without actually executing
           any of the determined jobs. This option is useful for debugging
           only. Note that during regular service manager start-up additional
           units not shown by this operation may be started, because hardware,
           socket, bus or other kinds of activation might add additional jobs
           as the transaction is executed. Use --system to request the initial
           transaction of the system service manager (this is also the implied
           default), combine with --user to request the initial transaction of
           the per-user service manager instead.

       --system, --user
           When used in conjunction with --test, selects whether to calculate
           the initial transaction for the system instance or for a per-user
           instance. These options have no effect when invoked without --test,
           as during regular (i.e. non---test) invocations the service manager
           will automatically detect whether it shall operate in system or
           per-user mode, by checking whether the PID it is run as is 1 or not.
           Note that it is not supported booting and maintaining a system with
           the service manager running in --system mode but with a PID other
           than 1.

       -h, --help
           Print a short help text and exit.

       --version
           Print a short version string and exit.

   Options that duplicate kernel command line settings
       Those options correspond directly to options listed above in "Kernel
       Command Line". Both forms may be used equivalently for the system
       manager, but it is recommended to use the forms listed above in this
       context, because they are properly namespaced. When an option is
       specified both on the kernel command line and as a normal command line
       argument, the latter has higher precedence.

       When systemd is used as a user manager, the kernel command line is
       ignored and only the options described below are understood.
       Nevertheless, systemd is usually started in this mode through the
       user@.service(5) service, which is shared between all users. It may be
       more convenient to use configuration files to modify settings (see
       systemd‐user.conf(5)), or environment variables. See the "Environment"
       section above for a discussion of how the environment block is set.

       --unit=
           Set default unit to activate on startup. If not specified, defaults
           to default.target. See systemd.unit= above.

       --dump-core
           Enable core dumping on crash. This switch has no effect when running
           as user instance. Same as systemd.dump_core= above.

       --crash-vt=VT
           Switch to a specific virtual console (VT) on crash. This switch has
           no effect when running as user instance. Same as systemd.crash_chvt=
           above (but not the different spelling!).

       --crash-shell
           Run a shell on crash. This switch has no effect when running as user
           instance. See systemd.crash_shell= above.

       --crash-reboot
           Automatically reboot the system on crash. This switch has no effect
           when running as user instance. See systemd.crash_reboot above.

       --confirm-spawn
           Ask for confirmation when spawning processes. This switch has no
           effect when run as user instance.