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

# coding=utf8 # the above tag defines encoding for this document and is for Python 2.x compatibility import re regex = r"^(?<exe>npm)?\ ?(?<run>(?<=\k<exe> )run(?:-script)?)?\ ?(?<command>(?<=\k<run> )[a-z]+(?:[-|:|.|_][a-z]+)?|(?<!\k<run> )[a-z]+(?:[-][a-z]+)?)?\ ?(?<pkgdetails>[a-z0-9\>\=\:\+\#\^\.\@\/][a-z0-9\>\=\:\+\#\^\~\.\@\/\-]+)?\ ?(?<options>(?:\ [-]{1,2}[a-zA-Z]+(?:[-][a-z]+)*)*)?$" test_str = ("npm install cordova-browser@~5.0.1 --production --save\n\n" "npm install --no-package-lock\n" "npm -v\n\n" "npm version major\n" "npm version minor\n" "npm version patch\n\n" "npm run build\n" "npm run build:spypkg\n" "npm run build-spypkg\n" "npm run build.spypkg\n" "npm run build_spypkg\n" "npm run-script build:spypkg\n" "npm run-script build-spypkg\n" "npm run-script build.spypkg\n" "npm run-script build_spypkg\n\n" "i sots --D\n" "i sots --production\n" "i sots --production --no-save\n" "install sots --production --no-save\n" "npm install sots --production --no-save\n\n" "npm install ./package.tgz\n" "npm install https://github.com/indexzero/forever/tarball/v0.5.6\n" "npm install sax\n" "npm install sax -P\n" "npm install sax -D\n" "npm install sax -O\n\n" "i\n\n" "npm i\n" "i sax\n" "i sax -D\n" "install\n" "install sax -P\n" "install sax -D\n" "install sax -O\n" "npm install githubname/reponame\n" "npm install @myorg/privatepackage\n" "npm install node-tap --save-dev\n" "npm install dtrace-provider --save-optional\n" "npm install readable-stream --save-exact\n" "npm install ansi-regex --save-bundle\n" "npm install sax@latest\n" "npm install @myorg/mypackage@latest\n" "npm install sax@0.1.1\n" "npm install @myorg/privatepackage@1.5.0\n" "npm install sax@\">=0.1.0 <0.2.0\"\n" "npm install @myorg/privatepackage@\">=0.1.0 <0.2.0\"\n" "npm install git+ssh://git@github.com:npm/cli.git#v1.0.27\n" "npm install git+ssh://git@github.com:npm/cli#semver:^5.0\n" "npm install git+https://isaacs@github.com/npm/cli.git\n" "npm install git://github.com/npm/cli.git#v1.0.27\n" "npm install mygithubuser/myproject\n" "npm install github:mygithubuser/myproject\n" "npm install gist:101a11beef\n" "npm install bitbucket:mybitbucketuser/myproject\n" "npm install gitlab:mygitlabuser/myproject\n" "npm install gitlab:myusr/myproj#semver:^5.0\n" "npm install sax@\">=0.1.0 <0.2.0\" bench supervisor\n" "npm install sax --force") matches = re.finditer(regex, test_str, re.MULTILINE) for matchNum, match in enumerate(matches, start=1): print ("Match {matchNum} was found at {start}-{end}: {match}".format(matchNum = matchNum, start = match.start(), end = match.end(), match = match.group())) for groupNum in range(0, len(match.groups())): groupNum = groupNum + 1 print ("Group {groupNum} found at {start}-{end}: {group}".format(groupNum = groupNum, start = match.start(groupNum), end = match.end(groupNum), group = match.group(groupNum))) # Note: for Python 2.7 compatibility, use ur"" to prefix the regex and u"" to prefix the test string and substitution.

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