+
+\-\-filter 'expression'
+ Set a filter on a newly enabled event.
+ Filter expression on event fields, event recording
+ depends on evaluation. Only specify on first activation
+ of a given event within a session. Filter only allowed
+ when enabling events within a session before tracing is
+ started. If the filter fails to link with the event
+ within the traced domain, the event will be discarded.
+ Currently, filter is only implemented for the user-space
+ tracer.
+ Expression examples:
+
+ 'intfield > 500 && intfield < 503'
+ '(stringfield == "test" || intfield != 10) && intfield > 33'
+ 'doublefield > 1.1 && intfield < 5.3'
+
+ Wildcards are allowed at the end of strings:
+ 'seqfield1 == "te*"'
+ In string literals, the escape character is a '\\'.
+ Use '\\*' for the '*' character, and '\\\\' for the
+ '\\' character.
+