I am currently enrolled in a course that is teaching me UNIX fundamentals, such as common commands and such. After doing some digging on UNIX, I came across the rabbit hole of legal battles over who owns UNIX, and the UNIX wars. I have done some research, but the sources are sort of dated (circa 2003 - 2004) and have conflicting information as far as who owns it.

Here are a couple of the sources I have found:

https://www.zdnet.com/article/who-really-owns-unix/ - states that the Open Group owns it

https://www.informit.com/articles/article.aspx?p=175171&seqNum=2 - states that the SCO owns it

After reading these sources, it sounds like the Open Group is claiming to own the UNIX trademark, while the SCO claims to own the UNIX source code. Am I understanding that correctly?

  • 1
    Which Unix, there are many. fosslinux.com/44623/top-unix-based-operating-systems.htm Shows top ten.
    – oldfred
    Aug 31, 2021 at 22:39
  • @oldfred I'm guessing just the aggregate of most UNIX flavors, like who owns the most UNIX variations. Aug 31, 2021 at 22:58
  • 2
    Each version is owned by the company that licensed it. Even Microsoft still owns its version. There is no one Unix. But as you mentioned there is a standard that companies have to meet to call it Unix.
    – oldfred
    Aug 31, 2021 at 23:09
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    @oldfred the OP is asking about the UNIX specification, not the implementation
    – phuclv
    Sep 1, 2021 at 12:30
  • 1
    @SentientFlesh yes but who owns the standard? That's what the OP is asking. Obviously implementations are only certified. They or their implementers can't own the standard
    – phuclv
    Sep 2, 2021 at 7:39

3 Answers 3



As of today, and talking about the USA, the UNIX trademark is owned by The Open Group (you can see it on the USPTO website) for "COMPUTER PROGRAMS, * NAMELY, TEST SUITES USED TO DETERMINE COMPLIANCE WITH CERTAIN SPECIFICATIONS AND STANDARDS *" (First use: Dec. 14, 1972, Use in Commerce: Dec. 14, 1972)

A bit more

Novell transferred the trademarks of Unix to The Open Group in 1993. See message from Chuck Karish on comp.std.unix news group. I quote a piece:

Q4. Will Novell continue to control UNIX?

A4. No. From today, the APIs which define UNIX will be controlled by X/Open and managed through the company's proven open industry consensus processes. Novell will continue to own one product (a single implementation of UNIX) which currently conforms to the specification. Novell is clearly free to evolve that product in any way that it chooses, but may only continue to call it UNIX if it maintains conformance to the X/Open specifications.

SCO tried to buy UNIX from Novell (again). You may read docketing statement of The SCO Group, Inc. v. Novell, Inc case. I quote a piece:

It is therefore ORDERED that SCO’s Renewed Motion for Judgment as a Matter of Law or, in the Alternative, for a New Trial (Docket No. 871) is DENIED. DATED June 10, 2010. BY THE COURT: TED STEWART United States District Judge

Then SCO appealed:

Party or Parties filing Notice of Appeal/Petition: The SCO Group, Inc. ______________________________________________________________________ I. TIMELINESS OF APPEAL OR PETITION FOR REVIEW A. APPEAL FROM DISTRICT COURT

  1. Date notice of appeal filed: July 7, 2010

On August 30, 2011, the Appeals Court affirmed the trial decision. You can read this. A quote:

VII. IMPLIED COVENANT OF GOOD FAITH AND FAIR DEALING SCO argues the district court erred in entering judgment in Novell’s favor on its good faith and fair dealing claim (...). The district court’s conclusion on this point is consistent with the jury verdict on copyright ownership and is supported by evidence in the record. AFFIRMED. Entered by the Court: Terrence L. O’Brien. United States Circuit Judge

So Unix is not owned by SCO. In fact, SCO holds some UNIX® certifications issued by The Open Group: UNIX 95 and UNIX 93.

Any system that wants to be called a UNIX® must be certified by The Open Group. A list of certified Unixes can be found on The Open Group official register of UNIX Certified Products page. Some related systems not holding a certification are usually referred to as *nixes or Unix-like systems.

You can find out more on Wikipedia article about UNIX, section Branding and article about SCO Group, Inc. v. Novell, Inc. lawsuit.

  • 9
    @Ultracrepidarian In case you're wondering why companies still pay The Open Group for Unix certification, some US government contracts specify Unix as a requirement. This allows companies like Apple or HP to bid for those contracts. For OSes that cannot be certified as Unix like Windows there's POSIX certification (again, by The Open Group) and some US government contracts have lowered the Unix requirement to POSIX compatibility allowing things like battleships to run on Windows.
    – slebetman
    Sep 1, 2021 at 12:55
  • Great answer. Very complete! Thank you.
    – Scottie H
    Sep 1, 2021 at 13:41
  • in the past week there was some further news about the SCO lawsuit so that information might be germane to your answer. Sep 1, 2021 at 13:51
  • @TrevorBoydSmith do you have any sources? AFAIK the case was closed.
    – D4RIO
    Sep 1, 2021 at 15:13

Some Thoughts on Ownership

There is a difference between what people may call UNIX because of the Copyright ownership on the source code that allows to control what may be done to the source code and the ownership on UNIX trade mark that allows to control who may call a system a UNIX system.

Let me call the first one genetic UNIX wand the second one legal UNIX.

genetic UNIX

A genetic UNIX is a UNIX that is derived in a direct line from the AT&T UNIX that started 52 years ago in 1969. While some companies may call their product such a genetic UNIX, only two of these companies own the Copyright on that code in a way that they are allowed to control who may see, publish or modify that code.

One company is SCO and SCO used their rights to publish the historic UNIX sources to everyone.

The other company is Sun Microsystems and Sun used their rights to make the modern variant of SYSVr4 open source under the CDDL license. In 2010, Sun has been acquired by Oracle, so that Copyright owner now is Oracle.

Both companies have approx. equal rights on the copyright of that code. SCO of course has no rights on the modern code in SunOS.

legal UNIX

Since the mid 1990s, the trademark UNIX was transferred to The Open Group.

Since 2001, The Open Group also controls the POSIX standard and there is a difference between a pure POSIX system and a UNIX system.

This difference is based on decisions from around 1992, where several entities decided that a pure POSIX system is not sufficient as the base for computers with sufficient usability. These entities e.g. are governmental sites.

If you look at the POSIX standard, you can see what exact difference between a pure POSIX system and a system that may be called UNIX is.

Look e.g. at the definitions for echo and check for the parts of the standard that are XSI shaded. An operating system that correctly implements all XSI extensions is permitted to be called UNIX if it also passed a related certification by The Open Group.

There is a nice anecdote related to that trademark issue: Apple called their system a UNIX system without having a UNIX conformance certification and was sued by The Open Group to get that certification.

  • 10
    And then there's "philosophical Unix" which shares the philosophy and significant portions of APIs, but never sought certification nor is derived from the original code. Sep 1, 2021 at 10:42
  • 2
    @JörgWMittag Is that where Linux fits in?
    – Barmar
    Sep 1, 2021 at 14:18
  • 5
    @Barmar: The wonderful thing about philosophy is that we can argue endlessly about this question :-D I think we can all agree that this was the original intention. And in fact, there are Linux distributions that have been (legal) UNIX certified. Sep 1, 2021 at 14:23
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    The OP is not philosophical. Asking "Who owns unix in 2021?" is pretty straightforward. SCO owns just what Novell owed: the rights on a single implementation of UNIX, just code with no Unix branding. Anyways, that is not UNIX, but A UNIX. SunOS is a BSD branch, not Unix. This is not a question about what do you call Unix, but about who owns it.
    – D4RIO
    Sep 1, 2021 at 15:11
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    @TrevorBoydSmith, it's certified, then it's qualified to use the UNIX trademark (not Unix-like, but UNIX®).
    – D4RIO
    Sep 1, 2021 at 18:15

the SCO claims to own the UNIX source code. Am I understanding that correctly?

Ownership of the source code is more complicated than that.

The Santa Cruz Operation (the original SCO) no longer exists. They were a Unix licensee who subsequently bought some substantial controlling rights to Unix from Novell who had bought those rights from Unix Systems Lab (USL) at AT&T.

The Santa Cruz Operation sold most of their Unix IP and business to a Linux business named Caldera Inc who subsequently used the SCO name in various forms, mostly ending up named TSG (The SCO Group, bad SCO). TSG went bankrupt.

The current "owner" of the ancestral Unix code base is Xinuos. I believe they were formed (as Unxis) to buy from bankruptcy the remaining rights to market and develop the ancestral Unix code.

If you visit the sco.com website and click a few links, you will find yourself at the xinuos.com website.

There were other licensees of USL's Unix source code who had the right to independently develop and market Unix under other names (AIX, HPUX, Ultrix, SunOS, etc) - those are effectively forks of the ancestral Unix code base but, at least back in the day, were not regarded as the primary source of Unix. They were more like subsidiary forks of the code. Branches of the main trunk. In many cases with very substantial improvements.

See What is Unix now?

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