Help on Perl Regular Expressions

Reg-expr   | Description
-----------+---------------------------------------------------
.          | Matches any character (except newline)
^          | Matches the start of the string
$          | Matches the end of the string
x?         | Matches 0 or 1 x's, where x is any regular expression
x*         | Matches 0 or more x's
x+         | Matches 1 or more x's
foo|bar    | Matches one of foo or bar
[xyz]      | Matches any character in the set xyz, specify ranges with a -
[^xyz]     | Matches any single character not in the set xyz
\w         | Matches an alpha-numeric character, i.e., [a-zA-Z0-9_]
\s         | Matches a whitespace character
\b         | Matches a word boundary
(x)        | Brackets a regular expression
\metachar  | Matches the metacharacter (takes away its special meaning)

Examples

• The regular expression hello matches the string "hello".
• The regular expression (foo)?bar matches the strings "bar" and "foobar".
• The regular expression ex*tra matches the strings "etra", "extra", "exxtra", "exxxtra" ...

Full details on Perl regular expressions can be found in the Perl manual.