signals to running processes

[Guy Harris]

>That may very well be, but I was simply trying to state that
>if he does not have System V, chances are he won't have *shared
>memory*.

Again, not so fast; if you have "shmat", which is what I was "grep"ping
for and found in the SunOS "lint" libraries, you presumably have
"*shared memory*" - the "shmat" I'm familiar with is, from the SunOS
manual page:

     shmat() maps the shared memory segment associated  with  the
     shared  memory  identifier  specified by shmid into the data
     segment of the calling process.  Upon successful completion,
     the address of the mapped segment is returned.

These days, I would think twice before saying "if he does not have
System V, chances are he won't have *shared memory*", if "System V" is
to be interpreted as "something that began as the stuff from an AT&T
source tape, as you seemed to have interpreted it.

Looking at the value of SIGUSR1, seeing that it's not 16, and concluding
that they're unlikely to have shared memory is a mistake; if they *do*
have a system that started out with the stuff from a Berkeley source
tape, but that had S5 IPC added, and took the claim that they were
unlikely to have S5 shared memory at face value and didn't look for it
on their system, they'd have lost.

The world isn't neatly divided into "BSD" and "System V"; there are
plenty of systems with features from both, many of which may have
started from BSD but picked up stuff like S5 IPC.

(Of course, in SunOS - and, I think, in at least some other systems,
including S5 from AT&T - it's an optional feature, so you have to
configure the S5 IPC stuff into your system.)