Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!yale!cmcl2!kramden.acf.nyu.edu!brnstnd
From: brnstnd@kramden.acf.nyu.edu (Dan Bernstein)
Newsgroups: comp.unix.programmer
Subject: Re: Catching termination of child process and system() call
Message-ID: <12673:Feb1900:07:4691@kramden.acf.nyu.edu>
Date: 19 Feb 91 00:07:46 GMT
References: <1356@geovision.UUCP> <9882@dog.ee.lbl.gov> <2608@root44.co.uk>
Organization: IR
Lines: 22

In article <2608@root44.co.uk> gwc@root.co.uk (Geoff Clare) writes:
> The discussion does have some relevance to 'C' since
> it is about the format of the status returned by wait(),

No. It has absolutely nothing to do with C. We just happen to be talking
about it in C.

> POSIX does not specify the precise encoding of information in the status
> returned by wait(), system(), etc., so portable programs should not
> rely on the traditional encoding Chris describes above.  Instead macros
> are provided in <sys/wait.h> to extract the relevant data from the status:

Wrong. A program written according to your advice is decidedly
nonportable: it will work only on POSIX systems. A program written
according to Chris's advice will work under System V, BSD, and most
POSIX-based systems to boot. Someone who wants to plan for the future
should conditionally compile the POSIX code, though of course he'll
still have to use w & 0200 to get the core dump bit.

Portability is defined by the real world, not a standards committee.

---Dan