Characters | Matches |
. | Any single character in the input string. |
^ | A null string at the start of the input string. |
$ | A null string at the end of the input string. |
\x | The character x. A special character that you want to match in the input string can be escaped in this manner, such as \^ or \$. |
[chars] | Any single character from chars. Specifying [a-z] will match any input string containing all lowercase characters. Specifying [0-9a-fA-F] will match any input string containing hexadecimal digits. If a ] character appears as the first characters in chars, it will be treated literally instead of as a terminator. |
[^chars] | Any single character that is not contained in chars. |
(regexp) | Any input string that matches regexp. Parentheses can be used to create complex regular expressions. |
* | A sequence of 0 or more of the preceding atom. |
+ | A sequence of 1 or more of the preceding atom. |
? | Either a null string or the preceding atom. |
regexp1|regexp2 | Anything that matches either regexp1 or regexp2. Note that the | delimiter cannot be preceded by or followed by a blank space. |