Regular Expressions 101

Save & Share

  • Regex Version: ver. 2
  • Update Regex
    ctrl+⇧+s
  • Save new Regex
    ctrl+s
  • Add to Community Library

Flavor

  • PCRE2 (PHP >=7.3)
  • PCRE (PHP <7.3)
  • ECMAScript (JavaScript)
  • Python
  • Golang
  • Java 8
  • .NET 7.0 (C#)
  • Rust
  • Regex Flavor Guide

Function

  • Match
  • Substitution
  • List
  • Unit Tests

Tools

Sponsors
There are currently no sponsors. Become a sponsor today!
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

/
/
gmx

Test String

Code Generator

Language

Generated Code

use strict; my $str = '2016-01-29 18:19:54 local1.info server.domain.com 2016-01-29: 11:19:54 MST UNKNOWN UNKNOWN FOO "BAR BAZ" UNKNOWN UNKNOWN UNKNOWN EMAIL@EXAMPLE.COM PROFILE_CHANGE ProfileChangeProcessor A 2016-01-29 18:20:25 local4.info server.domain.com 2016-01-29: 11:20:25 MST UNKNOWN UNKNOWN "F B" BAZ ABC12345 GP SOME_UID EMAIL@EXAMPLE.COM EVENT_FROM_SOME_PROCESS UNKNOWN UNKNOWN 2016-01-29 18:23:10 local1.info server.domain.com 2016-01-29: 11:23:10 MST UNKNOWN UNKNOWN FOO BAR UNKNOWN UNKNOWN UNKNOWN EMAIL@EXAMPLE.COM SOME_CHANGE ProfileChangeProcessor AP 2016-01-29 18:26:24 local1.info server.domain.com 2016-01-29: 11:26:24 MST UNKNOWN EMAIL@EXAMPLE.COM FOO "B\'Baz" UNKNOWN UNKNOWN UNKNOWN SOME_CHANGE ProfileChangeProcessor O 2016-01-29 18:26:55 local1.info server.domain.com 2016-01-29: 11:26:55 MST UNKNOWN EMAIL@EXAMPLE.COM "FOO OR BAR" BAZ SXR12646 GP UNKNOWN SOME_CHANGE ProfileChangeProcessor M'; my $regex = qr/^\s* # date (?<date>\d{4}-\d{2}-\d{2}\s+\d{2}:\d{2}:\d{2}) # facility.severity \s(?<facility>\S+)\.(?<severity>\S+) # server \s(?<server>\S*) # date \s(?<otherDate>\d{4}-\d{2}-\d{2}:\s\d{2}:\d{2}:\d{2}) # time zone \s(?<timeZone>\S*) # ip address \s(?<ip>\S*) # legacy email address \s(?<legacyEmailAddress>\S*) # first name \s(?|"(?<firstName>[^"\n]+)"|(?<firstName>\S*)) # last name \s(?|"(?<lastName>[^"\n]+)"|(?<lastName>\S*)) # account number \s(?<account>\S*) # program code \s(?<programCode>\S*) # uid \s(?<uid>\S*) # email address \s(?<emailAddress>\S*) # event type \s(?<eventType>\S*) # source \s(?<source>\S*) # category \s(?<category>\S*) \s*$/mxp; 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