CVSROOT: /webcvs/grep Module name: grep Changes by: Jim Meyering <meyering> 23/03/22 22:55:22
Index: html_node/Back_002dreferences-and-Subexpressions.html =================================================================== RCS file: /webcvs/grep/grep/manual/html_node/Back_002dreferences-and-Subexpressions.html,v retrieving revision 1.33 retrieving revision 1.34 diff -u -b -r1.33 -r1.34 --- html_node/Back_002dreferences-and-Subexpressions.html 3 Sep 2022 19:33:14 -0000 1.33 +++ html_node/Back_002dreferences-and-Subexpressions.html 23 Mar 2023 02:55:20 -0000 1.34 @@ -1,11 +1,11 @@ -<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd";> +<!DOCTYPE html> <html> -<!-- Created by GNU Texinfo 6.8, https://www.gnu.org/software/texinfo/ --> +<!-- Created by GNU Texinfo 7.0dev, https://www.gnu.org/software/texinfo/ --> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <!-- This manual is for grep, a pattern matching engine. -Copyright (C) 1999-2002, 2005, 2008-2022 Free Software Foundation, +Copyright © 1999-2002, 2005, 2008-2023 Free Software Foundation, Inc. Permission is granted to copy, distribute and/or modify this document @@ -14,10 +14,10 @@ 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". --> -<title>Back-references and Subexpressions (GNU Grep 3.8)</title> +<title>Back-references and Subexpressions (GNU Grep 3.10)</title> -<meta name="description" content="Back-references and Subexpressions (GNU Grep 3.8)"> -<meta name="keywords" content="Back-references and Subexpressions (GNU Grep 3.8)"> +<meta name="description" content="Back-references and Subexpressions (GNU Grep 3.10)"> +<meta name="keywords" content="Back-references and Subexpressions (GNU Grep 3.10)"> <meta name="resource-type" content="document"> <meta name="distribution" content="global"> <meta name="Generator" content="makeinfo"> @@ -31,21 +31,8 @@ <link href="Anchoring.html" rel="prev" title="Anchoring"> <style type="text/css"> <!-- -a.copiable-anchor {visibility: hidden; text-decoration: none; line-height: 0em} -a.summary-letter {text-decoration: none} -blockquote.indentedblock {margin-right: 0em} -div.display {margin-left: 3.2em} -div.example {margin-left: 3.2em} -kbd {font-style: oblique} -pre.display {font-family: inherit} -pre.format {font-family: inherit} -pre.menu-comment {font-family: serif} -pre.menu-preformatted {font-family: serif} -span.nolinebreak {white-space: nowrap} -span.roman {font-family: initial; font-weight: normal} -span.sansserif {font-family: sans-serif; font-weight: normal} -span:hover a.copiable-anchor {visibility: visible} -ul.no-bullet {list-style: none} +a.copiable-link {visibility: hidden; text-decoration: none; line-height: 0em} +span:hover a.copiable-link {visibility: visible} --> </style> <link rel="stylesheet" type="text/css" href="https://www.gnu.org/software/gnulib/manual.css";> @@ -54,32 +41,32 @@ </head> <body lang="en"> -<div class="section" id="Back_002dreferences-and-Subexpressions"> -<div class="header"> +<div class="section-level-extent" id="Back_002dreferences-and-Subexpressions"> +<div class="nav-panel"> <p> Next: <a href="Basic-vs-Extended.html" accesskey="n" rel="next">Basic vs Extended Regular Expressions</a>, Previous: <a href="Anchoring.html" accesskey="p" rel="prev">Anchoring</a>, Up: <a href="Regular-Expressions.html" accesskey="u" rel="up">Regular Expressions</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Index.html" title="Index" rel="index">Index</a>]</p> </div> <hr> -<span id="Back_002dreferences-and-Subexpressions-1"></span><h3 class="section">3.5 Back-references and Subexpressions</h3> -<span id="index-subexpression"></span> -<span id="index-back_002dreference"></span> - -<p>The back-reference ‘<samp>\<var>n</var></samp>’, -where <var>n</var> is a single nonzero digit, matches -the substring previously matched by the <var>n</var>th parenthesized subexpression +<h3 class="section" id="Back_002dreferences-and-Subexpressions-1"><span>3.5 Back-references and Subexpressions<a class="copiable-link" href="#Back_002dreferences-and-Subexpressions-1"> ¶</a></span></h3> +<a class="index-entry-id" id="index-subexpression"></a> +<a class="index-entry-id" id="index-back_002dreference"></a> + +<p>The back-reference ‘<samp class="samp">\<var class="var">n</var></samp>’, +where <var class="var">n</var> is a single nonzero digit, matches +the substring previously matched by the <var class="var">n</var>th parenthesized subexpression of the regular expression. -For example, ‘<samp>(a)\1</samp>’ matches ‘<samp>aa</samp>’. +For example, ‘<samp class="samp">(a)\1</samp>’ matches ‘<samp class="samp">aa</samp>’. If the parenthesized subexpression does not participate in the match, the back-reference makes the whole match fail; -for example, ‘<samp>(a)*\1</samp>’ fails to match ‘<samp>a</samp>’. +for example, ‘<samp class="samp">(a)*\1</samp>’ fails to match ‘<samp class="samp">a</samp>’. If the parenthesized subexpression matches more than one substring, the back-reference refers to the last matched substring; -for example, ‘<samp>^(ab*)*\1$</samp>’ matches ‘<samp>ababbabb</samp>’ but not ‘<samp>ababbab</samp>’. +for example, ‘<samp class="samp">^(ab*)*\1$</samp>’ matches ‘<samp class="samp">ababbabb</samp>’ but not ‘<samp class="samp">ababbab</samp>’. When multiple regular expressions are given with -<samp>-e</samp> or from a file (‘<samp>-f <var>file</var></samp>’), +<samp class="option">-e</samp> or from a file (‘<samp class="samp">-f <var class="var">file</var></samp>’), back-references are local to each expression. </p> -<p>See <a href="Known-Bugs.html">Known Bugs</a>, for some known problems with back-references. +<p>See <a class="xref" href="Known-Bugs.html">Known Bugs</a>, for some known problems with back-references. </p> </div>
