[abc]
|
A single character: a, b or c |
[^abc]
|
Any single character but a, b, or c |
[a-z]
|
Any single character in the range a-z |
[a-zA-Z]
|
Any single character in the range a-z or A-Z |
^
|
Start of line |
$
|
End of line |
\A
|
Start of string |
\z
|
End of string |
.
|
Any single character |
\s
|
Any whitespace character |
\S
|
Any non-whitespace character |
\d
|
Any digit |
\D
|
Any non-digit |
\w
|
Any word character (letter, number, underscore) |
\W
|
Any non-word character |
\b
|
Any word boundary character |
(...)
|
Capture everything enclosed |
(a|b)
|
a or b |
a?
|
Zero or one of a |
a*
|
Zero or more of a |
a+
|
One or more of a |
a{3}
|
Exactly 3 of a |
a{3,}
|
3 or more of a |
a{3,6}
|
Between 3 and 6 of a |
options: i case insensitive; m make dot match newlines; x ignore whitespace in regex; o perform #{...} substitutions only once