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Changes to manual/html_node/Character-Classes-and-Bracket-Expressions.ht
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From: |
Karl Berry |
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Subject: |
Changes to manual/html_node/Character-Classes-and-Bracket-Expressions.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/Character-Classes-and-Bracket-Expressions.html
===================================================================
RCS file: manual/html_node/Character-Classes-and-Bracket-Expressions.html
diff -N manual/html_node/Character-Classes-and-Bracket-Expressions.html
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+++ manual/html_node/Character-Classes-and-Bracket-Expressions.html 24 May
2009 18:42:58 -0000 1.1
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+<html lang="en">
+<head>
+<title>Character Classes and Bracket Expressions - GNU Grep 2.5.4</title>
+<meta http-equiv="Content-Type" content="text/html">
+<meta name="description" content="GNU Grep 2.5.4">
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+<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="Fundamental-Structure.html#Fundamental-Structure"
title="Fundamental Structure">
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href="The-Backslash-Character-and-Special-Expressions.html#The-Backslash-Character-and-Special-Expressions"
title="The Backslash Character and Special Expressions">
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+<div class="node">
+<a name="Character-Classes-and-Bracket-Expressions"></a>
+<p>
+Next: <a rel="next" accesskey="n"
href="The-Backslash-Character-and-Special-Expressions.html#The-Backslash-Character-and-Special-Expressions">The
Backslash Character and Special Expressions</a>,
+Previous: <a rel="previous" accesskey="p"
href="Fundamental-Structure.html#Fundamental-Structure">Fundamental
Structure</a>,
+Up: <a rel="up" accesskey="u"
href="Regular-Expressions.html#Regular-Expressions">Regular Expressions</a>
+<hr>
+</div>
+
+<h3 class="section">3.2 Character Classes and Bracket Expressions</h3>
+
+<p><a name="index-bracket-expression-203"></a><a
name="index-character-class-204"></a>A <dfn>bracket expression</dfn> is a list
of characters enclosed by ‘<samp><span
class="samp">[</span></samp>’ and
+‘<samp><span class="samp">]</span></samp>’.
+It matches any single character in that list;
+if the first character of the list is the caret ‘<samp><span
class="samp">^</span></samp>’,
+then it matches any character <strong>not</strong> in the list.
+For example, the regular expression
+‘<samp><span class="samp">[0123456789]</span></samp>’ matches any
single digit.
+
+ <p><a name="index-range-expression-205"></a>Within a bracket expression, a
<dfn>range expression</dfn> consists of two
+characters separated by a hyphen.
+It matches any single character that
+sorts between the two characters, inclusive, using the locale's
+collating sequence and character set.
+For example, in the default C
+locale, ‘<samp><span class="samp">[a-d]</span></samp>’ is
equivalent to ‘<samp><span class="samp">[abcd]</span></samp>’.
+Many locales sort
+characters in dictionary order, and in these locales ‘<samp><span
class="samp">[a-d]</span></samp>’ is
+typically not equivalent to ‘<samp><span
class="samp">[abcd]</span></samp>’;
+it might be equivalent to ‘<samp><span
class="samp">[aBbCcDd]</span></samp>’, for example.
+To obtain the traditional interpretation
+of bracket expressions, you can use the ‘<samp><span
class="samp">C</span></samp>’ locale by setting the
+<samp><span class="env">LC_ALL</span></samp> environment variable to the value
‘<samp><span class="samp">C</span></samp>’.
+
+ <p>Finally, certain named classes of characters are predefined within
+bracket expressions, as follows.
+Their interpretation depends on the <code>LC_CTYPE</code> locale;
+the interpretation below is that of the ‘<samp><span
class="samp">C</span></samp>’ locale,
+which is the default if no <code>LC_CTYPE</code> locale is specified.
+
+ <p><a name="index-classes-of-characters-206"></a><a
name="index-character-classes-207"></a>
+ <dl>
+<dt>‘<samp><span class="samp">[:alnum:]</span></samp>’<dd><a
name="index-alnum-_0040r_007bcharacter-class_007d-208"></a><a
name="index-alphanumeric-characters-209"></a>Alphanumeric characters:
+‘<samp><span class="samp">[:alpha:]</span></samp>’ and
‘<samp><span class="samp">[:digit:]</span></samp>’.
+
+ <br><dt>‘<samp><span
class="samp">[:alpha:]</span></samp>’<dd><a
name="index-alpha-_0040r_007bcharacter-class_007d-210"></a><a
name="index-alphabetic-characters-211"></a>Alphabetic characters:
+‘<samp><span class="samp">[:lower:]</span></samp>’ and
‘<samp><span class="samp">[:upper:]</span></samp>’.
+
+ <br><dt>‘<samp><span
class="samp">[:blank:]</span></samp>’<dd><a
name="index-blank-_0040r_007bcharacter-class_007d-212"></a><a
name="index-blank-characters-213"></a>Blank characters:
+space and tab.
+
+ <br><dt>‘<samp><span
class="samp">[:cntrl:]</span></samp>’<dd><a
name="index-cntrl-_0040r_007bcharacter-class_007d-214"></a><a
name="index-control-characters-215"></a>Control characters.
+In <span class="sc">ascii</span>, these characters have octal codes 000
+through 037, and 177 (<code>DEL</code>).
+In other character sets, these are
+the equivalent characters, if any.
+
+ <br><dt>‘<samp><span
class="samp">[:digit:]</span></samp>’<dd><a
name="index-digit-_0040r_007bcharacter-class_007d-216"></a><a
name="index-digit-characters-217"></a><a
name="index-numeric-characters-218"></a>Digits: <code>0 1 2 3 4 5 6 7 8
9</code>.
+
+ <br><dt>‘<samp><span
class="samp">[:graph:]</span></samp>’<dd><a
name="index-graph-_0040r_007bcharacter-class_007d-219"></a><a
name="index-graphic-characters-220"></a>Graphical characters:
+‘<samp><span class="samp">[:alnum:]</span></samp>’ and
‘<samp><span class="samp">[:punct:]</span></samp>’.
+
+ <br><dt>‘<samp><span
class="samp">[:lower:]</span></samp>’<dd><a
name="index-lower-_0040r_007bcharacter-class_007d-221"></a><a
name="index-lower_002dcase-letters-222"></a>Lower-case letters:
+<code>a b c d e f g h i j k l m n o p q r s t u v w x y z</code>.
+
+ <br><dt>‘<samp><span
class="samp">[:print:]</span></samp>’<dd><a
name="index-print-_0040r_007bcharacter-class_007d-223"></a><a
name="index-printable-characters-224"></a>Printable characters:
+‘<samp><span class="samp">[:alnum:]</span></samp>’,
‘<samp><span class="samp">[:punct:]</span></samp>’, and space.
+
+ <br><dt>‘<samp><span
class="samp">[:punct:]</span></samp>’<dd><a
name="index-punct-_0040r_007bcharacter-class_007d-225"></a><a
name="index-punctuation-characters-226"></a>Punctuation characters:
+<code>! " # $ % & ' ( ) * + , - . / : ; < = > ? @ [ \ ] ^ _ ` { | }
~</code>.
+
+ <br><dt>‘<samp><span
class="samp">[:space:]</span></samp>’<dd><a
name="index-space-_0040r_007bcharacter-class_007d-227"></a><a
name="index-space-characters-228"></a><a
name="index-whitespace-characters-229"></a>Space characters:
+tab, newline, vertical tab, form feed, carriage return, and space.
+
+ <br><dt>‘<samp><span
class="samp">[:upper:]</span></samp>’<dd><a
name="index-upper-_0040r_007bcharacter-class_007d-230"></a><a
name="index-upper_002dcase-letters-231"></a>Upper-case letters:
+<code>A B C D E F G H I J K L M N O P Q R S T U V W X Y Z</code>.
+
+ <br><dt>‘<samp><span
class="samp">[:xdigit:]</span></samp>’<dd><a
name="index-xdigit-_0040r_007bcharacter-class_007d-232"></a><a
name="index-xdigit-class-233"></a><a
name="index-hexadecimal-digits-234"></a>Hexadecimal digits:
+<code>0 1 2 3 4 5 6 7 8 9 A B C D E F a b c d e f</code>.
+
+ </dl>
+ For example, ‘<samp><span
class="samp">[[:alnum:]]</span></samp>’ means ‘<samp><span
class="samp">[0-9A-Za-z]</span></samp>’, except the latter
+depends upon the ‘<samp><span class="samp">C</span></samp>’ locale
and the <span class="sc">ascii</span> character
+encoding, whereas the former is independent of locale and character set.
+(Note that the brackets in these class names are
+part of the symbolic names, and must be included in addition to
+the brackets delimiting the bracket expression.)
+
+ <p>Most meta-characters lose their special meaning inside bracket
expressions.
+
+ <dl>
+<dt>‘<samp><span class="samp">]</span></samp>’<dd>ends the bracket
expression if it's not the first list item.
+So, if you want to make the ‘<samp><span
class="samp">]</span></samp>’ character a list item,
+you must put it first.
+
+ <br><dt>‘<samp><span
class="samp">[.</span></samp>’<dd>represents the open collating symbol.
+
+ <br><dt>‘<samp><span
class="samp">.]</span></samp>’<dd>represents the close collating symbol.
+
+ <br><dt>‘<samp><span
class="samp">[=</span></samp>’<dd>represents the open equivalence class.
+
+ <br><dt>‘<samp><span
class="samp">=]</span></samp>’<dd>represents the close equivalence class.
+
+ <br><dt>‘<samp><span
class="samp">[:</span></samp>’<dd>represents the open character class
symbol, and should be followed by a valid character class name.
+
+ <br><dt>‘<samp><span
class="samp">:]</span></samp>’<dd>represents the close character class
symbol.
+
+ <br><dt>‘<samp><span
class="samp">-</span></samp>’<dd>represents the range if it's not first
or last in a list or the ending point
+of a range.
+
+ <br><dt>‘<samp><span
class="samp">^</span></samp>’<dd>represents the characters not in the
list.
+If you want to make the ‘<samp><span class="samp">^</span></samp>’
+character a list item, place it anywhere but first.
+
+ </dl>
+
+ </body></html>
+
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