Web: https://systemd.io/
Src: https://github.com/systemd/systemd
Systemd manpage index: https://www.freedesktop.org/software/systemd/man/
https://www.freedesktop.org/software/systemd/man/systemd.htm... :
man 1 systemd
man systemd
man init
...: man systemctl
man journalctl
man systemd.timer
man systemd-resolved
The Arch Linux wiki docs for systemd are succinct:
https://wiki.archlinux.org/title/systemdFedora docs > "Understanding and administering systemd" https://docs.fedoraproject.org/en-US/quick-docs/understandin...
RHEL7 System Administrator’s Guide > "Chapter 10. Managing Services with SystemD" https://access.redhat.com/documentation/en-us/red_hat_enterp...
I think systemd.directives(7) is an often overlooked manpage.
To get the big picture I read the systemd posts on https://0pointer.net/blog/archives.html But that's 10 years already! No idea what would be recommended today.
These sorta landmines when trying to just research/digest a concept can really suck. OP's tool really eloquently breaks things down to _just_ core concepts so you can quickly start to grok what I consider to be a relatively complex tool.
Overall I use the Arch wiki very often and it's because of the exact point you're making - I'm just being pedantic saying those slight distro differences can be a pain.
Lots of folks learn by example and hands-on labs. Personally, I'd much rather learn the basic ropes by jumping into a tool like OP's vs. finding/digging through all of these resources. I'll also criticize to say you likely already know much about systemd, and were able to pull/filter these resources much easier vs someone completely new to the concepts.
To illustrate further: vim is another tool that has outstanding learning resources, everything from very quick "hey get started" examples docs all the way up to adventure games. If I had to go back and relearn vim I would absolutely do it this way vs. digging on man pages like when I was a kid in the 90's. Personally, I learn by doing.
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Overall - OP's thingy is what I would call a "rich interactive learning tool." It's anecdotal, and obvious projection - but _for me_, interactive learning tools optimize the time it takes to fully "grok" a subject from scratch vs. jumping into a bunch of docs/man pages.
~Examples as Integration Tests as executable notebooks with output and state assertions may incur less technical debt.
How to manage containers with [MicroShift] k8s/k3d with systemd might be a good example.
Systemd man pages source: https://github.com/systemd/systemd/tree/main/man
Also https://www.freedesktop.org/software/systemd/man/systemd.mou... https://github.com/systemd/systemd/blob/main/man/systemd-mou... :
man systemd.mountThe docs are not friendly enough to introduce you to new tools, and they're mostly shallow enough to not explain the technical details of how things interact or where all the defaults are stored. They exist but clearly this page exists because they need to improve.
I know, I know, pull requests welcome....