How Unix is Mac OS X?
People always said ubuntu, linux is UNIX based OS, then how about mac os x? from mac os x terminal i can see most of the unix command are available does it mean mac os also built on UNIX?
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To be more specific, Mac OS X is built on Darwin---a derivative of BSD---running on a Mach microkernel.
Indeed it is:
As another poster stated it's also Unix certified: http://www.opengroup.org/openbrand/register/brand3555.htm
Mac OS X is a genetic UNIX (being a descendant of NEXTSTEP and ultimately BSD, a genetic UNIX).
It's also a UNIX-like OS (being UNIX-like).
See the relationship to UNIX and Linux here:
Note that Linux is UNIX-like but no genetic or trademark UNIX. Mac OS X is both a trademark and a genetic UNIX.