This simple design is what intrigued me, and most people, about Unix (well, at least us geeks). Pretty much everything you do in Unix is done with only six basic operations (system calls)…
And you can build up pretty much everything from those six basic system calls. -- Linus Torvalds, Just For Fun, Book, 2002.
{ FYI, [hey are fork, exec, open, close, read, write}