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

# coding=utf8 # the above tag defines encoding for this document and is for Python 2.x compatibility import re regex = r"(?<timestamp>\d{4}\/\d{2}\/\d{2} \d{2}:\d{2}:\d{2}) \[(?<level>.*)\]\ (?<process_id>\d*)#(?<thread_id>\d*): (?<message>.*)" test_str = ("2022/03/02 08:28:02 [notice] 6888#0: using the \"epoll\" event method\n" "2022/03/02 08:28:02 [notice] 6888#0: start worker processes\n" "2022/03/02 08:28:02 [notice] 6888#0: start worker process 7234\n" "2022/03/02 08:28:02 [notice] 6888#0: start worker process 7235\n" "2022/03/02 08:28:02 [notice] 6888#0: start worker process 7236\n" "2022/03/02 08:28:02 [notice] 6888#0: start worker process 7237\n" "2022/03/02 08:28:02 [notice] 6888#0: start worker process 7238\n" "2022/03/02 08:28:02 [notice] 6888#0: start worker process 7239\n" "2022/03/02 08:28:02 [notice] 6888#0: start worker process 7240\n" "2022/03/02 08:28:02 [notice] 6888#0: start worker process 7241\n" "2022/03/02 08:28:02 [notice] 6888#0: signal 17 (SIGCHLD) received from 6943\n" "2022/03/02 08:28:02 [notice] 6888#0: worker process 6942 exited with code 0\n" "2022/03/02 08:28:02 [notice] 6888#0: worker process 6943 exited with code 0\n" "2022/03/02 08:28:02 [notice] 6888#0: worker process 6944 exited with code 0\n" "2022/03/02 08:28:02 [notice] 6888#0: worker process 6945 exited with code 0\n" "2022/03/02 08:28:02 [notice] 6888#0: signal 29 (SIGIO) received\n" "2022/03/02 08:28:02 [notice] 6888#0: signal 17 (SIGCHLD) received from 6942\n" "2022/03/02 08:28:02 [notice] 6888#0: signal 17 (SIGCHLD) received from 6946\n" "2022/03/02 08:28:02 [notice] 6888#0: worker process 6940 exited with code 0\n" "2022/03/02 08:28:02 [notice] 6888#0: worker process 6946 exited with code 0\n" "2022/03/02 08:28:02 [notice] 6888#0: signal 29 (SIGIO) received\n" "2022/03/02 08:28:02 [notice] 6888#0: signal 17 (SIGCHLD) received from 6939\n" "2022/03/02 08:28:02 [notice] 6888#0: worker process 6939 exited with code 0\n" "2022/03/02 08:28:02 [notice] 6888#0: signal 29 (SIGIO) received\n" "2022/03/02 08:28:02 [notice] 6888#0: signal 17 (SIGCHLD) received from 6941\n" "2022/03/02 08:28:02 [notice] 6888#0: worker process 6941 exited with code 0\n" "2022/03/02 08:28:02 [notice] 6888#0: signal 29 (SIGIO) received") 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