This is not a blog post about how to write a shell, it doesn't explain how fork actually works, it doesn't actually make the program deterministic, and it takes

This is not a blog post about how to write a shell, it doesn't explain how fork actually works, it doesn't actually make the program deterministic, and it takes far too long to explain the concept of independent concurrent processsing. That's what's wrong. If you want a detailed explanation with examples you'd have to paste several chapters from a book on Unix programming in the comment thread, although in this case there's probably already a StackOverflow thread that summarizes the problems with this post's subject.