In trigger function strlen() the strlen(#num) does not work according to manual https://www.zabbix.com/documentation/current/manual/appendix/triggers/functions but seems to be ignored instead.

To reproduce:

• create empty file /var/tmp/tstfile on zabbix server
• create new Item on Zabbix Server 'test' with

• • Type Zabbix Agent
  • Key vfs.file.contents[/var/tmp/tstfile]
  • Type of information Text
• create Trigger 'strln-test-trigger'
  • Expression:

    {Zabbix server:vfs.file.contents[/var/tmp/tstfile].strlen(#4)}>0 

  Observation: when adding some text to /var/tmp/tstfile, the trigger is active immediately after the next check, instead of  the 4th check.