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From: gm@mitisft.Convergent.COM (G.M. Harding)
Newsgroups: comp.software-eng
Subject: Re: VMS vs. UNIX s/w development tools - query
Keywords: VMS, UNIX, tools
Message-ID: <606@mitisft.Convergent.COM>
Date: 6 Apr 89 18:45:01 GMT
Organization: Convergent Technologies, San Jose, CA
Lines: 43


In article <7036@pogo.WV.TEK.COM> rickc@pogo.WV.TEK.COM (Rick Clements) writes:

> But, doesn't 0 indicate
> not finished to VMS?  A value greater than one indicates an error.
> Passing a 0 back from a VMS driver will crash your program (80% of the
> time), work ok (15%) and crash the system (5%).  These are estimates
> based on the experience of my self on others at a previous company.

     The last time I used VMS (4.3? 4.4? Am I thinking of some other
software product?) code ported from Unix with a standard "return (0)"
at the end of main() would cause VMS to display a particularly
unaesthetic error message on the screen at process termination.
The system did not, however, crash or otherwise behave abnormally.
Perhaps zero has the connotation you mention at the driver level,
but I don't think such is the case at the application level. The
way I discovered what was happening was peculiar: I noticed that
the VMS termination-error message went away if my program had an
internal error! In that case, it would return 1 from main(), which
VMS thought was just fine.

     The Unix convention on process-termination values makes a lot
of sense. Think about it: There are many flavors of failure, but
there's only one variety of success, namely, the complete kind.
So, the Unix shell correlates the process-termination value with
the question: Were there errors? If the termination value is
logically TRUE, the answer is "yes"; otherwise, "no."

> File types are a problem in VMS. There are a lot of them. The default
> type for a C program is different than the default type for FORTRAN.

     This underscores the point I was making in my original reply
to the fellow who asked for an OS comparison. The system has no
business knowing (or thinking it knows) what's in my files. When
OS writers try to do cute things like that, they throw device
independence out the window. (Notice that nobody has ever accused
VMS of being based on the spirit of device independence. Ever try
to mount a tape on VMS?)
-- 
G. M. Harding                      /* * * * * * * * * * * * * * * * * * * * * *
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