Without Unix, there would have been no Minix (Tanenbaum et al.) orGNU (Richard Stallman et al.).Without Minix, there would be no inspiration to write Linux. Remember that Linus started his “project” because he didn’t like many of the design decisions Tanenbaum has taken in Minix, including the microkernel. In fact, Linus has tried to submit some changes to the professor and the latter rejected them. So the young chap decided to write his own kernel using his design.Without GNU, there would be no open source tools that Linus himself used to write, compile, test and distribute his project, to become a few years later a global phenomenon. Also, the fact that GNU was already an established Unix clone (minus an operating kernel) at that time helped Linus to focus on the missing part, the kernel. Otherwise, he would not have known where to start.And finally, Unix was the template all of the above (and more) were trying to imitate. Without it, there would have been nothing to clone from.