Regex

regex.md

The following should be escaped if you are trying to match that character

\ ^ . $ | ( ) [ ]
* + ? { } ,

Special Character Definitions

• \ 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
• [] 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

More Special Character Stuff

• \t tab (HT, TAB)
• \n newline (LF, NL)
• \r return (CR)
• \f form feed (FF)
• \a alarm (bell) (BEL)
• \e escape (think troff) (ESC)
• \033 octal char (think of a PDP-11)
• \x1B hex char
• \c[ control char
• \l lowercase next char (think vi)
• \u uppercase next char (think vi)
• \L lowercase till \E (think vi)
• \U uppercase till \E (think vi)
• \E end case modification (think vi)
• \Q quote (disable) pattern metacharacters till \E

Even More Special Characters

• \w Match a "word" character (alphanumeric plus "_")
• \W Match a non-word character
• \s Match a whitespace character
• \S Match a non-whitespace character
• \d Match a digit character
• \D Match a non-digit character
• \b Match a word boundary
• \B Match a non-(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
• \G Match only where previous m//g left off (works only with /g)``*