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

/
/

Test String

Code Generator

Language

Generated Code

use strict; my $str = 'top - 11:41:04 up 21 min, 1 user, load average: 0.00, 0.01, 0.07 Tasks: 86 total, 1 running, 85 sleeping, 0 stopped, 0 zombie %Cpu(s): 4.7 us, 2.2 sy, 0.5 ni, 92.0 id, 0.3 wa, 0.0 hi, 0.3 si, KiB Mem: 501692 total, 475348 used, 26344 free, 13032 buffers KiB Swap: 0 total, 0 used, 0 free. 281204 cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ 1 root 20 0 33632 2940 1468 S 0.0 0.6 0:01.87 2 root 20 0 0 0 0 S 0.0 0.0 0:00.01 ... 17836 www-data 20 0 287448 6708 2424 S 0.0 1.3 0:00.02 17914 vagrant 20 0 23528 1396 1048 R 0.0 0.3 0:00.00'; my $regex = qr/Tasks: (\d+) total, (\d+) running, (\d+) sleeping, (\d+) stopped, (\d+) zombie/p; if ( $str =~ /$regex/ ) { 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