258 lines
7.7 KiB
HTML
258 lines
7.7 KiB
HTML
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<!-- Copyright (c) 2001 The Open Group, All Rights Reserved -->
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<title>hash</title>
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</head>
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<body bgcolor="white">
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<script type="text/javascript" language="JavaScript" src="../jscript/codes.js">
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<basefont size="3"> <a name="hash"></a> <a name="tag_04_64"></a><!-- hash -->
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<!--header start-->
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<center><font size="2">The Open Group Base Specifications Issue 6<br>
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IEEE Std 1003.1-2001<br>
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Copyright © 2001 The IEEE and The Open Group, All Rights reserved.</font></center>
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<!--header end-->
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<hr size="2" noshade>
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<h4><a name="tag_04_64_01"></a>NAME</h4>
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<blockquote>hash - remember or report utility locations</blockquote>
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<h4><a name="tag_04_64_02"></a>SYNOPSIS</h4>
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<blockquote class="synopsis">
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<div class="box"><code><tt><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt=
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"[Option Start]" border="0"> hash</tt> <b>[</b><i>utility</i><tt>...</tt><b>]</b><tt><br>
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<br>
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hash -r <img src="../images/opt-end.gif" alt="[Option End]" border="0"></tt></code></div>
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<tt><br>
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</tt></blockquote>
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<h4><a name="tag_04_64_03"></a>DESCRIPTION</h4>
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<blockquote>
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<p>The <i>hash</i> utility shall affect the way the current shell environment remembers the locations of utilities found as
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described in <a href="xcu_chap02.html#tag_02_09_01_01"><i>Command Search and Execution</i></a> . Depending on the arguments
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specified, it shall add utility locations to its list of remembered locations or it shall purge the contents of the list. When no
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arguments are specified, it shall report on the contents of the list.</p>
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<p>Utilities provided as built-ins to the shell shall not be reported by <i>hash</i>.</p>
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</blockquote>
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<h4><a name="tag_04_64_04"></a>OPTIONS</h4>
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<blockquote>
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<p>The <i>hash</i> utility shall conform to the Base Definitions volume of IEEE Std 1003.1-2001, <a href=
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"../basedefs/xbd_chap12.html#tag_12_02">Section 12.2, Utility Syntax Guidelines</a>.</p>
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<p>The following option shall be supported:</p>
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<dl compact>
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<dt><b>-r</b></dt>
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<dd>Forget all previously remembered utility locations.</dd>
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</dl>
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</blockquote>
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<h4><a name="tag_04_64_05"></a>OPERANDS</h4>
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<blockquote>
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<p>The following operand shall be supported:</p>
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<dl compact>
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<dt><i>utility</i></dt>
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<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 more
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slashes, the results are unspecified.</dd>
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</dl>
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</blockquote>
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<h4><a name="tag_04_64_06"></a>STDIN</h4>
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<blockquote>
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<p>Not used.</p>
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</blockquote>
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<h4><a name="tag_04_64_07"></a>INPUT FILES</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_04_64_08"></a>ENVIRONMENT VARIABLES</h4>
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<blockquote>
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<p>The following environment variables shall affect the execution of <i>hash</i>:</p>
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<dl compact>
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<dt><i>LANG</i></dt>
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<dd>Provide a default value for the internationalization variables that are unset or null. (See the Base Definitions volume of
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IEEE Std 1003.1-2001, <a href="../basedefs/xbd_chap08.html#tag_08_02">Section 8.2, Internationalization Variables</a> for
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the precedence of internationalization variables used to determine the values of locale categories.)</dd>
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<dt><i>LC_ALL</i></dt>
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<dd>If set to a non-empty string value, override the values of all the other internationalization variables.</dd>
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<dt><i>LC_CTYPE</i></dt>
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<dd>Determine the locale for the interpretation of sequences of bytes of text data as characters (for example, single-byte as
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opposed to multi-byte characters in arguments).</dd>
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<dt><i>LC_MESSAGES</i></dt>
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<dd>Determine the locale that should be used to affect the format and contents of diagnostic messages written to standard
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error.</dd>
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<dt><i>NLSPATH</i></dt>
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<dd>Determine the location of message catalogs for the processing of <i>LC_MESSAGES .</i></dd>
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<dt><i>PATH</i></dt>
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<dd>Determine the location of <i>utility</i>, as described in the Base Definitions volume of IEEE Std 1003.1-2001, <a
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href="../basedefs/xbd_chap08.html">Chapter 8, Environment Variables</a>.</dd>
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</dl>
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</blockquote>
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<h4><a name="tag_04_64_09"></a>ASYNCHRONOUS EVENTS</h4>
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<blockquote>
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<p>Default.</p>
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</blockquote>
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<h4><a name="tag_04_64_10"></a>STDOUT</h4>
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<blockquote>
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<p>The standard output of <i>hash</i> shall be used when no arguments are specified. Its format is unspecified, but includes the
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pathname of each utility in the list of remembered locations for the current shell environment. This list shall consist of those
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utilities named in previous <i>hash</i> invocations that have been invoked, and may contain those invoked and found through the
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normal command search process.</p>
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</blockquote>
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<h4><a name="tag_04_64_11"></a>STDERR</h4>
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<blockquote>
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<p>The standard error shall be used only for diagnostic messages.</p>
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</blockquote>
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<h4><a name="tag_04_64_12"></a>OUTPUT FILES</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_04_64_13"></a>EXTENDED DESCRIPTION</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_04_64_14"></a>EXIT STATUS</h4>
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<blockquote>
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<p>The following exit values shall be returned:</p>
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<dl compact>
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<dt> 0</dt>
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<dd>Successful completion.</dd>
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<dt>>0</dt>
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<dd>An error occurred.</dd>
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</dl>
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</blockquote>
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<h4><a name="tag_04_64_15"></a>CONSEQUENCES OF ERRORS</h4>
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<blockquote>
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<p>Default.</p>
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</blockquote>
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<hr>
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<div class="box"><em>The following sections are informative.</em></div>
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<h4><a name="tag_04_64_16"></a>APPLICATION USAGE</h4>
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<blockquote>
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<p>Since <i>hash</i> affects the current shell execution environment, it is always provided as a shell regular built-in. If it is
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called in a separate utility execution environment, such as one of the following:</p>
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<pre>
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<tt>nohup hash -r
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find . -type f | xargs hash
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</tt>
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</pre>
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<p>it does not affect the command search process of the caller's environment.</p>
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<p>The <i>hash</i> utility may be implemented as an alias-for example, <a href="../utilities/alias.html"><i>alias</i></a>
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<b>-t -</b>, in which case utilities found through normal command search are not listed by the <i>hash</i> command.</p>
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<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,
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this can be:</p>
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<pre>
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<tt>PATH="$PATH"
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</tt>
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</pre>
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<p>The use of <i>hash</i> with <i>utility</i> names is unnecessary for most applications, but may provide a performance improvement
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on a few implementations; normally, the hashing process is included by default.</p>
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</blockquote>
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<h4><a name="tag_04_64_17"></a>EXAMPLES</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_04_64_18"></a>RATIONALE</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_04_64_19"></a>FUTURE DIRECTIONS</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_04_64_20"></a>SEE ALSO</h4>
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<blockquote>
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<p><a href="xcu_chap02.html#tag_02_09_01_01"><i>Command Search and Execution</i></a></p>
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</blockquote>
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<h4><a name="tag_04_64_21"></a>CHANGE HISTORY</h4>
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<blockquote>
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<p>First released in Issue 2.</p>
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</blockquote>
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<div class="box"><em>End of informative text.</em></div>
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<hr>
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<hr size="2" noshade>
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<center><font size="2"><!--footer start-->
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UNIX ® is a registered Trademark of The Open Group.<br>
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POSIX ® is a registered Trademark of The IEEE.<br>
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[ <a href="../mindex.html">Main Index</a> | <a href="../basedefs/contents.html">XBD</a> | <a href=
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"../utilities/contents.html">XCU</a> | <a href="../functions/contents.html">XSH</a> | <a href="../xrat/contents.html">XRAT</a>
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]</font></center>
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