DIFFERENCES BETWEEN S5 AND 4.2?

[gwyn%brl-vld at sri-unix.UUCP]

From:      Doug Gwyn (VLD/VMB) <gwyn at brl-vld>

It is interesting that you have drawn your conclusion (that you need a
4.2BSD UNIX rather than a UNIX System V) in advance of having the facts
you need to back up your conclusion..

The only practical way I know of to develop software under 4.2BSD for a
UNIX System V destination is to have a very complete UNIX System V
emulation running on top of your 4.2BSD.  The systems differ in too many
ways to share common source code if you need to use ioctls or signals in
non-trivial ways.  There are ways of isolating such system dependencies
in small "interface" source files, but you would still need to test your
interfaces for the other system somehow..

Fortunately there is a public-domain (except of course for an AT&T UNIX
license requirement) emulation of UNIX System V available for VAX
4.2BSD.  I will mail you the blurb I posted to the UNIX-Wizards mailing
list; anyone else who is seriously interested in this package can send
mail to gwyn at brl-vld.arpa or {decvax,esquire,research,unc}!brl-bmd!gwyn
and I will send you a description and details on how to obtain the tape.

If it weren't for the comfort of a UNIX System V environment, I wouldn't
be able to stand developing software under raw 4.2BSD.  I also enjoy
having exactly the same source code across all our flavors of UNIX.