expression expression

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

Attributes section-fd0574eee1f9423cbb2ed709c0906800


Data section-4cd740c511a1432da0955e9acfbcf96f

Regular-expression pattern string.

Description section-3245c8a531bb455d8398449f6ea63b37

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 a regular-expression syntax similar to Perl’s.

Note section-6b41a900b0ce4a9590e5861e3c81599c

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-15a9fea18e644b8e9c498f5fd88e2eaa