Cisco Cisco Expressway Maintenance Manual
Regular expressions
Regular expressions can be used in conjunction with a number of Expressway features such as alias
transformations, zone transformations, CPL policy and ENUM. The Expressway uses POSIX format regular
expression syntax. The table below 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 Regular Expression Pocket Reference.
transformations, zone transformations, CPL policy and ENUM. The Expressway uses POSIX format regular
expression syntax. The table below 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 Regular Expression Pocket Reference.
Character Description
Example
.
Matches any single character.
\d
Matches any decimal digit, i.e. 0-9.
*
Matches 0 or more repetitions of the
previous character or expression.
previous character or expression.
.*
matches against any sequence of characters
+
Matches 1 or more repetitions of the
previous character or expression.
previous character or expression.
?
Matches 0 or 1 repetitions of the previous
character or expression.
character or expression.
9?123
matches against 9123 and 123
{n}
Matches n repetitions of the previous
character or expression
character or expression
\d{3}
matches 3 digits
{n,m}
Matches n to m repetitions of the previous
character or expression
character or expression
\d{3,5}
matches 3, 4 or 5 digits
[...]
Matches a set of specified 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.
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 cannot use special characters within
the [] - they will be taken literally.
the [] - they will be taken literally.
[a-z]
matches any alphabetical character
[0-9#*]
matches 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 (*)
plus the hash key (#) and the asterisk key (*)
[^...]
Matches anything except the set of
specified 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.
specified 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 cannot use special characters within
the [] - they will be taken literally.
the [] - they will be taken literally.
[^a-z]
matches any non-alphabetical character
[^0-9#*]
matches anything other than the digits 0-9,
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.
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)
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.
alternate expression.
.*@example.(net|com)
matches against any URI for
the domain example.com or the domain example.net
Cisco Expressway Administrator Guide (X8.1)
Page 262 of 344
Reference material
Regular expressions