I'm not sure if we still need both unix and linux. Unix is a broader family of operating systems and Linux is one of them under Unix. I don't think we should just have linux since there are questions about other Unix-like operating systems.
1\$\begingroup\$ Do we need Windows and OSX and Android and iOS tags? \$\endgroup\$– nhgrifJul 4, 2015 at 19:33
\$\begingroup\$ @nhgrif That is a good question. You should start a discussion on that here. \$\endgroup\$– user34073Jul 4, 2015 at 19:36
1\$\begingroup\$ @nhgrif Yes we do. \$\endgroup\$– Simon ForsbergJul 4, 2015 at 19:37
1\$\begingroup\$ Then Linux & Unix cannot be combined. Linux and Unix have about as much in common as Android & Linux or OS X & Unix. \$\endgroup\$– nhgrifJul 4, 2015 at 19:38
3\$\begingroup\$ When answering this question, we must keep in mind that OS X has almost the exact same relationship with Unix as does Linux, and that any attempt to synonymize the Unix family of operating systems should basically boil down into simply two tags: [windows-based-os] & [unix-based-os]. Are these tags specific enough or useful to the site? And if they were so similar, the SE site would just be called "Unix" rather than "Unix & Linux", and "Ask Different" probably wouldn't exist. \$\endgroup\$– nhgrifJul 4, 2015 at 19:47
Synonymizing these tags would be an absolutely wrong and harmful decision.
Let's look across the Stack Exchange network to see what sites like "Unix & Linux" or "Super User" say about Linux, Unix, and other operating systems:
Is Linux a Unix? Which is answered with "it depends", basically.
Is Mac OS X UNIX? Which is answered mostly with "yes".
Do we want to synonymize osx & unix? The users of "Unix & Linux" are more confident about the similarities of these two than they are of linux & unix.
There are other questions and answers on the topic regarding comparing various operating systems to each other and pointing out their similarities.
At the end of the day, unix may be a bit like an umbrella tag, under which you could put a handful of other operating system tags, like osx, linux, android, ios... but Linux and Unix are not exactly the same thing. Nor is OSX and Unix.
While things that work in Unix will tend to work in OS X or Linux, it's not necessarily true for the reverse.
2\$\begingroup\$ I agree that they should not be synonymized (sp?), and that UNIX is an effective "umbrella" tag for when the specifics are not as relevant. There are enough specialized items in Linux vs. general UNIX, that it makes sense, and these things are what make the different "flavours" important, and differentiate between BSD, cygwin, OSX, etc. The user should be able to choose with the relevant tag(s). \$\endgroup\$– rolflJul 4, 2015 at 19:56