\ | escape (enable or disable meta character meaning) |
| | alternation |
(...) | group |
[...] | character class |
\t | horizontal tab (0x09) |
\v | vertical tab (0x0B) |
\n | newline (0x0A) |
\r | return (0x0D) |
\b | back space (0x08) |
\f | form feed (0x0C) |
\a | bell (0x07) |
\e | escape (0x1B) |
\nnn | octal char (encoded byte value) |
\x{7HHHHHHH} | wide hexadecimal char (character code point value) |
\cx | control char (character code point value) |
\C-x | control char (character code point value) |
\M-x | meta (x|0x80) (character code point value) |
\M-\C-x | meta control char (character code point value) |
(* \b is effective in character class [...] only) |
. | any character (except newline) |
\w | word character (alphanumeric, "_" and multibyte char. See also "A-6. Problems") |
\W | non-word char |
\s | whitespace char (\t, \n, \v, \f, \r, \x20) |
\S | non-whitespace char |
\d | digit char |
\D | non-digit char |
? | 1 or 0 times |
* | 0 or more times |
+ | 1 or more times |
{n,m} | at least n but not more than m times |
{n,} | at least n times |
{,n} | at least 0 but not more than n times ({0,n}) |
{n} | n times |
^ | beginning of the line |
$ | end of the line |
\b | word boundary |
\B | not word boundary |
\A | beginning of string |
\Z | end of string, or before newline at the end |
\z | end of string |
\G | matching start position |
^... | negative class (lowest precedence operator) |
x-y | range from x to y |
[...] | set (character class in character class) |
..&&.. | intersection (low precedence at the next of ^) |
ex. [a-w&&[^c-g]z] ==> ([a-w] AND ([^c-g] OR z)) ==> [abh-w]
* If you want to use '[', '-', ']' as a normal character in a character class, you should escape these characters by '\'.
alnum | alphabet or digit char |
alpha | alphabet |
ascii | code value: [0 - 127] |
blank | \t, \x20 |
cntrl | |
digit | 0-9 |
graph | |
lower | |
punct | |
space | \t, \n, \v, \f, \r, \x20 |
upper | |
xdigit | 0-9, a-f, A-F |
(?#...) | comment |
(?isx-isx) | option on/off
i: ignore case s: single-line (turn off to have dot(.) match newline) x: extended form |
(?isx-isx:subexp) | option on/off for subexp |
(?:subexp) | not captured group |
(subexp) | captured group |
(?=subexp) | look-ahead |
(?!subexp) | negative look-ahead |
(?<=subexp) | look-behind |
(?<!subexp) | negative look-behind |
Subexp of look-behind must be fixed character length. But different character length is allowed in top level alternatives only.
ex. (?<=a|bc) is OK. (?<=aaa(?:b|cd)) is not allowed.
In negative-look-behind, captured group isn't allowed, but shy group(?:) is allowed.
(?>subexp) atomic group don't backtrack in subexp.
(?<name>subexp) define named group (All characters of the name must be a word character.
And first character must not be a digit or upper case)
Not only a name but a number is assigned like a captured group.
Assigning the same name as two or more subexps is allowed.
In this case, a subexp call can not be performed although the back reference is possible.
\n | back reference by group number (n >= 1) |
\k | back reference by group name |
In the back reference by the multiplex definition name, a subexp with a large number is referred to preferentially. (When not matched, a group of the small number is referred to.)
* Back reference by group number is forbidden if named group is defined in the pattern.
You can use these in your replacement strings to transform the case of the replacement results in your searches.
\u | make next char uppercase |
\U | make all following chars uppercase until \u, \L, \l or \E |
\l | make next char lowercase |
\L | make all following chars lowercase until \u, \U, \l or \E |
\E | end case transformation opened by \U or \L |