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I have a dual boot Linux/windows system set up, and frequently switch from one to the other. I was thinking if I could add a menu item in one of the menus to reboot directly into windows, without stopping at the GRUB prompt.

I saw this question on a forum, that's exactly what I want but it's dealing with lilo, which is not my case.

I thought of a solution that would modify the default entry in the GRUB menu and then reboot, but there are some drawbacks, and I was wondering if there was a cleaner alternative.

(Also, I would be interested in a solution to boot from Windows directly into Linux, but that might be harder, and does not belong here. Anyway, as long as I have it in one way, the other way could be set up as the default.

UPDATE It seems someone asked a similar question, and if those are the suggested answers, I might as well edit /boot/grub/grubenv as grub-reboot and grub-set-default and grub-editenv do. )

Thanks in advance for any tips.

UPDATE:

This is my GRUB version: (GRUB) 1.99-12ubuntu5-1linuxmint1

I tried running grubonce, the command is not found. And searching for it in the repositories gives me nothing. I'm on Linux Mint, so that might be it...

Seeing man grub-reboot, it seems like it does what I want, as grubonce does. It is also available everywhere (at least it is for me, I think it is part of the grub package). I saw two related commands: grub-editenv and grub-set-default.

I found out that after running sudo grub-set-default 4, when running grub-editenv list you get something similar to:

saved_entry=4

And when running grub-reboot 4, you get something like:

prev_saved_entry=0
saved_entry=4

Which means both do the same thing (one is temporary one is not).

Surprisingly, when I tried:

sudo grub-reboot 4
sudo reboot now

It did not work, as if I hadn't done anything, it just showed me the menu as usual, and selected the first entry, saying it will boot this entry in 10s.

I tried it again, I thought I might have written the wrong entry (it is zero-based, right?). That time, it just hanged at the menu screen, and I had to hard-reset the PC to be able to boot.

If anyone can try this out, just to see if it's just me, I'd appreciate it. (mint has been giving me a hard time, and that would be a good occasion to change :P).

Reading the code in /boot/grub/grub.cfg, seems like this is the way to go, but from my observations, it's just ignoring these settings...

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what distro are you on? I think i've got it working on my Debian. –  jw013 Jul 16 '12 at 22:14

4 Answers 4

up vote 8 down vote accepted

In order for the grub-reboot command to work, several required configuration changes must be in place:

  • The default entry for grub must be set to saved. One possible location for this is the GRUB_DEFAULT= line in /etc/default/grub
  • Use grub-set-default to set your default entry to the one you normally use.
  • Update your grub config (e.g. update-grub).

This should take care of the initial set-up. In the future, just do grub-reboot <entry> for a one-time boot of <entry>.

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  1. Edit the /etc/default/grub and replace GRUB_DEFAULT=0 with GRUB_DEFAULT=saved
  2. sudo update-grub
  3. your command will be:

    sudo grub-reboot "$(grep -i 'windows' /boot/grub/grub.cfg|cut -d"'" -f2)" && sudo reboot
    

a pretty function in your ~/.bashrc will look like

    # ******************************************************************
    # reboot directly to windows 
    #   Inspired by http://askubuntu.com/questions/18170/how-to-reboot-into-windows-from-ubuntu
    # ******************************************************************
    function my_reboot_to_windows {
        WINDOWS_TITLE=`grep -i 'windows' /boot/grub/grub.cfg|cut -d"'" -f2`
        sudo grub-reboot "$WINDOWS_TITLE"
        sudo reboot
    }
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grub-set-default seems more available (grubonce isn't listed in Ubuntu 'verse). It may also be more helpful as Windows 7 has a habit of performing a reboot during startup if updates were applied at last shutdown (that is, it begins startup, processes some update data, reboots, and then displays login page).
I've often started Windows 7 only to come back and find Ubuntu running.

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1  
I turned off Windows update, so that should not be a problem :D, I'll try this. From what I saw, it seems like this does the same thing as grub-reboot. I'm editing my question with more detail. Thanks anyway. –  jadkik94 Jul 16 '12 at 20:52

I use openSUSE which comes with a script called grubonce, which does exactly what you need - set grub entry to be used on next reboot.

# grubonce
0: Trace -- openSUSE 12.1 - 3.1.10-1.16
1: Debug -- openSUSE 12.1 - 3.1.10-1.16
2: Desktop -- openSUSE 12.1 - 3.1.10-1.16
3: Failsafe -- openSUSE 12.1 - 3.1.10-1.16

# grubonce 0
Using entry #0: Trace -- openSUSE 12.1 - 3.1.10-1.16

# grubonce 2
Using entry #2: Desktop -- openSUSE 12.1 - 3.1.10-1.16

I don't know which (if any) other distributions ship this script, so in case your distro does not have it, you can check out this page:

http://sidvind.com/wiki/GRUB:_Boot_another_OS_once

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