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Regular Expressions 129

Appendix 1

Regular Expressions

The Barracuda Spam Firewall allows you to use regular expressions in many of its features. Regular

Expressions allow you to flexibly describe text so that a wide range of possibilities can be matched.

When using regular expressions:

• Be careful when using special characters such as |, *, '.' in your text. For more information, refer

to Using Special Characters in Expressions on page 130.

• All matches are not case sensitive.

Table 1.1 describes the most common regular expressions supported by the Barracuda Spam Firewall.

Table 1.1: 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]

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Barracuda Networks 4 Guida di Installazione Pagina 129