[systemd-devel] It is impossible to distinguish between services that never run or were skipped

[Andrey Borzenkov]

Consider

{pts/1}% systemctl status plymouth-start.service
plymouth-start.service - Show Plymouth Boot Screen
          Loaded: loaded (/lib/systemd/system/plymouth-start.service)
          Active: inactive (dead)
          CGroup: name=systemd:/system/plymouth-start.service
{pts/1}% systemctl status plymouth-quit.service
plymouth-quit.service - Terminate Plymouth Boot Screen
          Loaded: loaded (/lib/systemd/system/plymouth-quit.service)
          Active: inactive (dead)
          CGroup: name=systemd:/system/plymouth-quit.service

The former did run on boot, but actual execution was skipped due to
/dev/.systemd/plymouth.
The latter was never run because in run level 5 we do not stop
plymouth and rely on prefdm to either hand over screen or stop it.

How do you tell the difference?