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 = /^([0-9-]{4}-[0-9]{2}-[0-9]{2}\s+[0-9]{2}:[0-9]{2}:[0-9]{2})\s+(login|plain) authenticator failed for \(\[?\S+\]?\) \[(\S+)\]:\s+\d+\s+Incorrect authentication data \(set_id=(a|aaaaaa|aamaro|aaron|abc1?2?3?|abel?|access|accounti?n?g?s?|acer?|b?e?s?admi?n?|administracion1|advent|advertising|agency|antigua|apple|asus|avahi|bank|ba?c?kupe?p?p?c?x?e?c?|bbuser|benq|biblioteca|bill|business|bux|carlos|charles|ciclobasico|clamav|clevo|clients?|comenta?|compaq|confirm|confixx|consult|contactu?s?|controller|copier|customer|cvsadmin|cvsroot|cyrus|daemon|data|david|dbadmin|demo|dell|dialer|director|dnscache|doctor|doel|download|drweb|edi|edition|edu|esalguero|estudioazurdia|everest|expe?o?rt|falcon|fax|finance|franciscos|ftp|ftpuser|fujitsu|games|gigabyte|gonzalo.mejia|guest|helpdesk|holding|home|hp|ibm|ice|iloveyou|imac|info|install|internet|iphone|jabber|jc|jefaturaventas|jeremy|jgarcia|job|john|jorge|jude|kattytoc|kim|laboratorio|ldap|lenovo|lsarmiento|lschoenstedt|manager|margarita|marketing|monkey|mpalma|municipal|multimedia|news|newsletter|nobody|office|pastores|pos|postmaster|princess|printer|PXF.info|reception|sales|samsung|scann?e?r?|security|shadow|shop|spam|student|sunshine|support|sys|tech|temp|test1?u?s?e?r?|toshiba|training|user1?s?|wzarate|xerox)\)/; // Alternative syntax using RegExp constructor // const regex = new RegExp('^([0-9-]{4}-[0-9]{2}-[0-9]{2}\\s+[0-9]{2}:[0-9]{2}:[0-9]{2})\\s+(login|plain) authenticator failed for \\(\\[?\\S+\\]?\\) \\[(\\S+)\\]:\\s+\\d+\\s+Incorrect authentication data \\(set_id=(a|aaaaaa|aamaro|aaron|abc1?2?3?|abel?|access|accounti?n?g?s?|acer?|b?e?s?admi?n?|administracion1|advent|advertising|agency|antigua|apple|asus|avahi|bank|ba?c?kupe?p?p?c?x?e?c?|bbuser|benq|biblioteca|bill|business|bux|carlos|charles|ciclobasico|clamav|clevo|clients?|comenta?|compaq|confirm|confixx|consult|contactu?s?|controller|copier|customer|cvsadmin|cvsroot|cyrus|daemon|data|david|dbadmin|demo|dell|dialer|director|dnscache|doctor|doel|download|drweb|edi|edition|edu|esalguero|estudioazurdia|everest|expe?o?rt|falcon|fax|finance|franciscos|ftp|ftpuser|fujitsu|games|gigabyte|gonzalo.mejia|guest|helpdesk|holding|home|hp|ibm|ice|iloveyou|imac|info|install|internet|iphone|jabber|jc|jefaturaventas|jeremy|jgarcia|job|john|jorge|jude|kattytoc|kim|laboratorio|ldap|lenovo|lsarmiento|lschoenstedt|manager|margarita|marketing|monkey|mpalma|municipal|multimedia|news|newsletter|nobody|office|pastores|pos|postmaster|princess|printer|PXF.info|reception|sales|samsung|scann?e?r?|security|shadow|shop|spam|student|sunshine|support|sys|tech|temp|test1?u?s?e?r?|toshiba|training|user1?s?|wzarate|xerox)\\)', '') const str = `2019-05-02 09:56:31 plain authenticator failed for ([46.232.112.23]) [46.232.112.23]: 535 Incorrect authentication data (set_id=tanya) 2019-05-02 09:56:36 plain authenticator failed for ([185.222.209.56]) [185.222.209.56]: 535 Incorrect authentication data (set_id=erich) 2019-05-02 09:57:12 login authenticator failed for (User) [185.36.81.180]: 535 Incorrect authentication data (set_id=admin1) 2019-05-02 09:57:16 plain authenticator failed for ([177.21.129.124]) [177.21.129.124]: 535 Incorrect authentication data (set_id=kyle@canvas.co.za) 2019-05-02 09:57:18 login authenticator failed for (User) [185.36.81.173]: 535 Incorrect authentication data (set_id=demo1) `; // 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