Path: utzoo!mnetor!uunet!husc6!cmcl2!beta!unm-la!unmvax!nmtsun!hydrovax
From: hydrovax@nmtsun.nmt.edu (M. Warner Losh)
Newsgroups: comp.lang.c
Subject: Re: exit(-1), 0 is sometimes magic
Message-ID: <1234@nmtsun.nmt.edu>
Date: 17 Jan 88 18:57:12 GMT
References: <502@cresswell.quintus.UUCP> <6935@brl-smoke.ARPA> <1179@wjvax.UUCP> <2305@bloom-beacon.MIT.EDU>
Organization: NMT Hydrology program
Lines: 25
Keywords: exit, zero, flaming
Summary: Isn't OS specific, it's shell specific.

Mark Eichin write that using exit(0) is OS sepcific, when in fact
it is ENVIRONMENT specific.  True enough that all of the SHELLS
that UN*X uses use an exit status of zero to mean success (at least
all of the one's that I know of).  It is the SHELL, NOT THE OPERATING
SYSTEM, that is the factor here.  If you were programming on VMS, where
you could have the dcl shell (or more correctly (from a VMS point of view :-),
command interpreter [sic on spelling]) that treats an exit status of
on ODD number as success, and an EVEN (for error, I quess) number as
an error.  On the same machine, running the same OS, you can also have
DEC/Shell, which assumes a more "unix" oriented posture.  That is, it
expects the "exit(0)" convention.

As a side note.  exit(0) in UNIX isn't quit correct.  The UNIX shell,
as far as I know, doesn't give a hill of beans wheather you say exit(0),
exit(1000), exit (magic_number)....  It is the SHELL SCRIPTS that people
write that impose this "standard" upon UNIX.  I could be wrong about
this, but I seem to remeber reading in one of the books/manuals/mag
articles about unix that this was the case.  I know it's common practice,
but is it required?  Plesae resond only if YOU KNOW FOR SURE.
-- 
bitnet:	lush@nmt.csnet			M. Warner Losh
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