3 min Perl Regex Cheat Sheet http://perldoc.perl.org/perlre.html http://perldoc.perl.org/perlreref.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 574 words - 4147 chars - 3 min read created on Apr 10, 2013 at 06:17:01 pm updated on Jun 19, 2017 at 12:39:37 pm import date 2013-08-12 21:49:43 - # source - versions