What's the big difference between Linux and Unix??

Matthew Seaman m.seaman at infracaninophile.co.uk
Sat Jun 12 06:08:27 PDT 2004

On Sat, Jun 12, 2004 at 10:06:49AM +0200, Grauwmans Steven wrote:
> Linux is UNIX, but why is Fedora Core a Linux and FreeBSD a UNIX?
> I searched on the internet for an answer, but after visiting 10 sites I
> gave up.
> If U could please help me, I'm getting confused.

Because FreeBSD code is derived from the 4.4 BSD release by the CSRG
at Berkeley, and they developed their code based on Unix code from
AT&T who were the original authors of Unix.  

Linux on the otherhand was a cleanroom implementation of a unix-like
operating system not incorporating any code from previous Unix
systems.  (Despite what SCO is claiming, which IMHO is a load of

Mind you, there has been significant cross fertilization between
Linux, the BSD and SysV Unix camps.  I tend to think that Linux passes
the duck test as far as being a Unix variant, and that it should be
known as such.  I also think that the unix vs Unix(TM) distinction --
i.e. whether the OS has licensed code from AT&T or it's heirs -- is
pretty much irrelevant nowadays.

For more detail that you could possibly want about the descent of
Unix, see:


(Very much up-to-date, that site -- already mentions FreeBSD 4.10.)



Dr Matthew J Seaman MA, D.Phil.                       26 The Paddocks
                                                      Savill Way
PGP: http://www.infracaninophile.co.uk/pgpkey         Marlow
Tel: +44 1628 476614                                  Bucks., SL7 1TH UK
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