busbus wrote:OS X is based on FreeBSD which is more than "sort of" Unix.
Actually, it's based on NeXTSTEP, which was a variant of UNIX native to NeXT computers.
NeXT was the company Steve Jobs founded after he was kicked out of Apple in the mid '80s. NeXT machines were extremely high-end workstations (they cost upwards of $10,000 apiece) developed for and marketed towards universities, research institutes and large tech companies.
The NeXTSTEP filesystem was based on BSD UNIX, but its kernel was different. NeXTSTEP used the
Mach microkernel, a specially-designed, smaller and lighter replacement kernel for BSD UNIX. That microkernel architecture is now at the heart of OS X.
Linus Torvalds also based his Linux kernel on a microkernel design, a hobbyist's open-source OS called MINIX. So Mac OS X and Linux actually do have a lot in common.