How can I choose which OS grub will reboot me into—before I reboot?

Question

LILO had a simple feature that allowed one to select the boot menu entry that should be used on the next reboot while in Linux, thus one could select the OS to be booted into on shutdown and didn't had to wait till the computer rebooted to the boot menu and select the next entry manually.

For Grub that feature has existed as unofficial patch as well.

This was quite some years ago. Has that feature made it into mainline Grub in the meantime? Is it available under Ubuntu and is there any way to integrate it with the GUI (i.e. have not only a "Reboot" entry, but a "Reboot into Windows" entry in the shutdown menu)?

Answer 1

There is a grub command just to do so, it is grub-reboot.

It seems to only work when you have grub configured to start with the last saved entry. So if you have not already done so, modify /etc/default/grub and set

GRUB_DEFAULT=saved

then update grub configuration file:

sudo update-grub

From now on, at each boot grub will start the last used entry.

Now, if you want to set in advance what should be the system to boot the next time, use

sudo grub-reboot ENTRY

where ENTRY could be a number relative to a menu entry (numbered starting from 0), or an exact menu entry title, for example

sudo grub-reboot "Microsoft Windows XP Professional (on /dev/sda1)"

This command can easily be make available as a launcher

#!/usr/bin/env xdg-open
#
# save as ~/Desktop/reboot-into-windows.desktop
#

[Desktop Entry]
Version=1.0
Type=Application
Terminal=false
Exec=sh -c 'gksu "grub-reboot 2" && gnome-session-save --shutdown-dialog'
Name=Reboot into Windows
Icon=gnome-panel-launcher

but I don't know how it could be integrated into the system menu.

You can obtain the available menu entry title with

sed -n '/menuentry/s/.*\(["'\''].*["'\'']\).*/\1/p' /boot/grub/grub.cfg 

Answer 2

As far as I understood this will not be exactly what you want but I guess pretty close. Just follow the link webupdate article.

Answer 3

I'm not sure if this will 100% also work in ubuntu, but I once made this work on a centos machine

basically you'll have to tell grub which id # from grub.conf it should run next. The id # can be found out by

echo `sudo grep ^title /boot/grub/grub.conf | grep -n Windows | cut -f 1 -d:`-1

so in my case this would e.g. output "4-1" as the fourth entry in my grub.conf contains the text "Windows". (Replace this with the actual entry name (also partially) you want to use. Then you can feed this to grub like:

echo "savedefault --stage2=/boot/grub/stage2 --default=4-1 --once" | sudo /sbin/grub

and at the next reboot it should automatically boot the entry you've told it to.

this all can be put together in a script like the following:

#!/bin/sh
let NEWBOOT=`sudo grep ^title /boot/grub/grub.conf | grep -n Windows | cut -f 1 -d:`-1
echo Booting $NEWBOOT - `sudo grep ^title.\*Windows /boot/grub/grub.conf`
echo "savedefault --stage2=/boot/grub/stage2 --default=$NEWBOOT --once" | sudo /sbin/grub
sudo reboot

the script will automatically determine which entry from your grub.conf corresponds to the text "Windows", will feed this to grub to tell what should be loaded on next boot and will reboot your pc.

for a gui you could e.g. add a shortcut icon to your desktop to achive this.

Answer 4

Simply edit /boot/grub/grub.cfg and change the default entry to point to the entry you want to boot. The value can either be the ordinal number of the entry (starting from zero for the first one) or you can place the full title of the entry you want in quotes.