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

/
/
gm

Test String

Code Generator

Language

Generated Code

use strict; my $str = 'Sample Log4j strings: ${JNDI:LDAP:// ${JNDI:LDAPS:// ${JNDI:RMI:// ${JNDI:DNS:// ${JNDI:NIS:// ${JNDI:IIOP:// ${JNDI:CORBA:// ${JNDI:NDS:// ${JNDI:HTTPS:// ${JNDI:HTTP:// $ { JNDI :LDAPS:// $ { JNDI :LDAPS:// ${jNDi:l%252564ap:// JNDI = %6A%6E%64%69 jndi = %4A%4E%44%49 Multi-encoding log4j strings (without spaces): %24%7B%6A%6E%64%69%3A%2F %2524%257B%256A%256E%2564%2569%253A %2524%257B%256A%256E%2564%2569%253A%252F %252524%25257B%25256A%25256E%252564%252569%25253A%25252F Multi-URL Encoded string characters: (?i) (%(25){0,}20|\\s)* (%(25){0,}24|$) (%(25){0,}20|\\s)* (%(25){0,}7B|{) (%(25){0,}20|\\s)* (%(25){0,}(6A|4A)|J) (%(25){0,}(6E|4E)|N) (%(25){0,}(64|44)|D) (%(25){0,}(69|49)|I) (%(25){0,}20|\\s)* (%(25){0,}3A|:) (%(25){0,}2F|\\/) [\\w\\%]+ (%(25){0,}3A|:) (%(25){0,}2F|\\/) '; my $regex = qr/(?i)(%(25){0,}20|\s)*(%(25){0,}24|\$)(%(25){0,}20|\s)*(%(25){0,}7B|{)(%(25){0,}20|\s)*(%(25){0,}(6A|4A)|J)(%(25){0,}(6E|4E)|N)(%(25){0,}(64|44)|D)(%(25){0,}(69|49)|I)(%(25){0,}20|\s)*(%(25){0,}3A|:)[\w\%]+(%(25){1,}3A|:)(%(25){1,}2F|\/)[^\n]+/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