The unit files are located at path /usr/lib/systemd/system.
This fixes the path reference to the unit file by adding the missing
path component system.
symlink in the distribution package, rather than depending on <command>systemctl
enable</command> in the postinst scriptlets of your package. More specifically, for your
update script create a .service file, without [Install] section, and then add a symlink like
- <filename index="false">/usr/lib/systemd/system-update.target.wants/foobar.service</filename>
+ <filename index="false">/usr/lib/systemd/system/system-update.target.wants/foobar.service</filename>
→ <filename index="false">../foobar.service</filename> to your package.</para>
</listitem>