Rules Expression Editor
- Last Updated: April 2, 2026
- 1 minute read
Passive monitors and other monitors that provide pattern checking enable you to apply simple regular expression syntax. You can use a rule expression to test a string or a page of text for pattern matching. You can check for word frequency, HTTP error pages, literal strings, and much more.
-
Regular Expression
Select from a list of patterns.- Match case. Enable case-sensitive match.
- Invert result. (Inverse match) Evaluate to true when not a match.
- Comparison text. Provide a target string for testing purposes. Please note, entries in this field are temporary and will not be saved after closing the Rules Expression Editor dialog.
- Test. Test if your expression pattern matches the target.
After creating and testing the expression, click OK to insert the string into the Match on box.
Note: If you have multiple message "match on" expressions, they are linked
by "OR" logic - not "AND" logic. Example: If you have two expressions, one set to "AB"
and the other to "BA", it will match against a trap containing any of the following:
"AB" or "BA" or "ABBA".