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

`
`
mg

Test String

Code Generator

Generated Code

# coding=utf8 # the above tag defines encoding for this document and is for Python 2.x compatibility import re regex = r"(?P<time>\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2},\d{0,3}) (?P<message>fail2ban.*(?P<gid>\[\d*\]: )(?P<level>[A-Z]{4,7}) .*)" test_str = ("2020-05-11 06:25:02,732 fail2ban.server [879]: INFO rollover performed on /var/log/fail2ban.log\n" "2020-05-08 01:34:33,079 fail2ban.filter [16566]: INFO [sshd] Found 1.1.1.1 - 2020-05-08 01:34:33\n" "2020-05-09 04:02:31,316 fail2ban.actions [16566]: NOTICE [sshd] Ban 1.0.0.1\n" "2020-05-23 00:09:06,355 fail2ban.server [9474]: INFO Reload jail GHOST\n" "2020-05-23 00:09:06,355 fail2ban.filter [9474]: INFO Removed logfile: '/opt/logs/ghost/https___nonsense_fyi_production.log'\n" "2020-05-23 00:09:07,902 fail2ban.actions [9474]: NOTICE [GHOST] Flush ticket(s) with iptables-multiport\n" "2020-05-23 00:09:07,902 fail2ban.actions [9474]: NOTICE [GHOST] Flush ticket(s) with iptables-allports\n" "2020-05-23 00:09:09,699 fail2ban.jail [9474]: INFO Jail 'GHOST' stopped\n" "2020-05-23 00:09:09,701 fail2ban.jail [9474]: INFO Creating new jail 'GHOST'\n" "2020-05-23 00:09:09,701 fail2ban.jail [9474]: INFO Jail 'GHOST' uses pyinotify {}\n" "2020-05-23 00:09:09,706 fail2ban.jail [9474]: INFO Initiated 'pyinotify' backend\n" "2020-05-23 00:09:09,709 fail2ban.filter [9474]: INFO Added logfile: '/opt/logs/ghost/https___nonsense_fyi_production.log' (pos = 14909, hash = 7091b34995f750999f6c605cd6250439a2e0cde7)\n" "2020-05-23 00:09:09,710 fail2ban.filter [9474]: INFO encoding: UTF-8\n" "2020-05-23 00:09:09,711 fail2ban.filter [9474]: INFO maxRetry: 5\n" "2020-05-23 00:09:09,711 fail2ban.filter [9474]: INFO findtime: 300\n" "2020-05-23 00:09:09,712 fail2ban.actions [9474]: INFO banTime: 2592000\n" "2020-05-23 00:09:09,714 fail2ban.jail [9474]: INFO Jail 'GHOST' started\n" "2020-05-23 00:09:09,714 fail2ban.server [9474]: INFO Reload finished.") matches = re.finditer(regex, test_str, re.MULTILINE) for matchNum, match in enumerate(matches, start=1): print ("Match {matchNum} was found at {start}-{end}: {match}".format(matchNum = matchNum, start = match.start(), end = match.end(), match = match.group())) for groupNum in range(0, len(match.groups())): groupNum = groupNum + 1 print ("Group {groupNum} found at {start}-{end}: {group}".format(groupNum = groupNum, start = match.start(groupNum), end = match.end(groupNum), group = match.group(groupNum))) # Note: for Python 2.7 compatibility, use ur"" to prefix the regex and u"" to prefix the test string and substitution.

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 Python, please visit: https://docs.python.org/3/library/re.html