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Changes to manual/html_node/Back_002dreferences-and-Subexpressions.html

From: Karl Berry
Subject: Changes to manual/html_node/Back_002dreferences-and-Subexpressions.html
Date: Sun, 24 May 2009 18:43:05 +0000

CVSROOT:        /web/grep
Module name:    grep
Changes by:     Karl Berry <karl>       09/05/24 18:43:01

Index: manual/html_node/Back_002dreferences-and-Subexpressions.html
RCS file: manual/html_node/Back_002dreferences-and-Subexpressions.html
diff -N manual/html_node/Back_002dreferences-and-Subexpressions.html
--- /dev/null   1 Jan 1970 00:00:00 -0000
+++ manual/html_node/Back_002dreferences-and-Subexpressions.html        24 May 
2009 18:42:58 -0000      1.1
@@ -0,0 +1,65 @@
+<html lang="en">
+<title>Back-references and Subexpressions - GNU Grep 2.5.4</title>
+<meta http-equiv="Content-Type" content="text/html">
+<meta name="description" content="GNU Grep 2.5.4">
+<meta name="generator" content="makeinfo 4.13">
+<link title="Top" rel="start" href="index.html#Top">
+<link rel="up" href="Regular-Expressions.html#Regular-Expressions" 
title="Regular Expressions">
+<link rel="prev" href="Anchoring.html#Anchoring" title="Anchoring">
+<link rel="next" href="Basic-vs-Extended.html#Basic-vs-Extended" title="Basic 
vs Extended">
+<link href=""; rel="generator-home" 
title="Texinfo Homepage">
+This manual is for `grep', a pattern matching engine.
+Copyright (C) 1999, 2000, 2001, 2002, 2005, 2008, 2009 Free
+Software Foundation, Inc.
+     Permission is granted to copy, distribute and/or modify this
+     document under the terms of the GNU Free Documentation License,
+     Version 1.3 or any later version published by the Free Software
+     Foundation; with no Invariant Sections, with no Front-Cover Texts,
+     and with no Back-Cover Texts.  A copy of the license is included
+     in the section entitled ``GNU Free Documentation License''.
+   -->
+<meta http-equiv="Content-Style-Type" content="text/css">
+<style type="text/css"><!--
+  pre.display { font-family:inherit }
+  pre.format  { font-family:inherit }
+  pre.smalldisplay { font-family:inherit; font-size:smaller }
+  pre.smallformat  { font-family:inherit; font-size:smaller }
+  pre.smallexample { font-size:smaller }
+  pre.smalllisp    { font-size:smaller }
+    { font-variant:small-caps }
+  span.roman { font-family:serif; font-weight:normal; } 
+  span.sansserif { font-family:sans-serif; font-weight:normal; } 
+<div class="node">
+<a name="Back-references-and-Subexpressions"></a>
+<a name="Back_002dreferences-and-Subexpressions"></a>
+Next:&nbsp;<a rel="next" accesskey="n" 
href="Basic-vs-Extended.html#Basic-vs-Extended">Basic vs Extended</a>,
+Previous:&nbsp;<a rel="previous" accesskey="p" 
+Up:&nbsp;<a rel="up" accesskey="u" 
href="Regular-Expressions.html#Regular-Expressions">Regular Expressions</a>
+<h3 class="section">3.5 Back-references and Subexpressions</h3>
+<p><a name="index-subexpression-237"></a><a 
+The back-reference &lsquo;<samp><span 
class="samp">\</span><var>n</var></samp>&rsquo;, where <var>n</var> is a single 
digit, matches
+the substring previously matched by the <var>n</var>th parenthesized 
+of the regular expression. 
+For example, &lsquo;<samp><span class="samp">(a)\1</span></samp>&rsquo; 
matches &lsquo;<samp><span class="samp">aa</span></samp>&rsquo;. 
+When used with alternation, if the group does not participate in the match then
+the back-reference makes the whole match fail. 
+For example, &lsquo;<samp><span class="samp">a(.)|b\1</span></samp>&rsquo;
+will not match &lsquo;<samp><span class="samp">ba</span></samp>&rsquo;. 
+When multiple regular expressions are given with
+&lsquo;<samp><span class="samp">-e</span></samp>&rsquo; or from a file 
(&lsquo;<samp><span class="samp">-f file</span></samp>&rsquo;),
+back-references are local to each expression.
+   </body></html>

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