*

The wildcard (*) is used to match all characters in the string. The expression *.html will match all files with a .html file extension, such as index.html, out.html, and so forth.

?

The question mark (?) will match a single character of the string. The expression lmn?p will match the sub-string lmnop, lmnep, and so forth.

\

Used to quote a meta-character (like ’*’)

\\

Matches a single ’\’ character

(A)

Groups subexpressions (affects order of pattern evaluation)

[abc]

Simple character class (any character within brackets matches the target character)

[a-zA-Z]

Character class with ranges (any character range within the brackets matches the target character)

[^abc]

Negated character class

.

Matches any character other than newline

^

Matches only at the beginning of a line

$

Matches only at the end of a line

A*

Matches A 0 or more times (greedy)

A+

Matches A 1 or more times (greedy)

A?

Matches A 1 or 0 times (greedy)

A{n}

Matches A exactly n times (greedy)

A{n,}

Matches A at least n times (greedy)

A{n,m}

Matches A at least n but not more than m times (greedy)

A*?

Matches A 0 or more times (reluctant)

A+?

Matches A 1 or more times (reluctant)

A??

Matches A 0 or 1 times (reluctant)

AB

Matches A followed by B

A|B

Matches either A or B

\1

Backreference to 1st parenthesized subexpression

\n

Backreference to nth parenthesized subexpression