What do you mean by "trigger itself to run"? For a program to trigger anything, it must run. It can't do anything, unless it runs. And since you specifically disallow another program to do this triggering, it isn't at all clear to me what you mean.

For a program that sleeps, there are two, and only two, ways of how it can be awakened: it reaches the end of the interval it went asleep for, or it caught a signal (and with some implementation of sleep, this is the same thing).

Perhaps you could explain what your ultimate goal is?

Abigail