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