Is "unix" supposed to be "unix", "Unix", or "UNIX"?

The closest question I've seen is Expansion of the word UNIX. I also found this page that says it is only capitalized at the beginning of a sentence, however the Wikipedia page uses "Unix".

  • 1
    It seems as if you didn't read the articles you linked.
    – jesse_b
    Jul 26 '19 at 15:44
  • @Jesse_b I did read them, which is why I asked the question. I couldn't find a good authoritative source on this ("Green Parties world wide" doesn't strike me as the authority), and it doesn't seem to be used consistently by people. Jul 26 '19 at 15:48
  • Well to be fair people don't consistently use almost any form of grammar, but in this case I think it ultimately doesn't matter, people will know what you mean by either form however the fact that the trademark is UNIX seems pretty authoritative to me.
    – jesse_b
    Jul 26 '19 at 15:51
  • 1
    UNIX is a trade mark, so refers to the official Unix. Unix is a noun, and could refer to UNIX or other UNIX like systems: BSD, Gnu, etc. unix is wrong but acceptable (Depending on how much of a grammar nazi one is). Jul 26 '19 at 17:58
  • 1
    Because in English proper-nouns (names) are capitalised. So just the rules of English. (you may have noticed that I started this commend with a because, so also poor English. It just depends who is reading, and if they will judge you.) Jul 26 '19 at 18:15

From the wikipedia article you linked:

trademarked as UNIX

Also see:
http://tmsearch.uspto.gov/bin/showfield?f=doc&state=4808:1yqnd4.2.2 http://www.unix.org/trademark.html http://pubs.opengroup.org/onlinepubs/9699919799/frontmatter/trademarks.html

Also from the other article you linked:

The Bell Labs documentation was very careful to always spell UNIX in all capital letters, and small caps whereever possible.


This is a generic name for all UNIX-like operating systems, including Linux. The last patent on unix expired in Septmber 1989, and it became legal to freely distribute a unix that was not derived from UNIX. On that date, unix (the conceptual design and its associated technological cullture) ceased to be the intellectual property of whatever corporation owned the UNIX code base, and became part of the human cultural heritage.

  • So if I were to say to you "For this job, you need to know some basic unix commands," that should be lower case? Is there an authoritative source on this? (the one I linked to is from some green parties website..) Jul 26 '19 at 15:45
  • It depends on if you are referring to UNIX or UNIX-like commands. However ultimately it doesn't matter, nobody will question it and everyone will understand what you mean.
    – jesse_b
    Jul 26 '19 at 15:46
  • 2
    @Scribble If I were told that, I'd ask "Which Unix?" Be specific about your platforms
    – muru
    Jul 26 '19 at 15:48
  • Linux is not a Unix. It is a kernel. It is used in Android (not a Unix), Gnu/Linux (a Unix), and other places. Jul 26 '19 at 17:59

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