grub-reboot

set default boot entry for next reboot only

TLDR

Set the default boot entry for the next boot only

$ sudo grub-reboot [entry_number]

Set default for an alternative boot directory for next boot

$ sudo grub-reboot --boot-directory=/[path/to/boot_directory] [entry_number]

Set default for a submenu entry (use > to separate submenu and entry titles)

$ sudo grub-reboot "[submenu_title]>[entry_title]"

grub-reboot sets the default boot entry for the next boot only. After booting once, GRUB reverts to the permanent default set by grub-set-default or the configuration file.The entry can be specified as a number (0 for first entry), the full entry name from grub.cfg, or a menu entry identifier. For entries within submenus, use the greater-than character (>) to separate the submenu title and the entry title, with no extra spaces (e.g., "Advanced options>Ubuntu, with Linux 5.15"). Use grep menuentry /boot/grub/grub.cfg to see available entries.This is useful for one-time boots into recovery mode, alternative kernels, or other operating systems without permanently changing the boot order.

PARAMETERS

entry

Menu entry number (0-indexed), full entry name, or identifier.

--boot-directory=DIR

Find GRUB images under DIR/grub instead of the default /boot/grub.

-h, --help

Print help message and exit.

-V, --version

Print version information and exit.

-v, --verbose

Print verbose messages.

CONFIGURATION

/etc/default/grub

Must contain GRUB_DEFAULT=saved for grub-reboot to function.

CAVEATS

Requires GRUB_DEFAULT=saved in /etc/default/grub and a subsequent grub-mkconfig run to function. The setting is stored in grubenv, which must be writable. Only affects the immediate next boot. When GRUB cannot write to the environment block (e.g., on MDRAID or LVM), the chosen entry may remain the default even after reboot.

HISTORY

grub-reboot is part of GRUB 2, providing the "boot once" functionality that was present in GRUB Legacy. It enables safe testing of alternative boot configurations with automatic fallback.