From Rosetta Code

UNIX (all caps) is the trademark name of Unix, but the name was intended to be "normally" capitalized (Unix) by its creators. From wp:Unix#Branding:

"Unix" was the original formatting, but the usage of "UNIX" remains widespread because, according to Dennis Ritchie, when presenting the original Unix paper to the third Operating Systems Symposium of the American Association for Computing Machinery, "we had a new typesetter and troff had just been invented and we were intoxicated by being able to produce small caps." Many of the operating system's predecessors and contemporaries used all-uppercase lettering, so many people wrote the name in upper case due to force of habit.

So... I think that perhaps this article should be renamed to Unix, with UNIX redirecting appropriately (the opposite of how things currently are, and the way things are at Wikipedia). -- Eriksiers 20:29, 8 October 2009 (UTC)

Done. --Mwn3d 20:30, 8 October 2009 (UTC)
That was fast. I would've done it myself, but I was thinking about getting input from others first... oh, well. Thanks.
FWIW, the Jargon File's Unix entry (which is partially quoted in the above cite) ends with this: So, while the trademark today is 'UNIX', both capitalizations are grounded in ancient usage; the Jargon File uses 'Unix' in deference to dmr's wishes. -- Eriksiers 20:38, 8 October 2009 (UTC)