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

const regex = /\s(?<filter>PFE_FW_SYSLOG_ETH.*:)\sFW:\s(?<src_interface>[^ ]+)\s.*(?<transport>tcp|udp|icmp)\s(?<src>(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})|(?:[0-9a-fA-F]{1,4}:){7}[0-9a-fA-F]{1,4}$)\s(?<dst>(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})|(?:[0-9a-fA-F]{1,4}:){7}[0-9a-fA-F]{1,4}$)\s(?<src_port>[^ ]+)\s+(?<dest_port>[^ ]+)\s+/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('\\s(?<filter>PFE_FW_SYSLOG_ETH.*:)\\sFW:\\s(?<src_interface>[^ ]+)\\s.*(?<transport>tcp|udp|icmp)\\s(?<src>(\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3})|(?:[0-9a-fA-F]{1,4}:){7}[0-9a-fA-F]{1,4}$)\\s(?<dst>(\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3})|(?:[0-9a-fA-F]{1,4}:){7}[0-9a-fA-F]{1,4}$)\\s(?<src_port>[^ ]+)\\s+(?<dest_port>[^ ]+)\\s+', 'gm') const str = `Aug 2 09:16:37 10.10.10.10 Aug 2 09:16:37 externals-cl fpc1 PFE_FW_SYSLOG_ETH_IP: FW: xe-1/0/0.0 D 0800 34:62:5a:74:8f:c3 -> 64:b2:9a:7e:1b:4a tcp 184.154.189.91 10.1.1.1 41860 465 (1 packets) Aug 2 09:23:13 10.10.10.10 Aug 2 09:23:13 externals-fq fpc0 PFE_FW_SYSLOG_ETH_IP: FW: xe-0/0/0.447 D 03af:0700 a6:e7:f2:2e:13:c7 -> 72:a3:9c:3a:22:00 icmp 185.176.27.46 10.1.1.1 44927 53389 (1 packets) Aug 2 10:00:42 10.10.10.10 Aug 2 10:00:42 externals-fq fpc2 PFE_FW_SYSLOG_ETH_IP: FW: et-2/1/0.716 D 02cc:0800 52:a2:2f:7a:1d:5a -> 84:c9:2b:9e:24:e6 icmp 10.1.1.2 10.1.1.1 3 3 (1 packets)`; // Reset `lastIndex` if this regex is defined globally // regex.lastIndex = 0; let m; while ((m = regex.exec(str)) !== null) { // This is necessary to avoid infinite loops with zero-width matches if (m.index === regex.lastIndex) { regex.lastIndex++; } // 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