Debian Handbook for Debian 10 Buster
In terms of linux documentation, generally, I have two recommendations. One, install Arch Linux in a VM and mess around with it a bit. Not because I particularly like it, or use it for any production purposes. But because the Arch wiki is such a wealth of information on individual daemons and subsystems.Secondly, make use of the Arch wiki. By knowing at least the basics of how Arch is organized, you can better discern what technical reference material is unique to specific quirks of arch, and what is general to the same daemons running on debian or centos (postfix or dovecot, for instance).examples of generically useful reference:https://wiki.archlinux.org/index.php/Network_Time_Protocol_d...https://wiki.archlinux.org/index.php/Postfixhttps://wiki.archlinux.org/index.php/Systemd