I'd like to say that the mechanisms described from the perspective of the language where they've been implemented into. Lincoln D. Stein does not do his best to describe the mechaisms , so one can not really go in depth with this book. The APUE book however is much better suited for learning these kinds of things because it exposes one to exactly what system calls are made at each step , and goes as far as to implementing some of the functions which cannot be understood so easily just be reading the manpage or Stein's book. But I am biased , I don't like to treat things as black-boxes when , I want to really know what I'm doing so maybe other people want to read and apply things faster.