hm... depending on your system, this may or may not be a
trivial thing to implement. now, i am working on old memories
i don't really have any more, but if i remember correctly,
a lot of modern OS's will have variable sharing via shmget
and shmput and other such LOW level system calls, however
depending on the cleaness of the semaphore calls, and the
guarantee of atomicity of update, this may become a very
difficult thing. We've had very limited success with the
IPC shared cache and IPC sharable modules from CPAN, because
they do a serialization of data structures, which if you
are in a speed quasi-critical enviroment, it becomes a
cost prohibitive operation... again, if you must have
shared variables (and make sure you understand why you
have to have them... they may not be neccessary, and it
may be easier to retain state in some other daemon which
you poll via a pipe or something along those lines...) the
CPAN modules will really help you out.