|

Indicates that a match can be one of the two terms on either side of the pipe.

^

Used at the beginning of an expression, denotes where a match should begin.

$

Used at the end of an expression, denotes that a term must be matched exactly up to the point of the $ character.

[ ]

Specifies a range of letters or digits to match. To separate the start and end of a range, use a hyphen ( - ).

( )

Specifies a group of terms to match. Stored as numbered variables. Use for back references as \1 \2 .... \9.

*

0 or more terms.

+

One or more terms.

.

Any character except for a space (" ").

\

A backslash escapes special characters to suppress their special meaning. For example, \. matches . (period symbol).

\n

Back reference. Matches the nth group.

&

Back reference. Matches the entire match.

replace pattern myrouter with router1

Match: myrouter

Result: router1

replace pattern " 192\.168\.(.*)/24" with " 10.2.\1/28"

Match: 192.168.3.4/24

Result: 10.2.3.4/28

replace pattern " 1.\1" with " abc&def"

Match: 1.1

Result: abc1.1def

replace pattern 1.1 with " abc\&def"

Match: 1#1

Result: abc&def