</h4><blockquote><ol><li><p>Change <a href="../utilities/ls.html"><i>ls</i></a> to give a columnated, more annotated output:</p><pre><tt>alias ls="ls -CF"</tt></pre></li><li><p>Create a simple "redo" command to repeat previous entries in the command history file:</p><pre><tt>alias r='fc -s'</tt></pre></li><li><p>Use 1K units for <a href="../utilities/du.html"><i>du</i></a>:</p><pre><tt>alias du=du\ -k</tt></pre></li><li><p>Set up <a href="../utilities/nohup.html"><i>nohup</i></a> so that it can deal with an argument that is itself an alias name:</p><pre><tt>alias nohup="nohup "</tt></pre></li></ol></blockquote><h4><a name="tag_04_02_18"></a>RATIONALE</h4><blockquote><p>The <i>alias</i> description is based on historical KornShell implementations. Known differences exist between that and the Cshell. 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>Since <i>alias</i> affects the current shell execution environment, it is generally provided as a shell regular built-in.</p><p>Historical versions of the KornShell have allowed aliases to be exported to scripts that are invoked by the same shell. This istriggered by the <i>alias</i> <b>-x</b> flag; it is allowed by this volume of IEEE Std 1003.1-2001 only when an explicitextension such as <b>-x</b> is used. The standard developers considered that aliases were of use primarily to interactive users andthat they should normally not affect shell scripts called by those users; functions are available to such scripts.</p><p>Historical versions of the KornShell had not written aliases in a quoted manner suitable for reentry to the shell, but thisvolume of IEEE Std 1003.1-2001 has made this a requirement for all similar output. Therefore, consistency with thisvolume of IEEE Std 1003.1-2001 was chosen over this detail of historical practice.</p></blockquote><h4><a name="tag_04_02_19"></a>FUTURE DIRECTIONS</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_02_20"></a>SEE ALSO</h4><blockquote><p><a href="xcu_chap02.html#tag_02_09_05"><i>Function Definition Command</i></a></p></blockquote><h4><a name="tag_04_02_21"></a>CHANGE HISTORY</h4><blockquote><p>First released in Issue 4.</p></blockquote><h4><a name="tag_04_02_22"></a>Issue 6</h4><blockquote><p>This utility is marked as part of the User Portability Utilities option.</p><p>The APPLICATION USAGE section is added.</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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