And Unix Begat Unix

- - posted in Ancient Archives

Arteth asked me for some links to Unix history info, and information on the different types of Unix available. My original email got a little too long, with more text than links, so I’ve posted it here. This is rushed and not particularly good, but it’s got the basic facts. No dates or quotes or references, just some quick notes.

Commercial Unix The “original” Unix operating system was sold and licensed many times, and kept splitting up into more and more versions, made by many companies. Most of those small commercial Unixes have now died out. Many were made only for hardware that is no longer sold.

These OSs are “real” Unix, descended from the original, and often very expensive too:

  • Solaris is Sun’s own Unix. Solaris is very strong in big business for servers and science workstations. Solaris is the most popular “true” Unix.

  • IRIX is Silicon Graphic’s Unix. Widely used for 3D graphics work on SGI workstations and servers for film and TV work.

  • AIX is IBM’s Unix. Used on very big computers and a few workstations.

  • HP-UX is Hewlett Packard’s Unix. Not so common, but still around.

  • QNX is an independant, ìrealtimeî Unix designed for embedded and research applications. Very fast, very efficient, and very reliable.

  • BSDi is an independant Unix for PCs. Very close to the old BSD Unix.

Free Unix The BSD code was opened up and given away. Many completely free BSD “Unixen” have developed from this original code over the last ten years or so.

  • FreeBSD is mainly PC based, and was the most popular of the free BSDs. It is the main rival to Linux. It has a huge library of easy to install software, and many users.

  • NetBSD is similar, but development is focused on getting it to run on as many hardware platforms as possible. It runs on just about everything, even very old computers.

  • OpenBSD focuses on security. It is probably the most stable and secure OS available. They’ve only had one security problem in five years.

  • Darwin is Apple’s BSD Unix, closely related to FreeBSD, but with many differences. Darwin is half of Mac OS X, but is available separately for free.

GNU (GNU’s not Unix) The GNU project aimed to replace the (proprietary and very expensive) BSD Unix system with a truly free alternative. They started with replacements for the tools and software, and then moved on to designing their own kernel. The GNU tools mimick the BSD Unix tools but there are differences - some extra features, some missing features.

In the meantime, a Unix-like OS kernel called Linux was started by Linus Torvalds. When combined with the GNU software, users could have an entirely free Unix on their own PC. This distracted developers from GNU’s own kernel, HURD. The GNU/Linux combination has become incredibly popular and successful in only a few years.

  • Linux, the famous Unix. The are hundreds of versions of Linux. Some are intended for use in servers, some are designed for desktop use, some run on PDAs. There is even a wristwatch that runs Linux. Some TVs and cars run Linux. Thankfully there are very few compatibility problems between different Linuxes.

  • HURD is still developing slowly, but is reaching a stage where it is usable. It has lots of radical features, while still recognisably a Unix -like OS.

Strictly speaking, HURD and Linux are not Unix, they are Unix clones.

Almost but not quite Unix There are also some other OSs that are similar to Unix, but aren’t real Unix, such as BeOS and Plan 9. Many embedded operating systems have a design based on Unix. The old Amiga computers have an OS based on an old relative of Unix.

Not Unix, but… Even Windows NT, 2000 and XP can be made partially compatible with Unix applications using Unix compatibility software called Cygwin. It isn’t Unix though, despite some POSIX compatibility.

There is a vast amount of software available for Unix, most of it completely free. Most of it will run on most if not all recent versions of Unix, from AIX on a mainframe to Linux on a pocket computer, to Mac OS X on an iMac. Learn to develop software for one type of Unix, and you can easily adapt to develop for another Unix. However, Unix is not a strict standard, in fact it can be difficult to define exactly what Unix actually is…

The Unix world There is a myth (from Microsoft, almost the only non-Unix OS company left) that Unix is dying out. Exactly the opposite is happening. Unix is everywhere. The “The Lord of The Rings” films were built using Unix. Unix dominates the Internet. Devices like Tivos contain Unix. The only area where Unix is weak is normal home or office ìdesktopî computing. This may change soon.

The most popular Unix OS now is probably Mac OS X! The Unix base of Mac OS X is hidden from users most of the time, but open up the Terminal application, and there is a nice csh shell and many BSD programs. If you hear people saying that Unix will never be suitable for desktop use by non-techie users, point them at a Mac.

Unix is far from perfect. It is very “mature”, and that brings almost as many problems as benefits. It is however changing and evolving very rapidly since the free Unixes appeared. The huge amount of work going into the free Unixes has revitalised Unix in general, but in the long run the success of of the free Unix OSs may soon kill the old commercial Unixes, particularly HP-UX and IRIX.

For a huge and detailed Unix family tree, follow this link:

Unix Family Tree

Yes, it’s confusing.