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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>comm</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_130"> </a>NAME</h4><blockquote>comm - select or reject lines common to two files</blockquote><h4><a name = "tag_001_014_131"> </a>SYNOPSIS</h4><blockquote><pre><code>comm <b>[</b>-123<b>] </b><i>file1 file2</i></code></pre></blockquote><h4><a name = "tag_001_014_132"> </a>DESCRIPTION</h4><blockquote>The<i>comm</i>utilitywill read<i>file1</i>and<i>file2</i>,which should be ordered in the current collating sequence,and produce three text columns as output: lines only in<i>file1</i>;lines only in<i>file2</i>;and lines in both files.<p>If the lines in both files are not ordered according to thecollating sequence of the current locale, the results are unspecified.</blockquote><h4><a name = "tag_001_014_133"> </a>OPTIONS</h4><blockquote>The<i>comm</i>utility supports the <b>XBD</b> specification, <a href="../xbd/utilconv.html#usg"><b>Utility Syntax Guidelines</b> </a> .<p>The following options are supported:<dl compact><dt><b>-1</b><dd>Suppress the output column of lines unique to<i>file1</i>.<dt><b>-2</b><dd>Suppress the output column of lines unique to<i>file2</i>.<dt><b>-3</b><dd>Suppress the output column of lines duplicated in<i>file1</i>and<i>file2</i>.</dl></blockquote><h4><a name = "tag_001_014_134"> </a>OPERANDS</h4><blockquote>The following operands are supported:<dl compact><dt><i>file1</i><dd>A pathname of the first file to be compared.If<i>file1</i>is "-", the standard input is used.<dt><i>file2</i><dd>A pathname of the second file to be compared.If<i>file2</i>is "-", the standard input is used.</dl><p>If both<i>file1</i>and<i>file2</i>refer to standard inputor to the same FIFO special,block special or character special file,the results are undefined.</blockquote><h4><a name = "tag_001_014_135"> </a>STDIN</h4><blockquote>The standard input will be used only if one of the<i>file1</i>or<i>file2</i>operandsrefers to standard input.See the INPUT FILES section.</blockquote><h4><a name = "tag_001_014_136"> </a>INPUT FILES</h4><blockquote>The input files must be text files.</blockquote><h4><a name = "tag_001_014_137"> </a>ENVIRONMENT VARIABLES</h4><blockquote>The following environment variables affect the execution of<i>comm</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_COLLATE</i><dd>Determine the locale for thecollating sequence<i>comm</i>expects to havebeen used when the input files were sorted.<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 and input files).<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></dl></blockquote><h4><a name = "tag_001_014_138"> </a>ASYNCHRONOUS EVENTS</h4><blockquote>Default.</blockquote><h4><a name = "tag_001_014_139"> </a>STDOUT</h4><blockquote>The<i>comm</i>utility will produce output depending on the options selected.If the<b>-1</b>,<b>-2</b>and<b>-3</b>options are all selected,<i>comm</i>will write nothing to standard output.<p>If the<b>-1</b>option is not selected, lines contained only in<i>file1</i>will be written using the format:<p><code><tt>"%s\n"</tt>, <<i>line in file1</i>></code><p>If the<b>-2</b>option is not selected, lines contained only in<i>file2</i>will be written using the format:<p><code><tt>"%s%s\n"</tt>, <<i>lead</i>>,<<i>line in file2</i>></code>where the string<<i>lead</i>>is:<dl compact><dt><tab><dd>if the<b>-1</b>option is not selected, or<dt>null string<dd>if the<b>-1</b>option is selected.</dl><p>If the<b>-3</b>option is not selected, lines contained in both fileswill be written using the format:<p><code><tt>"%s%s\n"</tt>, <<i>lead</i>>,<<i>line in both</i>></code>where the string<<i>lead</i>>is:<dl compact><dt><tab><tab><dd>if neither the<b>-1</b>nor the<b>-2</b>option is selected, or<dt><tab><dd>if exactly one of the<b>-1</b>and<b>-2</b>options is selected, or<dt>null string<dd>if both the<b>-1</b>and<b>-2</b>options are selected.</dl><p>If the input files were ordered according to the collatingsequence of the current locale, the lines written will be inthe collating sequence of the original lines.</blockquote><h4><a name = "tag_001_014_140"> </a>STDERR</h4><blockquote>Used only for diagnostic messages.</blockquote><h4><a name = "tag_001_014_141"> </a>OUTPUT FILES</h4><blockquote>None.</blockquote><h4><a name = "tag_001_014_142"> </a>EXTENDED DESCRIPTION</h4><blockquote>None.</blockquote><h4><a name = "tag_001_014_143"> </a>EXIT STATUS</h4><blockquote>The following exit values are returned:<dl compact><dt>0<dd>All input files were successfully output as specified.<dt>>0<dd>An error occurred.</dl></blockquote><h4><a name = "tag_001_014_144"> </a>CONSEQUENCES OF ERRORS</h4><blockquote>Default.</blockquote><h4><a name = "tag_001_014_145"> </a>APPLICATION USAGE</h4><blockquote>If the input files are not properly presorted, the output of<i>comm</i>might not be useful.</blockquote><h4><a name = "tag_001_014_146"> </a>EXAMPLES</h4><blockquote>If a file named<b>xpg4</b>contains a sorted list of the utilitiesin this specification, a file named<b>xpg3</b>contains a sorted listof the utilities specified in the<b>X/Open Portability Guide</b>, <b>Issue 3</b>, and a file named<b>svid89</b>contains a sorted list of the utilitiesin the System V Interface Definition Third Edition:<pre><code>comm -23 xpg4 xpg3 | comm -23 - svid89</code></pre>would print a list of utilities in this specification not specifiedby either of the other documents;<pre><code>comm -12 xpg4 xpg3 | comm -12 - svid89</code></pre>would print a list of utilities specified by all three documents; and<pre><code>comm -12 xpg3 svid89 | comm -23 - xpg4</code></pre>would print a list of utilities specified by both XPG3 and the SVID,but not specified in this specification.</blockquote><h4><a name = "tag_001_014_147"> </a>FUTURE DIRECTIONS</h4><blockquote>None.</blockquote><h4><a name = "tag_001_014_148"> </a>SEE ALSO</h4><blockquote><i><a href="cmp.html">cmp</a></i>,<i><a href="diff.html">diff</a></i>,<i><a href="sort.html">sort</a></i>,<i><a href="uniq.html">uniq</a></i>.</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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