Systemd：サービスの依存関係を探す

$ systemctl list-dependencies systemd-sysusers.service --all --reverse
systemd-sysusers.service
● └─sysinit.target
●   ├─accounts-daemon.service
●   │ └─graphical.target
●   ├─acpid.path
●   │ └─paths.target
●   │   └─basic.target
●   │     └─multi-user.target
●   │       └─graphical.target

man systemctl:

   list-dependencies [UNIT...]
       Shows units required and wanted by the specified units.
       This recursively lists units following the Requires=,
       Requisite=, ConsistsOf=, Wants=, BindsTo= dependencies. If
       no units are specified, default.target is implied.

       By default, only target units are recursively expanded.
       When --all is passed, all other units are recursively
       expanded as well.

       Options --reverse, --after, --before may be used to change
       what types of dependencies are shown.

       Note that this command only lists units currently loaded
       into memory by the service manager. In particular, this
       command is not suitable to get a comprehensive list at all
       reverse dependencies on a specific unit, as it won't list
       the dependencies declared by units currently not loaded.