I've seen in the manual that there is ZoneMinder-1.23.3/scripts/zmtrigger.pl:
â€˜showtextâ€™ is up to 32 characters of text that can be displayed in the timestamp that is added to images. The â€˜showâ€™ action is designed to update this text without affecting alarms but the text is updated, if present, for any of the actions. This is designed to allow external input to appear on the images captured, for instance temperature or personnel identity etc.
But I can't find an instruction on how to use zmtrigger...?