In theory, all questions on the unix-stackexchange could be tagged linux?
Isn't it then a bit redundant to have a linux tag? OR is it there to discriminate between linux or unix specific questions?
It does make sense for the reason Steven said -- to mark questions that are Linux-specific. Unfortunately, I think it's likely to get put on lots of questions that aren't actually Linux-specific, just like distro tags will get put on questions that aren't distro-specific. There are even 18 questions right now tagged with both [linux] and [unix], which is fairly ridiculous, but I think we'll just have to handle those cases manually (xeno has been pretty active at removing tags that shouldn't be on questions)