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
  • Match everything enclosed
    (?:...)
  • Capture everything enclosed
    (...)
  • 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

r"
"
gm

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"^(\%.*|Command rejected.*)" test_str = ("**State Acronym: H - Healthy, W - Warning, C - Critical\n" "Resource Usage Max Warning Critical State\n" "----------------------------------------------------------------------------------------------------\n" "RP0 (ok, active) H\n" " Control Processor 29.42% 100% 80% 90% H\n" " DRAM 2840MB(72%) 3938MB 88% 93% H\n" " bootflash 1889MB(69%) 2753MB 70% 90% H\n" "ESP0(ok, active) H\n" " QFP H\n" " DRAM 81237KB(41%) 196608KB 85% 95% H\n" " IRAM 207KB(10%) 2048KB 85% 95% H\n" " CPU Utilization 2.00% 100% 90% 95% H\n\n" "Load Average\n" " Slot Status 1-Min 5-Min 15-Min\n" " RP0 Healthy 1.24 1.20 1.23\n\n" "Memory (kB)\n" " Slot Status Total Used (Pct) Free (Pct) Committed (Pct)\n" " RP0 Healthy 4033104 2909060 (72%) 1124044 (28%) 3749844 (93%)\n\n" "CPU Utilization\n" " Slot CPU User System Nice Idle IRQ SIRQ IOwait\n" " RP0 0 3.51 4.89 0.00 90.10 0.95 0.53 0.00\n" " 1 2.96 4.55 0.00 90.98 1.06 0.42 0.00\n" " 2 21.93 2.01 0.00 75.28 0.67 0.09 0.00\n" " 3 29.17 34.41 0.00 25.93 10.09 0.37 0.00\n\n\n\n\n\n" " 2222233333111111111111111111111111111111 111112222222222\n" " 100\n" " 90\n" " 80\n" " 70\n" " 60\n" " 50\n" " 40\n" " 30\n" " 20\n" " 10\n" " 0....5....1....1....2....2....3....3....4....4....5....5....6\n" " 0 5 0 5 0 5 0 5 0 5 0\n" " CPU% per second (last 60 seconds)\n\n\n\n\n" " 1 1 1 1 1 1 1\n" " 439546515464943339403403334255420343303354853430442395424873\n" " 100\n" " 90\n" " 80\n" " 70\n" " 60\n" " 50\n" " 40\n" " 30\n" " 20\n" " 10 ** **#* * # * * * *** * * * ** * ** *\n" " 0....5....1....1....2....2....3....3....4....4....5....5....6\n" " 0 5 0 5 0 5 0 5 0 5 0\n" " CPU% per minute (last 60 minutes)\n" " * = maximum CPU% # = average CPU%\n" "% Ambiguous command\n" "% Invalid input detected at '^' marker\n" "% Bad Mask /xx for address X.X.X.X\n" "% X.X.X.X overlaps with GigabitEthernet0/1\n" "Command rejected: Conflict between 'nonegotiate' and 'dynamic' status\n" "% Configuration of multiple subinterfaces of the same main interface with the same VID is not permitted\n" "% Configuring IP routing on a LAN subinterface is only allowed if that subinterface is already configured as part of a VLAN\n" "% Inconsistent address and mask\n" "% Invalid next hop address (it's this router)\n\n\n\n") 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