expression expression

Regular expression pattern element. Optional in <rule> elements.

Attributes section-2d438c889ae84b6da7e0ed84b5d021a0


Data section-e2601008d71243109af1a8c55b58416d

Regular-expression pattern string.

Description section-759bfb738ddb45dba1f0807aba8c1113

The <expression> element can be empty or contain a simple search string or a regular-expression pattern. The pattern is applied to the entire request string.

A match always occurs when <expression> is empty or not specified; this is equivalent to specifying <expression>.*</expression>.

The implementation is based on the Java package java.util.regex, which provides regular expression syntax similar to Perl’s.

Notes section-10b472a902674893b49ca49a7052c366

The expression string must not contain literal < and & characters. These reserved characters can be encoded with & and <, respectively, or the entire string can be enclosed in an XML CDATA section:


All characters between the <expression> and </expression> tags are passed to the regular expression parser, including characters outside the optional CDATA section. Care should be taken to avoid extra whitespace.

See also section-ca98548917d945f4b71f18208f0e6840