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From: bog@lynx.uucp (Bill O. Gallmeister)
Newsgroups: comp.unix.internals
Subject: Re: Signals queued or not? (POSIX note)
Message-ID: <8699@lynx.UUCP>
Date: 21 Feb 91 17:25:05 GMT
References: <7103@fs1.cam.nist.gov> <67880001@hpcupt1.cup.hp.com> <2519@inews.intel.com> <10007@dog.ee.lbl.gov>
Organization: Lynx Real-Time Systems, Trendy Los Gatos, CA
Lines: 23

torek@elf.ee.lbl.gov (Chris Torek) writes:
>(Blair P. Houghton) writes:
>>Not the least of those variances is that signals may be queued ....
>Signals are not queued.

While this is correct for most currently existing UNIXes, note that:

(1) POSIX 1003.1 allows signals to be queued (Section 3.3.1.2, line 463:
"If a subsequent occurrence of a pending signal is generated, it is
implementation-defined as to whether the signal is delivered more than once").
A POSIX.1-conformant system may queue signals.

(2) POSIX 1003.4 Draft 10 specifies Real-Time Extended Signals, a range
of signal numbers that _are_ queued.

Caveats/Asides:
1003.1 is an ISO standard.  1003.4 is being balloted.  Whether POSIX is
UNIX is a matter of debate.  But there are UNIX systems that queue signals.

-- 
Bill O. Gallmeister                                     Lynx Real-Time Systems
bog@lynx.com                                            Trendy Los Gatos, CA
               Things come with their being ready-made.                 


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