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

[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)

.	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]