Specifications

73
Appendix B
Regular Expressions
You can use regular expressions in many of the Barracuda Web Filter features. Regular Expressions
allow you to flexibly describe text so that a wide range of possibilities can be matched.
The following caveats apply when using regular expressions:
• Be careful when using special characters such as |, *, '.' in your text. For more information, refer
toUsing special characters in expressions on page 74.
• All matches are not case sensitive.
Table B.1 describes the most common regular expressions supported by the Barracuda Web Filter.
Table B.1: Common Regular Expressions
Expression Matches...
Operators
* Zero or more occurrences of the character immediately preceding
+ One or more occurrences of the character immediately preceding
? Zero or one occurrence of the character immediately preceding
| Either of the characters on each side of the pipe
( ) Characters between the parenthesis as a group
Character Classes
. Any character except new line
[ac] Letter 'a' or letter 'c'
[^ac] Anything but letter 'a' or letter 'c'
[a-z] Letters 'a' through 'z'
[a-zA-Z.] Letters 'a' through 'z' or 'A' through 'Z' or a dot
[a-z\-] Letters 'a' through 'z' or a dash
\d Digit, shortcut for [0-9]
\D Non-digit, shortcut for [^0-9]
\a Digit, shortcut for [0-9]
\w Part of word: shortcut for [A-Za-z0-9_]
\W Non-word character: shortcut for [^\w]