What Is This Thing Called Unix

The term Unix has come to mean several things:
  1. It is an operating system originally created by Bell Labs.
  2. It is any one of several operating systems that are 'certified' Unix� by TheOpenGroup?.
  3. It is an operating system that seems sufficiently UnixLike.

What are the features that make an operating system 'feel' like Unix? What are the elements of an operating system that are generally recognised as Unix?
Elements which make Unix Unix:
I can remember when Unix began to be commercial. In the early 80's a friend of mine became a dealer for a line of Unix machines made by AT&T. I remember playing with it. It seemed OK for awhile, but then I discovered that it didn't have grep. "No grep?", I said. "This isn't Unix!". It was at that moment that I discovered that one of the features of any Unix was that it had grep. In this case, the OS in question was Unix with a bunch of "developer tools" removed. If you remove the C compiler from Unix then it can still be Unix, but if you remove grep then it isn't.

Of course, just putting grep on a computer doesn't make it Unix. The qualities that make a operating system Unix are mysterious.

I started using Mac OS X a couple of weeks ago. It is very nice. It is built on top of Unix, but it isn't Unix. For the life of me, I can't find the command prompt, though I know it is here somewhere. It is a very nice Mac OS, and it might be Unix compatible, but until I find the command prompt, it isn't Unix.


Open a finder and navigate to Applications->Utilities from the root of your installation partition. For convenience, drag the Terminal app onto the dock.

I've Mac OS X running on this PowerBook, and with the Terminal app in the dock it feels almost as much like Unix to me as does Solaris (with CDE) running on the SPARC box next to me here. Is OS X really "built on top of" unix? There's a BSD-like environment running, but nothing else in the system seems to rely on it being there, does it? Lots of things that Darwin does it does in a unix style, for sure, and that makes it a comfortable environment for unix-mined folk. I'm both pleased and impressed by the way that the rich Mac OS gui is there when I'm feeling point-and-click ish, or want to multi-media sort of things, and the command line is there when I want to type. And I can do many of the same things with either (though some things more easily with one that the other, of course) as I wish without them getting in each other's way significantly. --KeithBraithwaite

The Terminal Program in MacOsx pulls away the curtain and reveals that MacOsxIsUnixBased. Under the hood you have Apache, Emacs, Vi, a C compiler, Perl, etc. I've even built Unix/Linux programs (eg. Python) ported to MacOsx with trivial ease. --SeanOleary

More things I require in a Unix qua unix
CategoryDefinition CategoryUnix

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