|
Pattern Description
/pattern/options Pattern pattern in slashes, followed by optional options, one or more of: i for case-insensitive; o for substitute once; x for ignore whitespace, allow comments; m for match multiple lines and newlines as normal characters.
%r!pattern! General delimited string for a regular expression, where ! can be an arbitrary character.
^ Matches beginning of line.
$ Matches end of line.
. Matches any character.
\1...\9 Matches nth grouped subexpression.
\10 Matches nth grouped subexpression if already matched; otherwise, refers to octal representation of a character code.
\n, \r, \t, etc. Matches character in backslash notation.
\w Matches word character; same as [0-9A-Za-z_].
\W Matches nonword character; same as [^0-9A-Za-z_].
\s Matches whitespace character; same as [\t\n\r\f].
\S Matches nonwhitespace character; same as [^\t\n\r\f].
\d Matches digit; same as [0-9].
\D Matches nondigit; same as [^0-9].
\A Matches beginning of a string.
\Z Matches end of a string, or before newline at the end.
\z Matches end of a string.
\b Matches word boundary outside [] or backspace (0x08) inside [].
\B Matches nonword boundary.
\G Matches point where last match finished.
[..] Matches any single character in brackets, such as [ch].
[^..] Matches any single character not in brackets.
* Matches zero or more of previous regular expressions.
*? Matches zero or more of previous regular expressions (nongreedy).
+ Matches one or more of previous regular expressions.
+? Matches one or more of previous regular expressions (nongreedy).
{m} Matches exactly m number of previous regular expressions.
{m,} Matches at least m number of previous regular expressions.
{m,n} Matches at least m but at most n number of previous regular expressions.
{m,n}? Matches at least m but at most n number of previous regular expressions (nongreedy).
? Matches zero or one of previous regular expression.
| Alternation, such as color|colour.
( ) Groups regular expressions or subexpression, such as col(o|ou)r.
(?#..) Comment.
(?:..) Groups without back-references (without remembering matched text).
(?=..) Specifies position with pattern.
(?!..) Specifies position with pattern negation.
(?>..) Matches independent pattern without backtracking.
(?imx) Toggles i, m, or x options on.
(?-imx) Toggles i, m, or x options off.
(?imx:..) Toggles i, m, or x options on within parentheses.
(?-imx:..) Toggles i, m, or x options off within parentheses.
(?ix-ix: ) Turns on (or off) i and x options within this noncapturing group.
[:alnum:] class for alphanumeric.
[:alpha:] class for uppercase and lowercase letters.
[:blank:] class for blank and tab.
[:cntrl:] class for Control characters.
[:digit:] class for digits.
[:graph:] class for printable characters (but not space).
[:lower:] class for lowercase letter.
[:print:] class for printable characters (space included).
[:punct:] class for printable characters (but not space and alphanumeric).
[:space:] class for whitespace.
[:upper:] class for uppercase letters.
[:xdigit:] class for hex digits: A-F, a-f, and 0-9.
|