Hi -

I'd like to know if it's possible to change the time on a Unix box temporarily, do some stuff, and then set it back to the correct time.

I'm testing some code that reads a time (in hours) from a config file, and does something at that time. I want to be able to run regression test scripts at any time.


I envisage doing something like this:
config file:
trigger.hour=7 // do something at 07:00

Invoke regression test script at any time, eg 14:57
- Test script uses date to set the time to 06:59:59
- The code gets invoked when the system time reaches 07:00:00
- Check the right thing happened (test = pass or fail)
- Set the time back to the correct current time (14:57 + ???)

The simplest thing would be if there's a command that goes and finds out what the time is that I can use to reset the clock after my test.
An alternative would be to save the current time, set it to the fake value, run the test, calculate how long the test lasted, and then set the time to (saved_time + elapsed_time) -- but I'm not sure how I would do all that in a shell script.

Any ideas welcome!
Thanks,
Sam