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 = /IN=(?P<source_interface>(\S+|\s?)) OUT=(?P<forward_interface>(\S+|\s?)) MAC=(?P<source_mac>(\S+|\s?)) SRC=(?P<source_ip>(?:([0-9]{1,3}\.){3}[0-9]{1,3})) DST=(?P<destination_ip>(?:([0-9]{1,3}\.){3}[0-9]{1,3})) LEN=(?P<pkt_len>\d+) TOS=(?P<pkt_tos>[\dx\d]+) PREC=(?P<pkt_prec>[\dx\d]+) TTL=(?P<pkt_ttl>\d+) ID=(?P<pkt_id>\d+)\s?(?P<pk_frg>[A-Z\s].?)\s?PROTO=(?P<pkt_protocol>[\w\d]+) SPT=(?P<source_port>\d+) DPT=(?P<dest_port>\d+) (LEN=(?P<pkt_length>\d+))?(WINDOW=(?P<pkt_window>\d+) RES=(?P<pkt_res>[\dx\d]+)? (?P<pkt_type>(\S+))?\s?(URGP=(?P<pkt_urgency>\d))?)?/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('IN=(?P<source_interface>(\\S+|\\s?)) OUT=(?P<forward_interface>(\\S+|\\s?)) MAC=(?P<source_mac>(\\S+|\\s?)) SRC=(?P<source_ip>(?:([0-9]{1,3}\\.){3}[0-9]{1,3})) DST=(?P<destination_ip>(?:([0-9]{1,3}\\.){3}[0-9]{1,3})) LEN=(?P<pkt_len>\\d+) TOS=(?P<pkt_tos>[\\dx\\d]+) PREC=(?P<pkt_prec>[\\dx\\d]+) TTL=(?P<pkt_ttl>\\d+) ID=(?P<pkt_id>\\d+)\\s?(?P<pk_frg>[A-Z\\s].?)\\s?PROTO=(?P<pkt_protocol>[\\w\\d]+) SPT=(?P<source_port>\\d+) DPT=(?P<dest_port>\\d+) (LEN=(?P<pkt_length>\\d+))?(WINDOW=(?P<pkt_window>\\d+) RES=(?P<pkt_res>[\\dx\\d]+)? (?P<pkt_type>(\\S+))?\\s?(URGP=(?P<pkt_urgency>\\d))?)?', 'gm') const str = `IN=pppoe0 OUT= MAC= SRC=45.134.26.235 DST=51.148.135.105 LEN=40 TOS=0x00 PREC=0x00 TTL=244 ID=21599 PROTO=TCP SPT=41497 DPT=33241 WINDOW=1024 RES=0x00 SYN URGP=0 IN=eth1 OUT=eth1.20 MAC=fc:ec:da:47:47:e6:b4:2e:99:19:8e:79:08:00 SRC=10.231.1.21 DST=10.231.20.5 LEN=60 TOS=0x00 PREC=0x00 TTL=63 ID=22819 DF PROTO=TCP SPT=58474 DPT=8123 WINDOW=64240 RES=0x00 SYN URGP=0 IN=eth1.40 OUT=eth1 MAC=fc:ec:da:47:47:e6:ea:5e:e5:92:bd:3d:08:00:45:00:00:46 SRC=10.231.40.108 DST=10.231.1.22 LEN=70 TOS=0x00 PREC=0x00 TTL=63 ID=58349 DF PROTO=UDP SPT=58673 DPT=53 LEN=50 IN=pppoe0 OUT= MAC= SRC=37.120.166.236 DST=51.148.135.105 LEN=60 TOS=0x00 PREC=0x00 TTL=52 ID=27591 DF PROTO=TCP SPT=35990 DPT=18080 WINDOW=29200 RES=0x00 SYN URGP=0`; // 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