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"core\.\d*" test_str = ("303488 -rw------- 1 oagmgr oinstall 596971520 May 10 15:54 core.10081 \n" "271392 -rw------- 1 oagmgr oinstall 543047680 Aug 16 09:59 core.1708 \n" "310616 -rw------- 1 oagmgr oinstall 621223936 Jul 29 09:05 core.21813 \n" "261296 -rw------- 1 oagmgr oinstall 524054528 Sep 4 08:29 core.25532 \n" "292500 -rw------- 1 oagmgr oinstall 469028864 Jun 25 19:45 core.32008 \n" "291580 -rw------- 1 oagmgr oinstall 600080384 Jul 11 22:08 core.7981 \n" "365072 -rw------- 1 oagmgr oinstall 484425728 Jun 2 14:08 core.8238 \n\n\n" " 24 -rw-r--r-- 1 oagmgr oinstall 23606 Aug 16 09:59 hs_err_pid1708.log \n" " 24 -rw-r--r-- 1 oagmgr oinstall 23436 Apr 4 21:19 hs_err_pid18984.log \n" " 24 -rw-r--r-- 1 oagmgr oinstall 23421 Sep 4 08:29 hs_err_pid25532.log \n" " 24 -rw-r--r-- 1 oagmgr oinstall 23497 Jul 11 22:08 hs_err_pid7981.log \n" " 24 -rw-r--r-- 1 oagmgr oinstall 24080 Jun 2 14:08 hs_err_pid8238.log ") 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