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  From: Greg Lehey <grog@lemis.com>
  To  : David Lloyd <lloy0076@rebel.net.au>
  Date: Fri, 9 Jun 2000 16:45:47 +0930

Re: [OT] The UNICES

On Friday,  9 June 2000 at 14:22:44 +0930, David Lloyd wrote:
>
> I understand that there are two main divisions of UNIX, although someone
> who understands one of the divisions will understand the other. The
> division I'm talk about are:
>
> * BSD Style Unix
> * System V Style Unix

Well, there's also the original UNIX, Research UNIX.  It is no longer
being developed, but it was until about 1990.

> I understand the main difference is the code base.

Hmm.  Maybe.  They share a lot of common code base.  The "main
differences" are more difficult to quantify.

> I also understand that there is a standard called:
>
> * POSIX
>
> Now, I have a few questions:
>
> 1. Out of the BSD and Sys V Unices, which one is chronologically
>    older?

BSD.  It's derived from the Sixth Edition Research UNIX (1976), while
System V is derived from the Seventh Edition (1978) via System III.
The first BSD UNIX to be considered a separate development is probably
3BSD (1979), while System V(.1) didn't come into being until about
1983.

> 2. Are they SO different you are forced to learn one rather than the
> other...or are they so similar that there really isn't much of a
> difference to the END user (not the person who is doing the
> programming)?

No.

There are differences, some of which are more than the differences
between Linux and either of them.  There are also differences between
the System V dialects, and there are differences between the BSD
dialects.

> 3. If there is a difference, is there a consensus as to which one is
> better as measured by:
>   i) stability
>   ii) efficiency
>   iii) security
>   iv) ease of administration

No.

> 4. There must be a relationship or some type of link between the BSD
> Style Unices, System V Style Unices and POSIX. What is this
> relationship?

It's difficult to say.  Note that POSIX.1 is a very primitive
standard; a system which implemented only POSIX.1 would not be usable.

> 5. Is Linux compliant with any of the above standards?

It's relatively faithful to POSIX.1, though of course it adds a lot
more (see 4).

> 6. If one could administer a Linux System, such as one based on RedHat
> 6.2, by command-line, could one with only minimal learning but no
> experience, administer an enterprise Sun Solarise or HP-UX or IBM AIX
> machine?

For a certain definition of minimal, yes.

> 7. Out of the following UNICES, which one is which standard? I'm going
> to try and divide them into the right groups as I think but I'm not
> certain:
>
>   * SYSTEM V: Sun OS, Sun Solaris and IBM's AIX

The only pure System V there is Solaris (really called Solaris II or
SunOS 5).  SunOS (really SunOS 4 or Solaris I) is almost pure BSD.
AIX has a bit of both.  So I'd say Solaris II here.

>   * BSD: HP-UX, Free/Open/NetBSD and BSD (is there such a beast?)

HP-UX is part BSD, part System V, rather like AIX.  FreeBSD, OpenBSD,
NetBSD and BSD/OS (from BSDi) are all very similar to each other, much
more so than the others you mention (though SunOS 4 comes close).

> 8. Of System V and BSD, which one is Linux most similar to or fully
> compatible with (if that's the case)?

That's not really the case.

> I'm sorry that these questions sound like text book questions. They're
> NOT. I just want to brush up on some UNIX history and standards and work
> out which UNIX stands where, or which UNIX like operating stands where
> and such.

You might like to take a look at
http://minnie.cs.adfa.edu.au/Unix_History/index.html.  I'm also
attaching a BSD family tree which also contains a number of other
references.  Sorry I can't find a single page one for all of UNIX, but
if you get your hands on "The Design and Implementation of the 4.3BSD
UNIX Operating System" or "The Design and Implementation of the 4.4BSD
Operating System", there's a reasonable overview in the first chapter.

Greg
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