What breakage does this actually fix?

> (or something, I don't really understand systemd).

Remember how it was common in Gnome 2-land to have a session manager process? So you could go into there and say 'I want FOO started when I log in'?. People would use it for all sorts of fun things. Starting up browsers, launching their terminals, blocking daemons they didn't want launched.

Then along came XDG and the various *.desktop things to make app menus cross-platform. So you could put *.desktop files in ~/.config/autostart/ and have them autostart when you logged into X (provided you used a desktop environment that was compliant).

Systemd wants to do that same sort of thing for your user, but have it be system-wide. That is one of the reasons they want Kdbus.. so you wouldn't have to run all the dbus-launch stuff for each login. You could have a dbus for a user account and have it 'just work'. Thus you have 'user sessions'.

So a lot of the commands you use for managing the init system for your system can be used to manage your user session for your user by using the '--user' option.

So for example I have a ~/.config/systemd/user/synergys.service on my desktop. When I start up my laptop I have a corresponding synergyc service that launches and they try to talk over a ssh session. I can automate the management of all of this through systemd and '--user'.

systemctl enable --user synergys

systemctl start --user synergys

systemctl status --user synergys

journalctl --user -f

etc etc. These things work as expected, but just for your user account.

Thanks for highlighting that. The freedesktop bug is really illuminating, and I wish that people would read it, in full, and understand it before they fly off the handle blaming 'GNOME'... sigh!