What is UNIX, Anyway?

Lieutenant writes "Technology professionals have loosely used the term "UNIX" since the first person had to explain the difference between the Berkeley and AT&T flavors, so it's not surprising to find as many UNIX standards as there are versions of the operating system. Peter Seebach wades through the wellspring of UNIX standards and sorts them out for you, concluding that the rumors of the death of UNIX are (as usual) greatly exaggerated."

Comments

Single Unix Standard, Version 3

[Gopal.V]

As a programmer, that's what I really consider as Unix - sus v3.

I code for this API and the sources end up being source compatible. But then there are library paths and stuff, which is why even something as homogenous as Linux is forced to create LSB standard. The API standard OTOH, is crystal clear - look at the API tables in terms of availability. And yeah, my project is called Portable.net, so I've put in my time writing portable code for various platforms (even BeOS and SkyOS). Wish the threading models worked the same, that's all :)

There is just *nix ... just *nix and VMS - everything else is somewhere in between.

Re:Single Unix Standard, Version 3

[Anonymous Coward]

Well, that's certainly a negative way to put it, but what if anything could they do any better? It's not like it would be particularly practical or reasonable for unix vendors at this stage of unix history to break backwards compatibility for the sake of future compatibility.

So, the unix vendors do the next best thing: they make whatever changes they can to bring their platforms to uniformity without breaking backwards compatibility, and they maintain a common standards document that documents the cross-platform compatible functionality. When they inevitably make mistakes in the documentation process, they remove specifications that they cannot implement complatibly in all unix systems.

The most important point here is the intent of the unix vendors: They are working towards compatibility wherever they can, and they are striving for accurate documentation of the compatible functionality. There's nothing to disparage in their actions, even if they make the occasional mistake -- at least they are improving all the time.

Even linux developers are known to deviate from the SUS occasionally, but they too do strive to implement the standard wherever possible. Yes, the Single Unix Specification is incomplete and flawed, but it's the best thing we've got.

First Sale Doctrine

[David Hume]

FTFA:

A single programmer who wants a copy of the POSIX specification would have to pay US$974 for it. That gets a one-year subscription; you are not licensed to continue referring to the standard thereafter.

What about the first sale doctrine? Do they really contend that you cannot "refer" to the standard after one year? Do they do a mind wipe? Or is just that your subscription for updates lapses after one year?

The Spirit of UNIX

[murdie]

Probably the oldest standard that people still refer to is AT&T's 1985 System V Interface Definition (SVID).

I routinely use printed Seventh Edition (Bell Labs Research) UNIX manuals, even when writing C for Linux. It also helps one remain blissfully ignorant of the 'cat -v' option and similar excrescences. Also the Tenth Edition UNIX manuals. I have to remember the changes introduced by Standard C and the like, but it's convenient to have the essence of the modern-day manual in printed form. Of course, there are some people out there who delight in using Fifth, Sixth, Seventh etc Editions on PDP-11s etc - see the PDP-11 UNIX Preservation Society, http://minnie.tuhs.org/PUPS/. I wish I had a larger garage! How much would a PDP-11/40 cost me now, anyway?

Peter Salus' book "A Quarter Century of UNIX", Addison-Wesley, 1994 (corrected 1995), ISBN 0-201-547771-5 is a good informal UNIX history.

"Those who do not understand UNIX are condemned to reinvent it -- badly."
                                                  -- Henry Spencer