Forums Scripts & Popups Best way to Calculate time passed?

Basically i wanna have a script write to a file when an event happends, and then when some other event happends i want it to check that file and see if a required amount of time has passed.

So its most likely very simple i just dont know shyt about time elapsing and junk. I just want it to say..
Mark time now..
Then see if 3 seconds has passed. (or whatever amount of seconds i choose).

Please include an example, cuz like with the help file and $ctime, $asctime, ect.., im lost lol. Ty

//set %testing.time $ctime
//echo ! $duration($calc($ctime - %testing.time))