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Changes to manual/html_node/Basic-vs-Extended.html
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From: |
Karl Berry |
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Subject: |
Changes to manual/html_node/Basic-vs-Extended.html |
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Date: |
Sun, 24 May 2009 18:43:06 +0000 |
CVSROOT: /web/grep
Module name: grep
Changes by: Karl Berry <karl> 09/05/24 18:43:01
Index: manual/html_node/Basic-vs-Extended.html
===================================================================
RCS file: manual/html_node/Basic-vs-Extended.html
diff -N manual/html_node/Basic-vs-Extended.html
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ manual/html_node/Basic-vs-Extended.html 24 May 2009 18:42:58 -0000
1.1
@@ -0,0 +1,69 @@
+<html lang="en">
+<head>
+<title>Basic vs Extended - 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="Back_002dreferences-and-Subexpressions.html#Back_002dreferences-and-Subexpressions"
title="Back-references and Subexpressions">
+<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''.
+ -->
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+<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="Basic-vs-Extended"></a>
+<p>
+Previous: <a rel="previous" accesskey="p"
href="Back_002dreferences-and-Subexpressions.html#Back_002dreferences-and-Subexpressions">Back-references
and Subexpressions</a>,
+Up: <a rel="up" accesskey="u"
href="Regular-Expressions.html#Regular-Expressions">Regular Expressions</a>
+<hr>
+</div>
+
+<h3 class="section">3.6 Basic vs Extended Regular Expressions</h3>
+
+<p><a name="index-basic-regular-expressions-239"></a>
+In basic regular expressions the meta-characters ‘<samp><span
class="samp">?</span></samp>’, ‘<samp><span
class="samp">+</span></samp>’,
+‘<samp><span class="samp">{</span></samp>’, ‘<samp><span
class="samp">|</span></samp>’, ‘<samp><span
class="samp">(</span></samp>’, and ‘<samp><span
class="samp">)</span></samp>’ lose their special meaning;
+instead use the backslashed versions ‘<samp><span
class="samp">\?</span></samp>’, ‘<samp><span
class="samp">\+</span></samp>’, ‘<samp><span
class="samp">\{</span></samp>’,
+‘<samp><span class="samp">\|</span></samp>’, ‘<samp><span
class="samp">\(</span></samp>’, and ‘<samp><span
class="samp">\)</span></samp>’.
+
+ <p><a name="index-interval-specifications-240"></a>Traditional <samp><span
class="command">egrep</span></samp> did not support the ‘<samp><span
class="samp">{</span></samp>’ meta-character,
+and some <samp><span class="command">egrep</span></samp> implementations
support ‘<samp><span class="samp">\{</span></samp>’ instead, so
+portable scripts should avoid ‘<samp><span
class="samp">{</span></samp>’ in ‘<samp><span class="samp">grep
-E</span></samp>’ patterns and
+should use ‘<samp><span class="samp">[{]</span></samp>’ to match a
literal ‘<samp><span class="samp">{</span></samp>’.
+
+ <p><span class="sc">gnu</span> <samp><span class="command">grep
-E</span></samp> attempts to support traditional usage by
+assuming that ‘<samp><span class="samp">{</span></samp>’ is not
special if it would be the start of an
+invalid interval specification.
+For example, the command
+‘<samp><span class="samp">grep -E '{1'</span></samp>’ searches for
the two-character string ‘<samp><span class="samp">{1</span></samp>’
+instead of reporting a syntax error in the regular expression.
+<span class="sc">posix.2</span> allows this behavior as an extension, but
portable scripts
+should avoid it.
+
+ </body></html>
+
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