CVSROOT: /web/grep Module name: grep Changes by: Karl Berry <karl> 09/05/24 18:43:01
Index: manual/html_node/Regular-Expressions.html =================================================================== RCS file: manual/html_node/Regular-Expressions.html diff -N manual/html_node/Regular-Expressions.html --- /dev/null 1 Jan 1970 00:00:00 -0000 +++ manual/html_node/Regular-Expressions.html 24 May 2009 18:42:59 -0000 1.1 @@ -0,0 +1,72 @@ +<html lang="en"> +<head> +<title>Regular Expressions - 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="prev" href="Invoking.html#Invoking" title="Invoking"> +<link rel="next" href="Usage.html#Usage" title="Usage"> +<link href="http://www.gnu.org/software/texinfo/"; 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 } + span.sc { font-variant:small-caps } + span.roman { font-family:serif; font-weight:normal; } + span.sansserif { font-family:sans-serif; font-weight:normal; } +--></style> +</head> +<body> +<div class="node"> +<a name="Regular-Expressions"></a> +<p> +Next: <a rel="next" accesskey="n" href="Usage.html#Usage">Usage</a>, +Previous: <a rel="previous" accesskey="p" href="Invoking.html#Invoking">Invoking</a>, +Up: <a rel="up" accesskey="u" href="index.html#Top">Top</a> +<hr> +</div> + +<h2 class="chapter">3 Regular Expressions</h2> + +<p><a name="index-regular-expressions-178"></a> +A <dfn>regular expression</dfn> is a pattern that describes a set of strings. +Regular expressions are constructed analogously to arithmetic expressions, +by using various operators to combine smaller expressions. +<samp><span class="command">grep</span></samp> understands +two different versions of regular expression syntax: +“basic”(BRE) and “extended”(ERE). +In <span class="sc">gnu</span> <samp><span class="command">grep</span></samp>, +there is no difference in available functionality using either syntax. +In other implementations, basic regular expressions are less powerful. +The following description applies to extended regular expressions; +differences for basic regular expressions are summarized afterwards. + +<ul class="menu"> +<li><a accesskey="1" href="Fundamental-Structure.html#Fundamental-Structure">Fundamental Structure</a> +<li><a accesskey="2" href="Character-Classes-and-Bracket-Expressions.html#Character-Classes-and-Bracket-Expressions">Character Classes and Bracket Expressions</a> +<li><a accesskey="3" href="The-Backslash-Character-and-Special-Expressions.html#The-Backslash-Character-and-Special-Expressions">The Backslash Character and Special Expressions</a> +<li><a accesskey="4" href="Anchoring.html#Anchoring">Anchoring</a> +<li><a accesskey="5" href="Back_002dreferences-and-Subexpressions.html#Back_002dreferences-and-Subexpressions">Back-references and Subexpressions</a> +<li><a accesskey="6" href="Basic-vs-Extended.html#Basic-vs-Extended">Basic vs Extended</a> +</ul> + + </body></html> +
