I have been reading up and investigating systemd and systemctl on Debian 8 Jessie.
When running
$ sudo systemctl list-units --all --type=service
a few services appear in the list that have no unit-file associated to them such as:
● clamav-daemon.service | not-found | inactive | dead | clamav-daemon.service ● console-screen.service | not-found | inactive | dead | console-screen.service ● festival.service | not-found | inactive | dead | festival.service ● greylist.service | not-found | inactive | dead | greylist.service ● keymap.service | not-found | inactive | dead | keymap.service ● krb5-kdc.service | not-found | inactive | dead | krb5-kdc.service
Yet at the same time, when running
$ sudo systemctl list-unit-files --all --type=service
there are no unit-files associated to the above units.
My question is:
How can systemctl list these services as units (or even know that these units exist), if there are no unit-files that exist for these units?