get the en of a program running in background

[Damjan]

> It works when a click on a button launches a program P.
> Now, I want that a click on another button launches another program P'
> 
> In this case there is only one signal for two events : the end of P and
> the end of P'.
> How can distinct the two cases.

Remember the PIDs of the forked procesess and in your signal handler use
os.wait() to see which one has died. 
BTW os.wait() can work in non-blocking mode .


-- 
damjan