Isn't Linux just UNIX under a different name?

By David M Williams
Thursday, 21 August 2008 13:12

Opinion and Analysis

What's the big deal about Linux? Isn't it at heart just a PC-based version of UNIX – the ‘70’s hit operating system which has outlived the predictions of its demise throughout the ‘90’s? If you’ve come from a Solaris or HP/UX or AIX background isn’t a PC-based UNIX a bit, well, passé?


To answer this you need to know the history. UNIX was kicked off by Kenneth Thompson and Dennis Ritchie around the time man first landed on the moon.

They’d been working on a project called MULTICS which was aborted. With a bit of time to kill the duo decided to write a space war game running on a PDP computer sitting around. Demonstrating the thinking that defines either brilliance or madness they first thought they ought to write an operating system before they could produce the game. This was the birth of UNIX.

AT&T took over the rights to UNIX, but program code was released to educational institutions for their own use. This caused the evolution of UNIX in two different directions as it was built upon in the laboratories of universities and large enterprises. AT&T’s evolution became known as System V while Berkeley University in California produced their Berkeley UNIX variation called BSD.

Major UNIX vendors followed one branch or the other or, even both as in the case of Sun Microsystems whose SunOS operating system was a Berkeley derivative but switched to System V when they rebranded SunOS as Solaris.

Ownership changed hands as time went on; Novell, SCO and Caldera all got into the fray. You may recall SCO filed lawsuits asserting their ownership of UNIX and alleging an effective copyright over competing products which they claimed used “original source code” from the proprietary UNIX product.

Linux, on the other hand, came about not through a space game or the interests of corporations. In 1991 Linus Torvalds began writing a kernel on his home Intel-based computer which he named Linux. The kernel is really the only item that is truly known as “Linux” despite the many discs of distributions like Ubuntu and Fedora which are mostly referred to under this name.

The kernel is the essential core of an operating system which provides all the interaction between computer programs and the underlying hardware as well as scheduling many programs to apparently run at the same time. Torvalds built his own without either support from a large organisation or the benefit of seeing existing source code (despite the SCO claims.)

Of course, Torvalds did have the advantage of being able to base his work on how an established and capable multi-user operating system performed and it would be wrong to suggest Linux came about totally in isolation to UNIX; there’s no doubt it was inspired by UNIX as well as MINIX – which itself was a UNIX-based operating system by Andrew Tanenbaum.

MINIX is aimed at minimal PC-based hardware platforms and originally began as a teaching tool; the latest version – MINIX 3 – adds the goal of reliable application performance on embedded computers or resource-limited systems in production and real world usage.

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