The Archlinux Wiki is my go-to for that kind of thing: https://wiki.archlinux.org/index.php/Systemd https://wiki.archlinux.org/index.php/Systemd Also, check t

The Archlinux Wiki is my go-to for that kind of thing: https://wiki.archlinux.org/index.php/Systemd https://wiki.archlinux.org/index.php/Systemd Also, check the related articles on the right sidebar on the top of the article. It doesn't document everything, but it quickly gets you to learning the overview, the basics, and what's most important for general usage of systemd. If you really want absolutely everything the references are the man-pages. Excluding those that document C functions, there seems to be 256 systemd man-pages in total. 36 are regular commands (section 1; like systemctl), 64 are file formats (section 5; like systemd.service), 139 are system administration commands (section 8; like daemons like systemd-networkd), and 17 are miscellaneous topics (section 7; like bootup). I would consider the manpages of section 1 and 5 to be the important ones, and just section 1 is enough if you never intend to read or write a service or other unit file yourself. Here's an online index of the manpages: https://www.freedesktop.org/software/systemd/man/index.html https://www.freedesktop.org/software/systemd/man/index.html