| Subexpression | Matches |
|---|
^ | Matches beginning of line. |
$ | Matches end of line. |
. | Matches any single character except newline. Using m option allows it to match newline as well. |
[...] | Matches any single character in brackets. |
[^...] | Matches any single character not in brackets |
\A | Beginning of entire string |
\z | End of entire string |
\Z | End of entire string except allowable final line terminator. |
re* | Matches 0 or more occurrences of preceding expression. |
re+ | Matches 1 or more of the previous thing |
re? | Matches 0 or 1 occurrence of preceding expression. |
re{ n} | Matches exactly n number of occurrences of preceding expression. |
re{ n,} | Matches n or more occurrences of preceding expression. |
re{ n, m} | Matches at least n and at most m occurrences of preceding expression. |
a| b | Matches either a or b. |
(re) | Groups regular expressions and remembers matched text. |
(?: re) | Groups regular expressions without remembering matched text. |
(?> re) | Matches independent pattern without backtracking. |
\w | Matches word characters. |
\W | Matches nonword characters. |
\s | Matches whitespace. Equivalent to [\t\n\r\f]. |
\S | Matches nonwhitespace. |
\d | Matches digits. Equivalent to [0-9]. |
\D | Matches nondigits. |
\A | Matches beginning of string. |
\Z | Matches end of string. If a newline exists, it matches just before newline. |
\z | Matches end of string. |
\G | Matches point where last match finished. |
\n | Back-reference to capture group number "n" |
\b | Matches word boundaries when outside brackets. Matches backspace (0x08) when inside brackets. |
\B | Matches nonword boundaries. |
\n, \t, etc. | Matches newlines, carriage returns, tabs, etc. |
\Q | Escape (quote) all characters up to \E |
\E | Ends quoting begun with \Q |
