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From: gwyn@brl-tgr.ARPA (Doug Gwyn <gwyn>)
Newsgroups: net.unix
Subject: Re: BOOKS: Advanced UNIX(TM) Programming
Message-ID: <188@brl-tgr.ARPA>
Date: Fri, 29-Nov-85 23:13:50 EST
Article-I.D.: brl-tgr.188
Posted: Fri Nov 29 23:13:50 1985
Date-Received: Sun, 1-Dec-85 03:13:30 EST
References: <672@hou2a.UUCP> <292@l5.uucp> <152@brl-tgr.ARPA> <5299@elsie.UUCP>
Organization: Ballistic Research Lab
Lines: 27

>  For portability, one should be programming
> in what's common to System V and BSD.

That's nice when you can arrange it, but the "lowest
common denominator" is pretty low indeed.  One problem
with the /usr/group Standard was that it often settled
for the lowest common denominator of systems like 7th
Edition, Xenix, System III, etc. and this meant omitting
altogether the terminal handler ioctls and so forth.
Real applications need a higher level of support than
that, so for maximum effect a portable environment needs
to be more than whatever is common across UNIX variants.
IEEE P1003 is aware of this and are trying to establish
a sufficiently high-level standard system interface.  It
happens to be based on System V, but so far it has not
ruled out implementation on 4BSD kernels.  One hopes at
some future date the standard interface will be provided
automatically by most UNIX system vendors.

Meanwhile, there shouldn't be much work involved in
adapting the BRL UNIX System V emulation for 4.2BSD to run
on 4.1BSD.  Few of the new 4.2BSD features were used;
indeed, quite a bit of the emulation is there just to work
around things like the new signal behavior, so one could
just remove that and use a direct interface for 4.1BSD.
If someone has done or wants to do this work, I would be
glad to give technical advice and to distribute the result.