I was searching Unix vs OS X. I found a notable difference at From http://www.unix.com/unix-dummies-questions-answers/919-mac-osx-vs-unix.html

OS X is a evolutionary kernel from the MACH and BSD linage.

Can anyone help me understand this?

What are the notable differences between Unix and Mac OS X.


2 Answers 2


Regarding an explanation of the explanation:

See the FreeBSD forum. Basically the OS X userspace is essentially FreeBSD (with small elements of NetBSD) but the kernel itself is a fork of the MACH Kernel that makes it more monolithic in nature (like the network stack and process model are in line with FreeBSD). For a technical description, you'll probably have more luck googling "Darwin" than "OS X" since the latter has a lot of noise in it from people uninvolved with the project.


Need differentiate the points of views:

From the shell-users point of view here is no big differences. OS X is fully certified Unix operating system, so it's command line is fully compliant with Unix standards and POSIX. You have terminal with shell, all shell commands (BSD style), you can install e.g. macports for GNU-versions of commands. e.g. the bundled sed is without --long argumnets, when you install macports you will get gsed - the GNU version. You have common directory structure as /bin /sbin /usr/bin .etc..

From the X-windows-user point of view - you can use X-windows apps, but it is not the default GUI. OS X has own GUI (called Cocoa). For an good overview you shoudl read this developer doc.

From the point of view system-admin - here is some bigger differences. Many configurations are done with Apple's own tools (mostly GUI) - but all tool has comman line interface too - but is IS a bit different from common UNIXes.

The biggest differences are for developers. OS X using fully object oriented message passing Objective-C. The Mach kernel IS message passing oriented kernel. Developing with xcode (Apple's development tool) is really easy.

I'm after using many different unix flavors over the last 20+ years (starting with BSD 2.9 on PDP11, via BSD 4.2/VAX, XENIX, SCO Unix, Consensys, Linux and FreeBSD) now using OS X nearly ten years. IMHO it is the best UNIX what I used anytime - so therefore the answer is subjective...

  • +1 for "Many configurations are done with Apple's own tools (mostly GUI) - but all tool has comman line interface too - but is IS a bit different from common UNIXes." Commented Apr 22, 2013 at 5:52
  • 2
    note: the equivalent of X11 in OS X is Quartz. Cocoa is more like Qt or GTK+.
    – strugee
    Commented Feb 9, 2014 at 21:03
  • @strugee - ofc, youre right! ;) Here is an nice topic about the layers: developer.apple.com/library/mac/referencelibrary/GettingStarted/…
    – clt60
    Commented Feb 10, 2014 at 0:00

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