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

/
/

Test String

Code Generator

Language

Generated Code

const regex = /.+HappyMK\s?(?<action>\S+)\s(?<chain>\w+):\sin:(?<int_in>\S+)\sout:(?<int_out>\S+), src-mac\s(?<src_mac>\S+),\sproto\s(?<prot>\w+)(\s(?<flags>\S+),|,)\s(?<src_ip>\b(?:\d{1,3}\.){3}\d{1,3}\b):(?<src_port>\d+)->(?<dest_ip>\b(?:\d{1,3}\.){3}\d{1,3}\b):(?<dest_port>\d+),(\s(?<NAT>\w+)\s\((?<src_nat_localip>\b(?:\d{1,3}\.){3}\d{1,3}\b):(?<src_nat_local_port>\d+)->(?<src_nat_public_ip>\b(?:\d{1,3}\.){3}\d{1,3}\b):(?<src_nat_public_port>\d+)\)->(?<dest_nat_ip>\b(?:\d{1,3}\.){3}\d{1,3}\b):(?<dest_nat_port>\d+),)?(\sprio\s(?<prio>\d+->\d+),)?\slen\s(?<len>\d+)/; // Alternative syntax using RegExp constructor // const regex = new RegExp('.+HappyMK\\s?(?<action>\\S+)\\s(?<chain>\\w+):\\sin:(?<int_in>\\S+)\\sout:(?<int_out>\\S+), src-mac\\s(?<src_mac>\\S+),\\sproto\\s(?<prot>\\w+)(\\s(?<flags>\\S+),|,)\\s(?<src_ip>\\b(?:\\d{1,3}\\.){3}\\d{1,3}\\b):(?<src_port>\\d+)->(?<dest_ip>\\b(?:\\d{1,3}\\.){3}\\d{1,3}\\b):(?<dest_port>\\d+),(\\s(?<NAT>\\w+)\\s\\((?<src_nat_localip>\\b(?:\\d{1,3}\\.){3}\\d{1,3}\\b):(?<src_nat_local_port>\\d+)->(?<src_nat_public_ip>\\b(?:\\d{1,3}\\.){3}\\d{1,3}\\b):(?<src_nat_public_port>\\d+)\\)->(?<dest_nat_ip>\\b(?:\\d{1,3}\\.){3}\\d{1,3}\\b):(?<dest_nat_port>\\d+),)?(\\sprio\\s(?<prio>\\d+->\\d+),)?\\slen\\s(?<len>\\d+)', '') const str = `May 30 11:56:03 10.10.0.1 May 30 11:56:04 HappyMK Accept forward: in:bridge-vlan11 out:ether1-gateway, src-mac 60:c5:47:09:bd:c8, proto TCP (SYN), 10.11.0.251:58615->17.134.126.209:443, prio 1->0, len 64 May 30 11:55:29 10.10.0.1 May 30 11:55:29 HappyMK Accept forward: in:vlan10 out:ether1-gateway, src-mac 00:60:6e:a5:61:c1, proto UDP, 10.10.0.14:62164->157.56.106.184:3544, NAT (10.10.0.14:62164->89.141.65.84:62164)->157.56.106.184:3544, len 84 May 30 11:56:25 10.10.0.1 May 30 11:56:26 HappyMK Accept forward: in:vlan10 out:ether1-gateway, src-mac 00:60:6e:a5:61:c1, proto UDP, 10.10.0.14:62164->157.56.106.189:3544, len 84 `; // Reset `lastIndex` if this regex is defined globally // regex.lastIndex = 0; let m; if ((m = regex.exec(str)) !== null) { // The result can be accessed through the `m`-variable. m.forEach((match, groupIndex) => { console.log(`Found match, group ${groupIndex}: ${match}`); }); }

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 JavaScript, please visit: https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions