OSX is Unix based?

So I heard this quote a thousands times: "OS X is a Unix based OS." and if it is so, doesn't it mean it is an open source OS and supposed to be free for anyone?
I am asking this just for my curiosity.

 

Unix is not open source. Linux is open source. Both Linux and OSX are derivatives of Unix, but the tree is so large that they're hardly similar.

http://www.levenez.com/unix/unix.png

Also, open-source free is not the same as doesn't-cost-money free.

 

Mac OS X 10.5 and 10.6 are UNIX... they are not just UNIX based, they are actually certified UNIX OSes.

Linux is like UNIX, but is not actually UNIX.

"UNIX" is not Open Source.... your just mixing that up with many OSes that are open source based on, or formed after UNIX.

Much of what Mac OS X uses actually is open source. The Darwin kernel even is and you can run it on different machines.

 

I guess you could say "Mac OS X is a Unix OS". It is licensed and conforms to the Unix OS specification. There are a variety of other operating systems which are also licensed and meet the same specification. Reaching a little further, there are "Unix like" or "Unix based" operating systems that at least partially implements the Unix specification, but are unlicensed / not certified, and cannot use the trademark name "Unix". These may be proprietary / nonfree or free / open source. Note that plenty of "free" software is still proprietary and closed source, and therefore is considered non-free from a licensing standpoint. People often use the expressions "Free as in free beer" to describe proprietary, closed software that doesn't cost anything and "Free as in Freedom" to describe completely free, open source software.

Mac OS X pulls a lot of their OS code from FreeBSD. FreeBSD is a free and open source Unix-like OS. It completely implements the Unix specification, it is Unix compliant, but it is not licensed to use the trademark name because they don't go through the certification process (difficult, expensive, changes frequently). Apple does put Mac OS X through the certification process, though.

Linux is another operating system specification that has its own standards, includes its own kernel, and is composed of free open source software, and those standards are largely the same as Unix. Sometimes the linux specification will extend Unix features or vary slightly. Operating systems that adhere to the linux specification may be free and open source or not, just like Unix.

 

There is no 'guessing'; it's a certified Unix;

Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc."

First line of the wikipedia entry- Mac OS X - Wikipedia, the free encyclopedia

Register of Open Branded Products

 

Also, Mac OS X wasn't always Unix certified.

You could say that it used to be a "Unix-like" OS and now is a recent Unix OS.

Only the intel variant of OS X 10.5+ is Unix certified.

I wasn't guessing whether or not the current incarnation of Mac OS X was unix certified. The only problem is calling "Mac OS X" unix certified, because you might be referring to the latest version, or maybe Leopard or Tiger, or maybe Mac OS X running on PPC, and those variables affect whether it is certified. The end.