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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>hash</title></head><body bgcolor="white"><script type="text/javascript" language="JavaScript" src="../jscript/codes.js"></script><basefont size="3"> <a name="hash"></a> <a name="tag_04_64"></a><!-- hash --> <!--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_64_01"></a>NAME</h4><blockquote>hash - remember or report utility locations</blockquote><h4><a name="tag_04_64_02"></a>SYNOPSIS</h4><blockquote class="synopsis"><div class="box"><code><tt><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> hash</tt> <b>[</b><i>utility</i><tt>...</tt><b>]</b><tt><br><br>hash -r <img src="../images/opt-end.gif" alt="[Option End]" border="0"></tt></code></div><tt><br></tt></blockquote><h4><a name="tag_04_64_03"></a>DESCRIPTION</h4><blockquote><p>The <i>hash</i> utility shall affect the way the current shell environment remembers the locations of utilities found asdescribed in <a href="xcu_chap02.html#tag_02_09_01_01"><i>Command Search and Execution</i></a> . Depending on the argumentsspecified, it shall add utility locations to its list of remembered locations or it shall purge the contents of the list. When noarguments are specified, it shall report on the contents of the list.</p><p>Utilities provided as built-ins to the shell shall not be reported by <i>hash</i>.</p></blockquote><h4><a name="tag_04_64_04"></a>OPTIONS</h4><blockquote><p>The <i>hash</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>-r</b></dt><dd>Forget all previously remembered utility locations.</dd></dl></blockquote><h4><a name="tag_04_64_05"></a>OPERANDS</h4><blockquote><p>The following operand shall be supported:</p><dl compact><dt><i>utility</i></dt><dd>The name of a utility to be searched for and added to the list of remembered locations. If <i>utility</i> contains one or moreslashes, the results are unspecified.</dd></dl></blockquote><h4><a name="tag_04_64_06"></a>STDIN</h4><blockquote><p>Not used.</p></blockquote><h4><a name="tag_04_64_07"></a>INPUT FILES</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_64_08"></a>ENVIRONMENT VARIABLES</h4><blockquote><p>The following environment variables shall affect the execution of <i>hash</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>Determine the location of message catalogs for the processing of <i>LC_MESSAGES .</i></dd><dt><i>PATH</i></dt><dd>Determine the location of <i>utility</i>, as described in the Base Definitions volume of IEEE Std 1003.1-2001, <ahref="../basedefs/xbd_chap08.html">Chapter 8, Environment Variables</a>.</dd></dl></blockquote><h4><a name="tag_04_64_09"></a>ASYNCHRONOUS EVENTS</h4><blockquote><p>Default.</p></blockquote><h4><a name="tag_04_64_10"></a>STDOUT</h4><blockquote><p>The standard output of <i>hash</i> shall be used when no arguments are specified. Its format is unspecified, but includes thepathname of each utility in the list of remembered locations for the current shell environment. This list shall consist of thoseutilities named in previous <i>hash</i> invocations that have been invoked, and may contain those invoked and found through thenormal command search process.</p></blockquote><h4><a name="tag_04_64_11"></a>STDERR</h4><blockquote><p>The standard error shall be used only for diagnostic messages.</p></blockquote><h4><a name="tag_04_64_12"></a>OUTPUT FILES</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_64_13"></a>EXTENDED DESCRIPTION</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_64_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>An error occurred.</dd></dl></blockquote><h4><a name="tag_04_64_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_64_16"></a>APPLICATION USAGE</h4><blockquote><p>Since <i>hash</i> affects the current shell execution environment, it is always provided as a shell regular built-in. If it iscalled in a separate utility execution environment, such as one of the following:</p><pre><tt>nohup hash -rfind . -type f | xargs hash</tt></pre><p>it does not affect the command search process of the caller's environment.</p><p>The <i>hash</i> utility may be implemented as an alias-for example, <a href="../utilities/alias.html"><i>alias</i></a><b>-t -</b>, in which case utilities found through normal command search are not listed by the <i>hash</i> command.</p><p>The effects of <i>hash</i> <b>-r</b> can also be achieved portably by resetting the value of <i>PATH ;</i> in the simplest form,this can be:</p><pre><tt>PATH="$PATH"</tt></pre><p>The use of <i>hash</i> with <i>utility</i> names is unnecessary for most applications, but may provide a performance improvementon a few implementations; normally, the hashing process is included by default.</p></blockquote><h4><a name="tag_04_64_17"></a>EXAMPLES</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_64_18"></a>RATIONALE</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_64_19"></a>FUTURE DIRECTIONS</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_64_20"></a>SEE ALSO</h4><blockquote><p><a href="xcu_chap02.html#tag_02_09_01_01"><i>Command Search and Execution</i></a></p></blockquote><h4><a name="tag_04_64_21"></a>CHANGE HISTORY</h4><blockquote><p>First released in Issue 2.</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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