UNIX question

[Chris Torek]

In article <824 at brl-tgr.ARPA> lcc.rich-wiz at locus.ucla.edu (Richard Mathews)
writes:

>> From: Chris Torek <chris%umcp-cs.uucp at BRL.ARPA>

>> In V7, 3BSD, and 4BSD, and I suspect also in Sys III and V (and
>> Vr2 and Vr2V2), and probably in V8 as well, signals are not queued...

> In System V, SIGCLDs are queued (well, sort of).  See the signal(2)
> manual page.  In reality what Sys V does is this (at least on a VAX):

[description deleted]

In other words, System V arranges for the delivery of a SIGCLD, in
the process changing things back to SIG_DFL, so that that exactly
one is sent, and one more will be sent when the signal handler
restores SIGCLD catching if and only if there is at least one more
child process.  To put it another way, the signals themselves are
not queued, but child process exit is not the only trigger for
SIGCLD; exited children are already queued, so the effect is the
same.

Implemented properly, that will guarantee reliable operation.  Ok.
One down, 31 to go :-).  ---Signals, of course.  What else?  (Well,
all right, I will give them credit for not breaking everything in
the name of advancement.)
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 4251)
UUCP:	seismo!umcp-cs!chris
CSNet:	chris at umcp-cs		ARPA:	chris at mimsy.umd.edu