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
Processing...

Test String

Code Generator

Language

Generated Code

import re regex = re.compile(r"^\w+(?=\s+OBJECT-TYPE)", flags=re.IGNORECASE | re.MULTILINE) test_str = ("STEELHEAD-MIB DEFINITIONS ::= BEGIN\n\n" "IMPORTS\n" " OBJECT-TYPE, MODULE-IDENTITY, NOTIFICATION-TYPE, Unsigned32,\n" " TimeTicks, IpAddress, Counter32, Counter64 FROM SNMPv2-SMI\n" " DateAndTime FROM SNMPv2-TC\n" " products FROM RBT-MIB;\n\n" "steelhead MODULE-IDENTITY\n" " LAST-UPDATED \"201401070000Z\"\n" " ORGANIZATION \"Riverbed Technology, Inc.\"\n" " CONTACT-INFO\n" " \" Riverbed Technical Support\n" " support@riverbed.com\"\n" " DESCRIPTION \"Steelhead MIB\"\n" " REVISION \"201401070000Z\"\n" " DESCRIPTION \"Connection forwarding cluster incompatible trap\"\n" " REVISION \"201301250000Z\"\n" " DESCRIPTION \"Corrections in descriptions of some traps\"\n" " REVISION \"201210170000Z\"\n" " DESCRIPTION \"Added trap for CF Peer IPv6 incompatible alarm\"\n" " REVISION \"201202030000Z\"\n" " DESCRIPTION \"Updated for 7.0.1\"\n" " ::= { products 1 }\n\n" "system OBJECT IDENTIFIER\n" " ::= { steelhead 1 }\n\n" "status OBJECT IDENTIFIER\n" " ::= { steelhead 2 }\n\n" "config OBJECT IDENTIFIER\n" " ::= { steelhead 3 }\n\n" "alarms OBJECT IDENTIFIER\n" " ::= { steelhead 4 }\n\n" "statistics OBJECT IDENTIFIER\n" " ::= { steelhead 5 }\n\n" "--\n" "--\n" "-- SYSTEM\n" "--\n" "--\n\n" "model OBJECT-TYPE\n" " SYNTAX OCTET STRING\n" " MAX-ACCESS read-only\n" " STATUS current\n" " DESCRIPTION\n" " \"Appliance model\"\n" " ::= { system 1 }\n\n" "serialNumber OBJECT-TYPE\n" " SYNTAX OCTET STRING\n" " MAX-ACCESS read-only\n" " STATUS current\n" " DESCRIPTION\n" " \"Appliance serial number\"\n" " ::= { system 2 }\n\n" "systemVersion OBJECT-TYPE\n" " SYNTAX OCTET STRING\n" " MAX-ACCESS read-only\n" " STATUS current\n" " DESCRIPTION\n" " \"System software version string\"\n" " ::= { system 3 }\n\n\n\n" "--\n" "--\n" "-- STATUS\n" "--\n" "--\n\n" "systemClock OBJECT-TYPE\n" " SYNTAX DateAndTime\n" " MAX-ACCESS read-only\n" " STATUS current\n" " DESCRIPTION\n" " \"System clock time\"\n" " ::= { status 1 }\n\n" "health OBJECT-TYPE\n" " SYNTAX OCTET STRING\n" " MAX-ACCESS read-only\n" " STATUS current\n" " DESCRIPTION\n" " \"Current health of the system. The value is one amongst\n" " Healthy, Admission Control, Degraded, Critical\"\n" " ::= { status 2 }\n\n" "serviceStatus OBJECT-TYPE\n" " SYNTAX OCTET STRING\n" " MAX-ACCESS read-only\n" " STATUS current\n" " DESCRIPTION\n" " \"Current status of the optimization service\"\n" " ::= { status 3 }") matches = regex.finditer(test_str) for match_num, match in enumerate(matches, start=1): print(f"Match {match_num} was found at {match.start()}-{match.end()}: {match.group()}") for group_num, group in enumerate(match.groups(), start=1): print(f"Group {group_num} found at {match.start(group_num)}-{match.end(group_num)}: {group}")

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