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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>comm</title></head><body bgcolor="white"><script type="text/javascript" language="JavaScript" src="../jscript/codes.js"></script><basefont size="3"> <a name="comm"></a> <a name="tag_04_23"></a><!-- comm --> <!--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_23_01"></a>NAME</h4><blockquote>comm - select or reject lines common to two files</blockquote><h4><a name="tag_04_23_02"></a>SYNOPSIS</h4><blockquote class="synopsis"><p><code><tt>comm</tt> <b>[</b><tt>-123</tt><b>]</b> <i>file1 file2</i></code></p></blockquote><h4><a name="tag_04_23_03"></a>DESCRIPTION</h4><blockquote><p>The <i>comm</i> utility shall read <i>file1</i> and <i>file2</i>, which should be ordered in the current collating sequence, andproduce three text columns as output: lines only in <i>file1</i>, lines only in <i>file2</i>, and lines in both files.</p><p>If the lines in both files are not ordered according to the collating sequence of the current locale, the results areunspecified.</p></blockquote><h4><a name="tag_04_23_04"></a>OPTIONS</h4><blockquote><p>The <i>comm</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 options shall be supported:</p><dl compact><dt><b>-1</b></dt><dd>Suppress the output column of lines unique to <i>file1</i>.</dd><dt><b>-2</b></dt><dd>Suppress the output column of lines unique to <i>file2</i>.</dd><dt><b>-3</b></dt><dd>Suppress the output column of lines duplicated in <i>file1</i> and <i>file2</i>.</dd></dl></blockquote><h4><a name="tag_04_23_05"></a>OPERANDS</h4><blockquote><p>The following operands shall be supported:</p><dl compact><dt><i>file1</i></dt><dd>A pathname of the first file to be compared. If <i>file1</i> is <tt>'-'</tt> , the standard input shall be used.</dd><dt><i>file2</i></dt><dd>A pathname of the second file to be compared. If <i>file2</i> is <tt>'-'</tt> , the standard input shall be used.</dd></dl><p>If both <i>file1</i> and <i>file2</i> refer to standard input or to the same FIFO special, block special, or character specialfile, the results are undefined.</p></blockquote><h4><a name="tag_04_23_06"></a>STDIN</h4><blockquote><p>The standard input shall be used only if one of the <i>file1</i> or <i>file2</i> operands refers to standard input. See theINPUT FILES section.</p></blockquote><h4><a name="tag_04_23_07"></a>INPUT FILES</h4><blockquote><p>The input files shall be text files.</p></blockquote><h4><a name="tag_04_23_08"></a>ENVIRONMENT VARIABLES</h4><blockquote><p>The following environment variables shall affect the execution of <i>comm</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_COLLATE</i></dt><dd><br>Determine the locale for the collating sequence <i>comm</i> expects to have been used when the input files were sorted.</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 and input files).</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_23_09"></a>ASYNCHRONOUS EVENTS</h4><blockquote><p>Default.</p></blockquote><h4><a name="tag_04_23_10"></a>STDOUT</h4><blockquote><p>The <i>comm</i> utility shall 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> shall write nothing to standard output.</p><p>If the <b>-1</b> option is not selected, lines contained only in <i>file1</i> shall be written using the format:</p><pre><tt>"%s\n", <</tt><i>line in file1</i><tt>></tt></pre><p>If the <b>-2</b> option is not selected, lines contained only in <i>file2</i> are written using the format:</p><pre><tt>"%s%s\n", <</tt><i>lead</i><tt>>, <</tt><i>line in file2</i><tt>></tt></pre><p>where the string <<i>lead</i>> is as follows:</p><dl compact><dt><tab></dt><dd>The <b>-1</b> option is not selected.</dd><dt>null string</dt><dd>The <b>-1</b> option is selected.</dd></dl><p>If the <b>-3</b> option is not selected, lines contained in both files shall be written using the format:</p><pre><tt>"%s%s\n", <</tt><i>lead</i><tt>>, <</tt><i>line in both</i><tt>></tt></pre><p>where the string <<i>lead</i>> is as follows:</p><dl compact><dt><tab><tab></dt><dd>Neither the <b>-1</b> nor the <b>-2</b> option is selected.</dd><dt><tab></dt><dd>Exactly one of the <b>-1</b> and <b>-2</b> options is selected.</dd><dt>null string</dt><dd>Both the <b>-1</b> and <b>-2</b> options are selected.</dd></dl><p>If the input files were ordered according to the collating sequence of the current locale, the lines written shall be in thecollating sequence of the original lines.</p></blockquote><h4><a name="tag_04_23_11"></a>STDERR</h4><blockquote><p>The standard error shall be used only for diagnostic messages.</p></blockquote><h4><a name="tag_04_23_12"></a>OUTPUT FILES</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_23_13"></a>EXTENDED DESCRIPTION</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_23_14"></a>EXIT STATUS</h4><blockquote><p>The following exit values shall be returned:</p><dl compact><dt> 0</dt><dd>All input files were successfully output as specified.</dd><dt>>0</dt><dd>An error occurred.</dd></dl></blockquote><h4><a name="tag_04_23_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_23_16"></a>APPLICATION USAGE</h4><blockquote><p>If the input files are not properly presorted, the output of <i>comm</i> might not be useful.</p></blockquote><h4><a name="tag_04_23_17"></a>EXAMPLES</h4><blockquote><p>If a file named <b>xcu</b> contains a sorted list of the utilities in this volume of IEEE Std 1003.1-2001, a filenamed <b>xpg3</b> contains a sorted list of the utilities specified in the X/Open Portability Guide, Issue 3, and a file named<b>svid89</b> contains a sorted list of the utilities in the System V Interface Definition Third Edition:</p><pre><tt>comm -23 xcu xpg3 | comm -23 - svid89</tt></pre><p>would print a list of utilities in this volume of IEEE Std 1003.1-2001 not specified by either of the otherdocuments:</p><pre><tt>comm -12 xcu xpg3 | comm -12 - svid89</tt></pre><p>would print a list of utilities specified by all three documents, and:</p><pre><tt>comm -12 xpg3 svid89 | comm -23 - xcu</tt></pre><p>would print a list of utilities specified by both XPG3 and the SVID, but not specified in this volume ofIEEE Std 1003.1-2001.</p></blockquote><h4><a name="tag_04_23_18"></a>RATIONALE</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_23_19"></a>FUTURE DIRECTIONS</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_23_20"></a>SEE ALSO</h4><blockquote><p><a href="cmp.html"><i>cmp</i></a> , <a href="diff.html"><i>diff</i></a> , <a href="sort.html"><i>sort</i></a> , <a href="uniq.html"><i>uniq</i></a></p></blockquote><h4><a name="tag_04_23_21"></a>CHANGE HISTORY</h4><blockquote><p>First released in Issue 2.</p></blockquote><h4><a name="tag_04_23_22"></a>Issue 6</h4><blockquote><p>The normative text is reworded to avoid use of the term "must" for application requirements.</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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