It seems that the Linux kernel (All POSIX OSs?) contains only 300+ system calls. Does this mean that any OS implementing those APIs (directly or by translation tables) can run software written for Linux (e.g. Firefox)?
If not - what is needed besides that?
Yes, this is a very basic question on a topic I'm only starting out with (OS design). Apparently it's not accepted on StackOverflow, and I was directed here instead. If it's not - please let me know. (And if so, if you know where it does belong, I'll be happy to hear.)