[rca]

Well you're right, not everything is a file. We can't treat a socket like a file because the networks is less reliable/fast/whatever than the file system. You can't treat a pipe just like a file because it needs to have someone reading it if you want to write to it, and there are special files accepting weird ioctls because they have weird capabilities that need to be exploited, etc. But still, all these do have things in common, mainly they can be read from and written to, and the 'file' is an abstraction that represent just that. To me this is very much like an object oriented concept. This is polymorphism applied to os resources. If several resources have part of their interfaces in common, then exposing it as a higher level abstraction can help simplify programs that then don't have to worry about type specific details if they don't need to. Anyway even if nothing really is a file, I often find it useful to think about everything as one, as long as I don't forget it's actually not when the abstraction stops being valid. And I'd guess it also helps design and implement the system itself.