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

/
/
gxm

Test String

Code Generator

Language

Generated Code

re = /\[\ (RUNNING|STOPPED)\ \] (.+?) (?:\[Pid:\ (\d+)\]|$)/xm str = ' I want to extract the words between the two bracket "blocks" and also the word in first brackets (RUNNING or STOPPED). Example (extract the bolded part): [ RUNNING ] My First Application [Pid: 4194] [ RUNNING ] Second app (some data) [Pid: 5248] [ STOPPED ] Logger App So, as you can see, the [Pid: X] part is optional. I can write the regex as follows: \\[\\s+(RUNNING|STOPPED)\\s+\\]\\s+([^\\[]+).* and it will work. But this would fail if App name would contain the \'[\' character. I tried the following, but it won\'t work: \\[\\s+(RUNNING|STOPPED)\\s+\\]\\s+(?!\\[Pid)+.* My idea was to match any words/characters that are not starting with "[Pid", but I guess this would match any words that are not followed by "[Pid". Is there any way to do exactly that: Match any word that is not "[Pid", i.e. match the part until first appearing of "[Pid" substring? ' # Print the match result str.scan(re) do |match| puts match.to_s end

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 Ruby, please visit: http://ruby-doc.org/core-2.2.0/Regexp.html