Maintainer of ziglearn.org here. I have just now added details on using stat and directory creation + walking here:

https://ziglearn.org/chapter-2/#filesystem

And details on reading the next line here:

https://ziglearn.org/chapter-2/#readers-and-writers

fread/fstat/fgets/fopen is now all covered. The build system is something I need to cover much more thoroughly, but is something that will take a long time.