kernel-command-line(7)

NAME#

kernel-command-line - Kernel command line parameters

SYNOPSIS#

/proc/cmdline

DESCRIPTION#

The kernel, the programs running in the initrd and in the host system may be configured at boot via kernel command line arguments. In addition, various systemd tools look at the EFI variable "SystemdOptions" (if available). Both sources are combined, but the kernel command line has higher priority. Please note that the EFI variable is only used by systemd tools, and is ignored by the kernel and other user space tools, so it is not a replacement for the kernel command line.

For command line parameters understood by the kernel, please see kernel-parameters.html[1] and bootparam(7).

For command line parameters understood by the initrd, see the documentation of the specific initrd implementation of your installation.

CORE OS COMMAND LINE ARGUMENTS#

systemd.unit=, rd.systemd.unit=, systemd.dump_core, systemd.crash_chvt, systemd.crash_shell, systemd.crash_action=, systemd.confirm_spawn, systemd.service_watchdogs, systemd.show_status, systemd.status_unit_format=, systemd.log_target=, systemd.log_level=, systemd.log_location=, systemd.log_color, systemd.log_ratelimit_kmsg, systemd.default_standard_output=, systemd.default_standard_error=, systemd.setenv=, systemd.machine_id=, systemd.set_credential=, systemd.set_credential_binary=, systemd.import_credentials=, systemd.reload_limit_interval_sec=, systemd.reload_limit_burst=

Added in version 186.

systemd.mask=, systemd.wants=, systemd.debug_shell, systemd.default_debug_tty=

Added in version 215.

systemd.run=, systemd.run_success_action=, systemd.run_failure_action=

Added in version 240.

systemd.early_core_pattern=

Added in version 240.

systemd.restore_state=

Added in version 209.

systemd.ssh_auto=, systemd.ssh_listen=

Added in version 256.

systemd.volatile=

Added in version 233.

quiet

Added in version 186.

debug

Added in version 205.

-b, rd.emergency, emergency, rd.rescue, rescue, single, s, S, 1, 2, 3, 4, 5

Added in version 186.

locale.LANG=, locale.LANGUAGE=, locale.LC_CTYPE=, locale.LC_NUMERIC=, locale.LC_TIME=, locale.LC_COLLATE=, locale.LC_MONETARY=, locale.LC_MESSAGES=, locale.LC_PAPER=, locale.LC_NAME=, locale.LC_ADDRESS=, locale.LC_TELEPHONE=, locale.LC_MEASUREMENT=, locale.LC_IDENTIFICATION=

Added in version 186.

fsck.mode=, fsck.repair=

Added in version 186.

quotacheck.mode=

Added in version 186.

systemd.journald.forward_to_syslog=, systemd.journald.forward_to_kmsg=, systemd.journald.forward_to_console=, systemd.journald.forward_to_wall=

Added in version 186.

vconsole.keymap=, vconsole.keymap_toggle=, vconsole.font=, vconsole.font_map=, vconsole.font_unimap=

Added in version 186.

udev.log_level=, rd.udev.log_level=, udev.children_max=, rd.udev.children_max=, udev.exec_delay=, rd.udev.exec_delay=, udev.event_timeout=, rd.udev.event_timeout=, udev.timeout_signal=, rd.udev.timeout_signal=, udev.blockdev_read_only, rd.udev.blockdev_read_only, net.ifnames=, net.naming_scheme=

Added in version 186.

plymouth.enable=

Added in version 186.

luks=, rd.luks=, luks.crypttab=, rd.luks.crypttab=, luks.name=, rd.luks.name=, luks.uuid=, rd.luks.uuid=, luks.options=, rd.luks.options=, luks.key=, rd.luks.key=

Added in version 186.

fstab=, rd.fstab=

Added in version 186.

root=, rootfstype=, rootflags=, ro, rw

If root= is not set (or set to "gpt-auto") the automatic root partition discovery implemented by systemd-gpt-auto-generator(8) will be in effect. In this case, rootfstype=, rootflags=, ro, rw will be interpreted by systemd-gpt-auto-generator.

Added in version 215.

mount.usr=, mount.usrfstype=, mount.usrflags=

Added in version 235.

veritytab=, rd.veritytab=, roothash=, systemd.verity=, rd.systemd.verity=, systemd.verity_root_data=, systemd.verity_root_hash=, systemd.verity_root_options=, usrhash=, systemd.verity_usr_data=, systemd.verity_usr_hash=, systemd.verity_usr_options=

Added in version 233.

systemd.getty_auto=

Added in version 250.

systemd.gpt_auto=, rd.systemd.gpt_auto=

Added in version 215.

systemd.image_policy=

Added in version 254.

systemd.default_timeout_start_sec=

Added in version 230.

systemd.default_device_timeout_sec=

Added in version 254.

systemd.watchdog_device=

Added in version 236.

systemd.watchdog_sec=

Added in version 250.

systemd.watchdog_pre_sec=

Added in version 251.

systemd.watchdog_pretimeout_governor=

Added in version 251.

systemd.cpu_affinity=

Added in version 245.

modules_load=, rd.modules_load=

Added in version 187.

nameserver=, domain=

Added in version 253.

resume=, resumeflags=

Added in version 217.

resume_offset=

Added in version 254.

systemd.firstboot=

Added in version 233.

systemd.condition_needs_update=

Added in version 246.

systemd.condition_first_boot=

Added in version 246.

systemd.clock_usec=

Added in version 246.

systemd.random_seed=

Note that if this option is used the seed is accessible to unprivileged programs from /proc/cmdline. This option is hence a security risk when used outside of test systems, since the (possibly) only seed used for initialization of the kernel's entropy pool might be easily acquired by unprivileged programs.

It is recommended to pass 512 bytes of randomized data (as that matches the Linux kernel pool size), which may be generated with a command like the following:

dd if=/dev/urandom bs=512 count=1 status=none | base64 -w 0

Again: do not use this option outside of testing environments, it is a security risk elsewhere, as secret key material derived from the entropy pool can possibly be reconstructed by unprivileged programs.

Added in version 246.

systemd.allow_userspace_verity=

Added in version 256.

systemd.hostname=

Added in version 246.

systemd.tty.term.tty=, systemd.tty.rows.tty=, systemd.tty.columns.tty=

Added in version 254.

systemd.battery_check=

Added in version 254.

ifname=, net.ifname_policy=

Added in version 245.

systemd.tpm2_wait=

Added in version 256.

HISTORY#

systemd 252

Added in version 252.

SEE ALSO#

systemd(1), systemd-system.conf(5), bootparam(7), systemd.system-credentials(7), smbios-type-11(7), systemd-debug-generator(8), [email protected](8), systemd-quotacheck.service(8), systemd-journald.service(8), systemd-vconsole-setup.service(8), systemd-udevd.service(8), plymouth(8), systemd-cryptsetup-generator(8), systemd-veritysetup-generator(8), systemd-fstab-generator(8), systemd-getty-generator(8), systemd-gpt-auto-generator(8), systemd-volatile-root.service(8), systemd-modules-load.service(8), [email protected](8), systemd-rfkill.service(8), systemd-hibernate-resume-generator(8), systemd-firstboot.service(8), bootctl(1)

NOTES#

1.

kernel-parameters.html