Yes, OS X is UNIX. Apple has submitted OS X for certification (and received it,) every version since 10.5. However, versions prior to 10.5 (as with many ‘UNIX-like’ OSes such as many distributions of Linux,) could probably have passed certification had they applied for it.

Is Apple a UNIX system?

It feels like the most modern of computers. But like the iPhone and the Macintosh, the Apple tablet revolves around a core piece of software that can trace its roots all the way back to the early 1970s. It was built atop UNIX, the operating system originally created over 30 years ago by researchers at AT&T’s Bell Labs.

Does Mac run on UNIX or Linux?

macOS is a UNIX 03-compliant operating system certified by The Open Group. It has been since 2007, starting with MAC OS X 10.5.