For those looking for a broader/more portable introduction, Xavier Leroy and Didier Rémy wrote a great high-level text on UNIX system programming a long time ago [1]. Of course it uses ocaml (perhaps motivating some to learn that language) but the style is low-level and straightforwardly imperative. The advantage is that it sweeps up a lot of the messy and boring error handling into the ocaml runtime and/or exceptions. This makes the code a lot easier to follow, but of course makes it look misleadingly simpler than it would be in C (etc).
Thanks! I just started the OCaml Programming Book this week to learn and language and get better at functional programming.
Cant wait to jump into this after
[1] https://ocaml.github.io/ocamlunix/
https://www.informit.com/store/linux-application-development...