I didn’t like this piece of advice myself back when I got it, but it was worth it: Start with introductory physical unix handbooks that cover user permissions,

I didn’t like this piece of advice myself back when I got it, but it was worth it: Start with introductory physical unix handbooks that cover user permissions, fork(2), and exec(2). Oddly enough containers only add something like a git-fs-chroot and network-chroot on top. The principles are all still the same. Like I said, I didn’t like this answer either until I read a few of the books.