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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><html><head><!-- Copyright 1997 The Open Group, All Rights Reserved --><title>hash</title></head><body bgcolor=white><center><font size=2>The Single UNIX ® Specification, Version 2<br>Copyright © 1997 The Open Group</font></center><hr size=2 noshade><h4><a name = "tag_001_014_909"> </a>NAME</h4><blockquote>hash - remember or report utility locations</blockquote><h4><a name = "tag_001_014_910"> </a>SYNOPSIS</h4><blockquote><pre><code>hash <b>[</b><i>utility</i>...<b>]</b>hash -r </code></pre></blockquote><h4><a name = "tag_001_014_911"> </a>DESCRIPTION</h4><blockquote>The<i>hash</i>utility affects the way the current shell environmentremembers the locations of utilities found as described in<xref href=cmdsea><a href="chap2.html#tag_001_009_001_001">Command Search and Execution</a></xref>.Depending on the arguments specified, it adds utilitylocations to its list of remembered locationsor it purges the contents of the list.When no arguments are specified,it reports on the contents of the list.<p>Utilities provided as built-ins to the shellare not reported by<i>hash</i>.</blockquote><h4><a name = "tag_001_014_912"> </a>OPTIONS</h4><blockquote>The<i>hash</i>utility supports the <b>XBD</b> specification, <a href="../xbd/utilconv.html#usg"><b>Utility Syntax Guidelines</b> </a> .<p>The following option is supported:<dl compact><dt><b>-r</b><dd>Forget all previously remembered utility locations.</dl></blockquote><h4><a name = "tag_001_014_913"> </a>OPERANDS</h4><blockquote>The following operand is supported:<dl compact><dt><i>utility</i><dd>The name of a utility to be searched for and addedto the list of remembered locations.If<i>utility</i>contains one or more slashes, the results are unspecified.</dl></blockquote><h4><a name = "tag_001_014_914"> </a>STDIN</h4><blockquote>Not used.</blockquote><h4><a name = "tag_001_014_915"> </a>INPUT FILES</h4><blockquote>None.</blockquote><h4><a name = "tag_001_014_916"> </a>ENVIRONMENT VARIABLES</h4><blockquote>The following environment variables affect the execution of<i>hash</i>:<dl compact><dt><i>LANG</i><dd>Provide a default value for the internationalisation variablesthat are unset or null.If<i>LANG</i>is unset or null, the corresponding value from theimplementation-dependent default locale will be used.If any of the internationalisation variables contains an invalid setting, theutility will behave as if none of the variables had been defined.<dt><i>LC_ALL</i><dd>If set to a non-empty string value,override the values of all the other internationalisation variables.<dt><i>LC_CTYPE</i><dd>Determine thelocale for the interpretation of sequences of bytes of text data ascharacters (for example, single- as opposed to multi-byte charactersin arguments).<dt><i>LC_MESSAGES</i><dd>Determine the locale that should be used to affectthe format and contents of diagnosticmessages written to standard error.<dt><i>NLSPATH</i><dd>Determine the location of message cataloguesfor the processing of<i>LC_MESSAGES .</i><dt><i>PATH</i><dd>Determine the location of<i>utility</i>,as described inthe <b>XBD</b> specification, <a href="../xbd/envvar.html"><b>Environment Variables</b> </a> .</dl></blockquote><h4><a name = "tag_001_014_917"> </a>ASYNCHRONOUS EVENTS</h4><blockquote>Default.</blockquote><h4><a name = "tag_001_014_918"> </a>STDOUT</h4><blockquote>The standard output of<i>hash</i>is used when no arguments are specified.Its format is unspecified, but includesthe pathname of each utility in the list of remembered locationsfor the current shell environment.This list consists of those utilities named in previous<i>hash</i>invocations that have been invoked,and may contain those invoked and found through thenormal command search process.</blockquote><h4><a name = "tag_001_014_919"> </a>STDERR</h4><blockquote>Used only for diagnostic messages.</blockquote><h4><a name = "tag_001_014_920"> </a>OUTPUT FILES</h4><blockquote>None.</blockquote><h4><a name = "tag_001_014_921"> </a>EXTENDED DESCRIPTION</h4><blockquote>None.</blockquote><h4><a name = "tag_001_014_922"> </a>EXIT STATUS</h4><blockquote>The following exit values are returned:<dl compact><dt>0<dd>Successful completion.<dt>>0<dd>An error occurred.</dl></blockquote><h4><a name = "tag_001_014_923"> </a>CONSEQUENCES OF ERRORS</h4><blockquote>Default.</blockquote><h4><a name = "tag_001_014_924"> </a>APPLICATION USAGE</h4><blockquote>Since<i>hash</i>affects the current shell execution environment,it is always provided as a shell regular built-in.If it is called in a separate utility execution environment,such as one of the following:<pre><code>nohup hash -rfind . -type f | xargs hash</code></pre>it will not affect the command search process of the caller's environment.<p>The<i>hash</i>utility may be implemented as an alias, for example,<i><a href="alias.html">alias</a></i><b>-t -</b>,in which case utilities found through normal command searchwill not be listed by the<i>hash</i>command.<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:<pre><code>PATH="$PATH"</code></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 hashingprocess is included by default.</blockquote><h4><a name = "tag_001_014_925"> </a>EXAMPLES</h4><blockquote>None.</blockquote><h4><a name = "tag_001_014_926"> </a>FUTURE DIRECTIONS</h4><blockquote>None.</blockquote><h4><a name = "tag_001_014_927"> </a>SEE ALSO</h4><blockquote><xref href=cmdsea><a href="chap2.html#tag_001_009_001_001">Command Search and Execution</a></xref>.<br></blockquote><hr size=2 noshade><center><font size=2>UNIX ® is a registered Trademark of The Open Group.<br>Copyright © 1997 The Open Group<br> [ <a href="../index.html">Main Index</a> | <a href="../xshix.html">XSH</a> | <a href="../xcuix.html">XCU</a> | <a href="../xbdix.html">XBD</a> | <a href="../cursesix.html">XCURSES</a> | <a href="../xnsix.html">XNS</a> ]</font></center><hr size=2 noshade></body></html>⌨️ 快捷键说明
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