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

Substitution

Processing...

Code Generator

Language

Generated Code

use strict; my $str = 'wsrep_provider_options=\'gmcast.segment=0; ist.recv_addr=tcp://db7; ist.recv_bind=tcp://0.0.0.0; socket.ssl_cert=/etc/mysql/wsrep/ssl/gmnode.pem; socket.ssl_key=/etc/mysql/wsrep/ssl/gmnode.key; socket.ssl_ca=/etc/mysql/wsrep/ssl/gmca.pem\' wsrep_provider_options=\'gmcast.segment=0; ist.recv_addr=tcp://db7; ist.recv_bind=tcp://0.0.0.0; socket.ssl_cert=/etc/mysql/wsrep/ssl/gmnode.pem; socket.ssl_key=/etc/mysql/wsrep/ssl/gmnode.key; socket.ssl_ca=/etc/mysql/wsrep/ssl/gmca.pem; gcache.size=4G\' wsrep_provider_options=\'gcache.size=4G; gmcast.segment=0; ist.recv_addr=tcp://db7; ist.recv_bind=tcp://0.0.0.0; socket.ssl_cert=/etc/mysql/wsrep/ssl/gmnode.pem; socket.ssl_key=/etc/mysql/wsrep/ssl/gmnode.key; socket.ssl_ca=/etc/mysql/wsrep/ssl/gmca.pem\''; my $regex = qr/^(wsrep_provider_options(?!.*\bgcache.size\b).*)('$)/mp; my $subst = '\\1; gcache.size=4G\\2'; my $result = $str =~ s/$regex/$subst/rg; print "The result of the substitution is' $result\n";

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