Regular Expressions 101

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An explanation of your regex will be automatically generated as you type.
Detailed match information will be displayed here automatically.
  • All Tokens
  • Common Tokens
  • General Tokens
  • Anchors
  • Meta Sequences
  • Quantifiers
  • Group Constructs
  • Character Classes
  • Flags/Modifiers
  • Substitution
  • A single character of: a, b or c
    [abc]
  • A character except: a, b or c
    [^abc]
  • A character in the range: a-z
    [a-z]
  • A character not in the range: a-z
    [^a-z]
  • A character in the range: a-z or A-Z
    [a-zA-Z]
  • Any single character
    .
  • Alternate - match either a or b
    a|b
  • Any whitespace character
    \s
  • Any non-whitespace character
    \S
  • Any digit
    \d
  • Any non-digit
    \D
  • Any word character
    \w
  • Any non-word character
    \W
  • Non-capturing group
    (?:...)
  • Capturing group
    (...)
  • Zero or one of a
    a?
  • Zero or more of a
    a*
  • One or more of a
    a+
  • Exactly 3 of a
    a{3}
  • 3 or more of a
    a{3,}
  • Between 3 and 6 of a
    a{3,6}
  • Start of string
    ^
  • End of string
    $
  • A word boundary
    \b
  • Non-word boundary
    \B

Regular Expression
No Match

r"""
"""
gm

Test String

Code Generator

Language

Generated Code

use strict; my $str = '190.2.7.178 - - [21/Dec/2011:05:47:03 +0000] "GET /gnu3/index.php?doc=../../../../../../../proc/self/environ%00 HTTP/1.1" 404 273 "-" "<?php system(\\"id\\"); ?>" 190.2.7.178 - - [21/Dec/2011:05:47:04 +0000] "GET /gnu/index.php?doc=../../../../../../../proc/self/environ%00 HTTP/1.1" 404 271 "-" "<?php system(\\"id\\"); ?>" 190.2.7.178 - - [21/Dec/2011:05:47:04 +0000] "GET /phpgwapi/setup/tables_update.inc.php?appdir=../../../../../../../proc/self/environ%00 HTTP/1.1" 404 286 "-" "<?php system(\\"id\\"); ?>" 190.2.7.178 - - [21/Dec/2011:05:47:05 +0000] "GET /forum/install.php?phpbb_root_dir=../../../../../../../proc/self/environ%00 HTTP/1.1" 404 274 "-" "<?php system(\\"id\\"); ?>" 190.2.7.178 - - [21/Dec/2011:05:47:06 +0000] "GET /includes/calendar.php?phpc_root_path=../../../../../../../proc/self/environ%00 HTTP/1.1" 404 275 "-" "<?php system(\\"id\\"); ?>" 190.2.7.178 - - [21/Dec/2011:05:47:06 +0000] "GET /includes/setup.php?phpc_root_path=../../../../../../../proc/self/environ%00 HTTP/1.1" 404 273 "-" "<?php system(\\"id\\"); ?>" 190.2.7.178 - - [21/Dec/2011:05:47:07 +0000] "GET /inc/authform.inc.php?path_pre=../../../../../../../proc/self/environ%00 HTTP/1.1" 404 275 "-" "<?php system(\\"id\\"); ?>" 190.2.7.178 - - [21/Dec/2011:05:47:07 +0000] "GET /include/authform.inc.php?path_pre=../../../../../../../proc/self/environ%00 HTTP/1.1" 404 278 "-" "<?php system(\\"id\\"); ?>" 190.2.7.178 - - [21/Dec/2011:05:47:08 +0000] "GET /index.php?nic=../../../../../../../proc/self/environ%00 HTTP/1.1" 200 4399 "-" "<?php system(\\"id\\"); ?>" 190.2.7.178 - - [21/Dec/2011:05:47:11 +0000] "GET /index.php?sec=../../../../../../../proc/self/environ%00 HTTP/1.1" 200 4399 "-" "<?php system(\\"id\\"); ?>" 123.125.71.79 - - [28/Apr/2012:08:12:57 +0100] "GET /robots.txt HTTP/1.1" 404 268 "-" "Mozilla/5.0 (compatible; Baiduspider/2.0; +http://www.baidu.com/search/spider.html)" 157.56.95.126 - - [28/Apr/2012:10:23:02 +0100] "GET /robots.txt HTTP/1.1" 404 268 "-" "msnbot/2.0b (+http://search.msn.com/msnbot.htm)" 157.56.95.126 - - [28/Apr/2012:10:23:02 +0100] "GET / HTTP/1.1" 200 4399 "-" "msnbot/2.0b (+http://search.msn.com/msnbot.htm)" 110.75.173.193 - - [28/Apr/2012:11:57:26 +0100] "GET / HTTP/1.1" 200 4399 "-" "Yahoo! Slurp China"'; my $regex = qr/(?x)^ (?P<remote_host>\S+) \s+ # host %h \S+ \s+ # indent %l (unused) (?P<remote_user>\S+) \s+ # user %u \[(?P<time_received>.*?)\] \s+ # time %t "(?P<request>.*?)" \s+ # request "%r" (?P<status>[0-9]+) \s+ # status %>s (?P<response_bytes_clf>\S+) (?:\s+ # size %b (careful, can be '-') "(?P<referrer>[^"?\s]*[^"]*)" \s+ # referrer "%{Referer}i" "(?P<user_agent>.*? )" (?:\s+ # user agent "%{User-agent}i" "[^"]*" )?)? # optional argument (unused) $/mp; if ( $str =~ /$regex/g ) { print "Whole match is ${^MATCH} and its start/end positions can be obtained via \$-[0] and \$+[0]\n"; # print "Capture Group 1 is $1 and its start/end positions can be obtained via \$-[1] and \$+[1]\n"; # print "Capture Group 2 is $2 ... and so on\n"; } # ${^POSTMATCH} and ${^PREMATCH} are also available with the use of '/p' # Named capture groups can be called via $+{name}

Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Perl, please visit: http://perldoc.perl.org/perlre.html