| SYSTEMD-DEBUG-GENERATOR(8) | systemd-debug-generator | SYSTEMD-DEBUG-GENERATOR(8) |
.SH "NAME" systemd-debug-generator - Generator for enabling a
runtime debug shell and masking specific units at boot
.SH "SYNOPSIS"
.PP /usr/lib/systemd/system-generators/systemd-debug-generator
.SH "DESCRIPTION"
.PP systemd-debug-generator is a generator that provides some
debugging functionality.
.PP systemd-debug-generator implements
systemd.generator(7).
.SH "KERNEL COMMAND LINE"
.PP systemd-debug-generator understands the following kernel command
line parameters:
.PP systemd.mask=, rd.systemd.mask=
These options take a unit name as argument. The unit specified 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.
The option prefixed with rd. is honored only in the initrd, while the one
without prefix is only honored on the host.
Added in version 215.
.RE
.PP systemd.wants=, rd.systemd.wants=
These options take a unit name as argument. 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. The option
prefixed with rd. is honored only in the initrd, while the one that is not
prefixed only on the host.
Added in version 215.
.RE
.PP systemd.debug_shell, rd.systemd.debug_shell,
systemd.default_debug_tty=, rd.systemd.default_debug_tty=
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. The options prefixed with rd. are honored only in the
initrd, while the ones without prefix are only honored on the host.
Added in version 215.
.RE
.PP systemd.break=, rd.systemd.break=
Takes one of pre-udev, pre-basic, pre-mount, or
pre-switch-root (the default for the rd. option). It also accepts
multiple values separated by comma (,). These options allow one to pause the
boot process at a certain point and spawn a debug shell. After exiting this
shell, the system will resume booting. The option prefixed with rd. is
honored only in the initrd, while the one without prefix is only honored on
the host.
.sp
Table 1. Available breakpoints
| Breakpoints | Description | Can be used in the initrd | Can be used on the host |
| pre-udev | Before starting to process kernel uevents, i.e., before systemd-udevd.service starts. | ✓ | ✓ |
| pre-basic | Before leaving early boot and regular services start, i.e., before basic.target is reached. | ✓ | ✓ |
| pre-mount | Before the root filesystem is mounted, i.e., before sysroot.mount starts. | ✓ | ✗ |
| pre-switch-root | Before switching from the initrd to the real root. | ✓ | ✗ |
Added in version 258.
.RE
.SH "SYSTEM CREDENTIALS"
.PP 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.
Added in version 256.
.RE
.PP 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.
Added in version 256.
.RE
.SH "SEE ALSO"
.PP systemd(1), systemctl(1), kernel-command-line(7),
systemd.system-credentials(7), bootup(7)
| systemd 262.2 |