Title says it all.
Linux is not certified by Unix? It´s not a family with Unix? Why AIX and MAC os are certificated and Linux not?

Why? Because is linux is open source, and MAC and AIX are closed sourced "clones," per say. Hence, not open source.

As I understand it, it's mainly about money.
http://en.wikipedia.org/wiki/Single_...fication#Other
I also think there's the question of lineage, with Linux being written from the ground up rather than sharing a base with Unix in the way that AIX, BSD and OSX do.

http://en.wikipedia.org/wiki/Unix

In summary, AIX and MacOSX can call themselves UNIX because they paid for certification from The Open Group, who own the UNIX trademark.

Also, keep in mind that the definition of 'Linux' varies somewhat. It can mean several things, e.g. just the kernel (which couldn't pass certification on its own) or a collection of different distros based on this kernel (which have different collections of components). When you certify that your OS is UNIX you need to provide a specific version, which is why MacOSX has been recertified with each new release.

That said, if they cared to pay for it I wouldn't be at all surprised if a Linux disto like say Red Hat Enterprise Linux 6 could pass certification with minimal (if any) changes but even if this was done it would not grant all Linux distros the right to call themselves UNIX, just that particular version of that particular distro. A series of minor versions (e.g. Red Hat 6.X) might be similar enough that recertification could be avoided but major changes may mean that they need to apply again.

What does certification gain you? Two things, it means that a software vendor making UNIX compliant software can be fairly certain that their software should compile and work on that Operating System and there is also the bragging/marketing rights that the Operating System is 'UNIX' (which carries some weight in the business world).

Is it worth the time and money for someone like Red Hat to do this? No probably not any more, as the Red Hat and Linux names probably carry a similar level of marketing weight on their own these days and most commercial vendors making 'UNIX' software already consider Linux.

Finally, it is worth noting that FreeBSD, Darwin and OpenSolaris/Solaris Express are not officially UNIX either, since they too lacks certification. This is despite the fact that they share some source code with official UNIX OSes. Some FreeBSD code was taken into Darwin and Darwin forms the basis of MacOSX. In the OpenSolaris/Solaris Express case it is a direct descendant of the UNIX System V Release 4 code base. However the certification process does not care about these historical links.

In the case of FreeBSD, again its own brand is strong enough that it probably shouldn't bother 'wasting' FreeBSD Foundation funds on obtaining official UNIX certification.

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Lineage doesn't matter at all, which is why FreeBSD, OpenBSD, NetBSD, DragonFlyBSD, Darwin or even OpenSolaris/Solaris Express are not UNIX either.

You might also want to read the The Open Group's "What is UNIX ®?" page and their list of products that have certified to various UNIX product standards.

EDIT: It is interesting to note that Solaris 10 is listed multiple times under UNIX 03. One of the times was by Fujitsu Limited, rather than Oracle Corporation. Presumably slight changes for each platform meant that recertification was required. This demonstrates that you could never certify 'Linux' as UNIX, it would have to be a release of a specific distro.

It doesn't matter as far as certification is concerned, no. But unofficially at least you often see the BSDs described as Unix but Linux is always Unix-Like. I thought the original question alluded to this a little so thought it worth mentioning (since the Wikipedia link shows BSD and Linux's status).

Sure people called them UNIX but it is not true in a legal sense. It would certainly be trademark infringement for any of the BSD derivatives to call themselves this without obtaining certification and hence is IMHO a mistake even for an individual to label them publicly as UNIX.

By the way this wasn't meant as some kind of insult to BSD. There is no shame in it. I honestly don't think the certification is worth the time or the effort given the strength of the 'BSD' brand in its own right.

I think the situation is confused (and I didn't help it) because AIX, BSD and OSX can all claim to be from the "Unix Family" as they're in some way traceable back to the origins of Unix.

Exactly. Hence why with linux, all open source, free, etc. With Unix on the other hand, it is more closed source, so you can technically market it, like with OSX, etc.

There are actually some very few but important technical issues between the two. Not sure linux could ever become fully unix certified.

This goes all the way back to The SCO Group's spectacularly unsuccessful attempt to sue IBM and everybody-else to pay royalties for the use of anything-and-everything that (according to SCO) smacked of "Unix." This long-running lawsuit was documented in grueling day-to-day detail at http://www.groklaw.net, even as it permanently transformed the career of the paralegal who originally started that site.

"Frankly, my dear, nobody gives a damn" about "Unix certification." The pragmatic business fact of the matter is that open-source Linux legally supplanted the former place of Unix in the marketplace, even as SCO's foolish and tenacious lawsuit drove a coffin-nail into any lingering notions that any business arrangement other than legally-enforced open source (i.e. "cooperative") development would be suitable in the context of what Linux is today called-upon to do.

When you consider that the Android operating-system is a Linux-based distribution ... "I rest my case." 17 million mobile devices were activated last Christmas Day, and about 50% of those were Android-based. Furthermore, since at least the core of Apple's OS/X system is also open-source, "Darwin," well, "there's the other half, too." The market has spoken, the future is here, and anything related to the Unix trademark which somebody paid much too-much money for is ... irrelevant.

(Too bad you spent so much money on lawyers, SCO ... you bankrupted yourself, "thou fool.")

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Yeah but it isn't the fact that they are Open Source that they are not UNIX. Someone could choose to pay for certification of OpenIndiana and it would probably pass given its similarities to Solaris but it would still remain Open Source. My point being that technically there is no reason we couldn't have an UNIX certified Open Source OS. Nobody seems the benefits however in comparison to the price.

Yah, just like red hat; Red hat is free, but it's the support you are paying for. Quite smart, I'd say so...

I looked also information who uses Linux and Who uses Unix, and tendence is to use Linux.
So as you said, Unix certification is not so important as I thought.

Look that:

and that:

(How many servers in the world are there with Windows. Somebody knows that?)


So now I understand that now, 2013, Linux is either more important then Unix.



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http://www.diffen.com/difference/Linux_vs_Unix