How to get grub-reboot working™
So while testing Proxmox VE 3.0 RC1 I had the need to reboot the system into a kernel version different than the one being the default in the bootloader GRUB. “lilo -R …” worked fine in the past, but with GRUB it’s not as trivial on the first sight to get its equivalent. I remembered to have had problems with grub-reboot in the past already, or to quote a friend of mine: “has grub-reboot worked ever?”
Well yes, grub-reboot works – but only once you’re aware of the fact that you need to manually edit /etc/default/grub. :( It’s actually documented at wiki.debian.org/GrubReboot, but not in the man page/info document of grub-reboot itself (great idea to provide a separate wiki page for this issue but not consider editing the official documentation instead, not).
So here you go:
# grep GRUB_DEFAULT /etc/default/grub
GRUB_DEFAULT=0
# sed -i 's/^GRUB_DEFAULT.*/GRUB_DEFAULT=saved/' /etc/default/grub
# grep GRUB_DEFAULT /etc/default/grub
GRUB_DEFAULT=saved
# update-grub
[...]
# grep '^menuentry' /boot/grub/grub.cfg
menuentry 'Debian GNU/Linux, with Linux 3.2.0-4-amd64' --class debian --class gnu-linux --class gnu --class os {
menuentry 'Debian GNU/Linux, with Linux 3.2.0-4-amd64 (recovery mode)' --class debian --class gnu-linux --class gnu --class os {
menuentry 'Debian GNU/Linux, with Linux 2.6.32-20-pve' --class debian --class gnu-linux --class gnu --class os {
menuentry 'Debian GNU/Linux, with Linux 2.6.32-20-pve (recovery mode)' --class debian --class gnu-linux --class gnu --class os {
menuentry 'Debian GNU/Linux, with Linux 2.6.32-5-amd64' --class debian --class gnu-linux --class gnu --class os {
menuentry 'Debian GNU/Linux, with Linux 2.6.32-5-amd64 (recovery mode)' --class debian --class gnu-linux --class gnu --class os {
# grub-reboot 2 # to boot the third entry, the command writes to /boot/grub/grubenv
# reboot
FTR: Filed as #707695.