updates on the console during bootup. With error, only messages about failures are shown, but boot is otherwise quiet.  auto behaves like false until there is a significant delay in boot. Defaults to enabled,
           unless quiet is passed as kernel command line option, in which case it defaults to error. If specified overrides the system manager configuration file option ShowStatus=, see systemd‐system.conf(5).

       systemd.status_unit_format=
           Takes name, description or combined as the value. If name, the system manager will use unit names in status messages. If combined, the system manager will use unit names and description in status messages. When
           specified, overrides the system manager configuration file option StatusUnitFormat=, see systemd‐system.conf(5).

       systemd.log_color, systemd.log_level=, systemd.log_location, systemd.log_target=, systemd.log_time, systemd.log_tid
           Controls log output, with the same effect as the $SYSTEMD_LOG_COLOR, $SYSTEMD_LOG_LEVEL, $SYSTEMD_LOG_LOCATION, $SYSTEMD_LOG_TARGET, $SYSTEMD_LOG_TIME, and $SYSTEMD_LOG_TID environment variables described above.
           systemd.log_color, systemd.log_location, systemd.log_time, and systemd.log_tid= can be specified without an argument, with the same effect as a positive boolean.

       systemd.default_standard_output=, systemd.default_standard_error=
           Controls default standard output and error output for services and sockets. That is, controls the default for StandardOutput= and StandardError= (see systemd.exec(5) for details). Takes one of inherit, null, tty,
           journal, journal+console, kmsg, kmsg+console. If the argument is omitted systemd.default-standard-output= defaults to journal and systemd.default-standard-error= to inherit.

       systemd.setenv=
           Takes a string argument in the form VARIABLE=VALUE. May be used to set default environment variables to add to forked child processes. May be used more than once to set multiple variables.

       systemd.machine_id=
           Takes a 32 character hex value to be used for setting the machine-id. Intended mostly for network booting where the same machine-id is desired for every boot.

       systemd.set_credential=
           Sets a system credential, which can then be propagated to system services using the LoadCredential= setting, see systemd.exec(5) for details. Takes a pair of credential name and value, separated by a colon. Note
           that the kernel command line is typically accessible by unprivileged programs in /proc/cmdline. Thus, this mechanism is not suitable for transferring sensitive data. Use it only for data that is not sensitive
           (e.g. public keys/certificates, rather than private keys), or in testing/debugging environments.

           For further information see System and Service Credentials[8] documentation.

       systemd.import_credentials=
           Takes a boolean argument. If false disables importing credentials from the kernel command line, the DMI/SMBIOS OEM string table, the qemu_fw_cfg subsystem or the EFI kernel stub.

       quiet
           Turn off status output at boot, much like systemd.show_status=no would. Note that this option is also read by the kernel itself and disables kernel log output. Passing this option hence turns off the usual output
           from both the system manager and the kernel.

       debug
           Turn on debugging output. This is equivalent to systemd.log_level=debug. Note that this option is also read by the kernel itself and enables kernel debug output. Passing this option hence turns on the debug output
           from both the system manager and the kernel.

       emergency, rd.emergency, -b
           Boot into emergency mode. This is equivalent to systemd.unit=emergency.target or rd.systemd.unit=emergency.target, respectively, and provided for compatibility reasons and to be easier to type.

       rescue, rd.rescue, single, s, S, 1