systemd-debug-generator — Generator for enabling a runtime debug shell and masking specific units at boot
/usr/lib/systemd/system-generators/systemd-debug-generator
systemd-debug-generator is a generator
that reads the kernel command line and understands three
options:
If the systemd.mask= or rd.systemd.mask=
option is specified and followed by a unit name, this unit is
masked for the runtime (i.e. for this session — from boot to shutdown), similarly to the effect of
systemctl(1)'s
mask command. This is useful to boot with
certain units removed from the initial boot transaction for
debugging system startup. May be specified more than once.
rd.systemd.mask= is honored only by initial
RAM disk (initrd) while systemd.mask= is
honored only in the main system.
If the systemd.wants= or
rd.systemd.wants= option is specified
and followed by a unit name, a start job for this unit is added to
the initial transaction. This is useful to start one or more
additional units at boot. May be specified more than once.
rd.systemd.wants= is honored only by initial
RAM disk (initrd) while systemd.wants= is
honored only in the main system.
If the systemd.debug_shell or rd.systemd.debug_shell option is
specified, the debug shell service "debug-shell.service" is pulled into the boot
transaction and a debug shell will be spawned during early boot. By default,
/dev/tty9 is used, but a specific tty can also be specified, either with or without
the /dev/ prefix. To set the tty to use without enabling the debug shell, the
systemd.default_debug_tty= option can be used which also takes a tty with or without the
/dev/ prefix. Note that the shell may also be turned on persistently by enabling it
with systemctl(1)'s
enable command. rd.systemd.debug_shell is honored only by initial
RAM disk (initrd) while systemd.debug_shell is honored only in the main system.
systemd-debug-generator implements
systemd.generator(7).
systemd.extra-unit.*¶Credentials prefixed with "systemd.extra-unit." specify additional
units to add to the final system. Note that these additional units are added to both the initrd and
the final system. ConditionPathExists=!/etc/initrd-release can be used to make
sure the unit is conditioned out in the initrd. Note that this can also be used to mask units, by
simply specifying an empty value.
systemd.unit-dropin.*¶Credentials prefixed with "systemd.unit-dropin." add drop-ins for
the corresponding units in the final system. Each credential must be suffixed with the full unit name
including the unit extension. Its contents must be a valid unit drop-in file. Optionally, the unit
name may be followed with "~", followed by the drop-in name without the
".conf" suffix. If not specified, the name of the generated drop-in will be
"50-credential.conf". Note that these additional drop-ins are added to both the
initrd and the final system.