testing if another instance of a script is already running

[Strato]

Hi folks,

I want to write some kind of test to check at startup if another 
instance of my script is already running.

I don't want to handle writing of a PID file because it is too 
Unix/Linux specific way to do this, and I need to keep the code to be 
cross-platform.

I think the better way to achieve this is to use some process control, 
but I'm a neebie and I don't see how to do this in a safe and clean way.

Any idea ?

Best regards,
Strato