Perl Regex Cheat Sheet

http://perldoc.perl.org/perlre.html



m - Treat string as multiple lines. That is, change "^" and "$" from matching the start or end of the string to matching the start or end of any line anywhere within the string.

s - Treat string as single line. That is, change "." to match any character whatsoever, even a newline, which normally it would not match.
Used together, as /ms, they let the "." match any character whatsoever, while still allowing "^" and "$" to match, respectively, just after and just before newlines within the string.

i - Do case-insensitive pattern matching.

x - Extend your pattern's legibility by permitting whitespace and comments. 

p - Preserve the string matched such that ${^PREMATCH}, ${^MATCH}, and ${^POSTMATCH} are available for use after matching.

g and c - Global matching, and keep the Current position after failed matching. Unlike i, m, s and x, these two flags affect the way the regex is used rather than the regex itself. See Using regular expressions in Perl in perlretut for further explanation of the g and c modifiers.
a, d, l and u



 \        Quote the next metacharacter
    ^        Match the beginning of the line
    .        Match any character (except newline)
    $        Match the end of the line (or before newline at the end)
    |        Alternation
    ()       Grouping
    []       Bracketed Character class



   *           Match 0 or more times
    +           Match 1 or more times
    ?           Match 1 or 0 times
    {n}         Match exactly n times
    {n,}        Match at least n times
    {n,m}       Match at least n but not more than m times



Sequence   Note    Description
  [...]     [1]  Match a character according to the rules of the
                   bracketed character class defined by the "...".
                   Example: [a-z] matches "a" or "b" or "c" ... or "z"
  [[:...:]] [2]  Match a character according to the rules of the POSIX
                   character class "..." within the outer bracketed
                   character class.  Example: [[:upper:]] matches any
                   uppercase character.
  \w        [3]  Match a "word" character (alphanumeric plus "_", plus
                   other connector punctuation chars plus Unicode
                   marks)
  \W        [3]  Match a non-"word" character
  \s        [3]  Match a whitespace character
    \S        [3]  Match a non-whitespace character
  \d        [3]  Match a decimal digit character
  \D        [3]  Match a non-digit character
  \pP       [3]  Match P, named property.  Use \p{Prop} for longer names
  \PP       [3]  Match non-P
  \X        [4]  Match Unicode "eXtended grapheme cluster"
  \C             Match a single C-language char (octet) even if that is
                   part of a larger UTF-8 character.  Thus it breaks up
                   characters into their UTF-8 bytes, so you may end up
                   with malformed pieces of UTF-8.  Unsupported in
                   lookbehind.
  \1        [5]  Backreference to a specific capture group or buffer.
                   '1' may actually be any positive integer.
  \g1       [5]  Backreference to a specific or previous group,
  \g{-1}    [5]  The number may be negative indicating a relative
                   previous group and may optionally be wrapped in
                   curly brackets for safer parsing.
  \g{name}  [5]  Named backreference
  \k<name>  [5]  Named backreference
  \K        [6]  Keep the stuff left of the \K, don't include it in $&
  \N        [7]  Any character but \n (experimental).  Not affected by
                   /s modifier
    \v        [3]  Vertical whitespace
    \V        [3]  Not vertical whitespace
    \h        [3]  Horizontal whitespace
    \H        [3]  Not horizontal whitespace
    \R        [4]  Linebreak


 \b  Match a word boundary
    \B  Match except at a word boundary
    \A  Match only at beginning of string
    \Z  Match only at end of string, or before newline at the end
    \z  Match only at end of string
From JR's : articles
573 words - 4108 chars - 3 min read
created on Apr 10, 2013 at 05:17:01 pm
updated on Sep 24, 2013 at 08:28:50 am - #
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