Quick reference

Special characters definitions

\   Quotes the next meta character
^   Match the beginning of a line
.   Match any character (except newline character)
$   Match the end of a line
|   Alternation
()  Group
[]  Character class

*      Match 0 or more times
+      Match 1 or more times
?      Match 0 or 1 times
{n}    Match exactly n times
{n,}   Match at least n times
{n,m}  Match at least n but no more than m times

Character classes

[abc]          a, b, or c (simple class)
[^abc]         Any character except a, b, or c (negation)
[a-zA-Z]       a through z, or A through Z, inclusive (range)
[a-d[m-p]]     a through d, or m through p: [a-dm-p] (union)
[a-z&&[def]]   d, e, or f (intersection)
[a-z&&[^bc]]   a through z, except b and c: [ad-z] (subtraction)
[a-z&&[^m-p]]  a through z, but excluding m through p: [a-lq-z] (subtraction)

Pre-defined character classes

.    Any character (except newline character)
\d   A digit character: [0-9]
\D   A non-digit character: [^0-9]
\s   A whitespace character: [ \t\n\x0B\f\r]
\S   A non-whitespace character: [^\s]
\w   A word character: [a-zA-Z_0-9]
\W   A non-word character: [^\w]