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"^\[\S+\s+\S+\s+\S+\s+\S+\s+\S+\] \[(\S*:)?(?:error|info)\] (\[pid \d+(:tid \d+)?\] )?\[client (\S+)\] (\w+: )?File does not exist\:" test_str = ("[Tue Feb 09 05:02:22.769263 2021] [core:error] [pid 83886:tid 140340187059968] [client 192.168.1.133:53478] AH00128: File does not exist: /var/www/vhosts/example.com/httpdocs/test.png\n" "[Tue Feb 09 05:02:23.986502 2021] [core:info] [pid 83885:tid 140340270987008] [client 192.168.1.133:53482] AH00128: File does not exist: /var/www/vhosts/example.com/httpdocs/test.png\n" "[Tue Feb 09 05:02:24.480283 2021] [core:info] [pid 83885:tid 140340262594304] [client 192.168.1.133:53486] AH00128: File does not exist: /var/www/vhosts/example.com/httpdocs/test.png\n" "[Tue Feb 09 05:02:24.882395 2021] [core:info] [pid 83886:tid 140340170274560] [client 192.168.1.133:53490] AH00128: File does not exist: /var/www/vhosts/example.com/httpdocs/test.png\n" "[Tue Feb 09 05:02:25.224595 2021] [core:info] [pid 83884:tid 140340262594304] [client 192.168.1.133:53494] AH00128: File does not exist: /var/www/vhosts/example.com/httpdocs/test.png") 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