Writing a program that cannot be killed except by reboot

[Keith Bloom]

mcgough at wrdis01.af.mil (Jeffrey B. McGough) writes:

>Is there anyway to block ALL signals to a program so that it
>may not be killed by kill???

>I know the manual says that sig 9 may not be caught or blocked
>but I was wondering if there might be a funny (strange, interesting)
>hack to get around this...

I've seen situations in which the program is trying to write to some
device like a network socket or parallel or serial port, and there's
something wrong with the connection.  In this case, it frequently
happens that even kill -9 won't work; rebooting is the only thing *I*
can think of to do when this happens.  I suppose a program could do this
deliberately.

By the way, is there any *legitimate* reason for a device driver to
simply "hang" forever?  In other words, is this ever *not* a bug in
the device driver?