Hi, I wrote:

def register_exit_func(func, *args, **kw): import sys previous_func = sys.exit_func

this should have been 'sys.exitfunc'. I've also misssed to note, that I placed the following line into the module init code: import sys; def _nop(): pass; sys.exitfunc = _nop Otherwise I had to use getattr(sys, 'exitfunc', None) as David suggested. Next time I should actually cut'n'paste working code instead typing from blurred memory. :-( Another point I forgot, was that you usually want to install signal handlers on unices, that handle the signal.SIGTERM, signal.SIGHUP and signal.SIGINT signals and invoke exit function to do some final cleanup. Regards, Peter