With many of those service like Avahi and ModemManager, you may simply not need them because they don't run what you may use on the system. You can disable any or all of them with systemctl (as root), e.g.:
Code:
systemctl disable ModemManager
and they won't start up on next boot. If you want to stop them immediately you can run:
Code:
systemctl stop ModemManager
The simplest idea is find out what they do, decide whether you want that service, or use it, then enable and disable accordingly. If you disable lots of them, if not all, and then have trouble, you can simply re-enable them with the option: 'enable' replacing the term 'disable' in the above commands and start them up again immediately using the the option 'start' replacing 'stop' in the above command. If for example, you are running NetworkManager, then the network service shouldn't be run because the system only responds well to one networking set of programs, so, if you run network, then NetworkManager should be disabled. You can find out much of the running stuff by looking into files and directories under /etc/systemd/system/ to see what's there. There are other programs that run apart from what's there, and to find those you can use the systemctl command:
Code:
systemctl list-unit-files
which shows what's there and the status, such as active or disabled.
