Regular expressions can be used in conjunction
with a number of VCS features such as alias
transformations, zone transformations, CPL
policy and ENUM. The VCS uses POSIX format
regular expression syntax.
The table opposite provides a list of
commonly used special characters in
regular expression syntax. This is only a
subset of the full range of expressions
available. For a detailed description of
regular expression syntax see the publication

Mastering Regular Expressions [9]

For an example of regular expression
usage, see the

CPL examples

section.

Character

Description

Example

Matches any single character.

Matches 0 or more repetitions of the previous match.

.* will match against any sequence of characters.

Matches 1 or more repetitions of the previous match.

Escapes a regular expression special character.

Matches any decimal digit, i.e. 0-9.

[...]

Matches a set of characters. Each character in the set
can be specified individually, or a range can be specified
by giving the first character in the range followed by the

- character and then the last character in the range.
You can not use special characters within the

[] - they

will be taken literally.

[a-z] will match against any lower case alphabetical character.
[a-zA-Z] will match against any alphabetical character.
[0-9#*] will match against any single E.164 character - the E.164 character

set is made up of the digits

0-9 plus the hash key (#) and the asterisk key

(

*).

(...)

Groups a set of matching characters together. Groups
can then be referenced in order using the characters

\1, \2, etc. as part of a replace string.

A regular expression can be constructed to transform a URI containing a
user’s full name to a URI based on their initials.
The regular expression

(.).* _ (.).*(@example.com) would match against

the user

john _ smith@example.com and with a replace string of \1\2\3

would transform it to

js@example.com.

Matches against one expression or an alternate
expression.

.*@example.(net|com) will match against any URI for the domain

example.com or the domain example.net.

Signifies the start of a line.
When used immediately after an opening brace, negates
the character set inside the brace.

[^abc] matches any single character that is NOT one of a, b or c.

Signifies the end of a line.

^\d\d\d$ will match any string that is exactly 3 digits long.

(?!...)

Negative lookahead. Defines a subexpression that must
not be present in order for there to be a match.

(?!.*@example.com$).* will match any string that does not end with @

example.com.

Overview

Common regular expressions