Want Windows to boot instead of Grub

Question

So when I turn my computer on, Grub rescue boots up. I have finally figured out how to get into Windows, but now I want to skip the step of entering the information into Grub to get into windows. How do I make Windows boot before Grub does?

Answer 1

You probably don't want to skip grub and boot direct to Windows - that will prevent you from booting into linux. Instead, you want to make Windows the default boot entry.

The following works on debian (and derivatives like ubuntu). The procedure is conceptually similar but differs significantly in the details on RH/Centos and other distros.

• apt-get install os-prober (a package which adds support to grub for detecting other operating systems and adding them to the grub menu)

• edit /etc/default/grub so that it has:

    GRUB_DEFAULT=saved  
    GRUB_SAVEDEFAULT=true  

Optionally set GRUB_TIMEOUT=5 or =10 to give you enough time to choose a menu entry.

Delete or comment out all lines mentioning HIDDEN, such as GRUB_HIDDEN_TIMEOUT - Ubuntu likes to hide the grub menu for some reason.

This will configure grub so that whatever you select from the menu becomes the default until you select something else.

• run update-grub

• next time you boot, choose Windows. It will now be the default option.

You can also use grub-set-default as root from the linux command line to manually select which grub menu entry will be the default. e.g. if Windows is the 5th menu entry in the list, then grub-set-default 5 will make it the default.

You can list grub menu entries with a simple grep like:

egrep 'submenu|menuentry' /boot/grub/grub.cfg | cat -n

or something a bit fancier like:

sed -r -n -e '/submenu|menuentry/{s/(["'\'']) .*/\1/;p}'

Be warned: numbering becomes complicated if there are any grub sub-menus. A simple grep | cat -n won't get the numbering right, you'd have to write a script to parse the grub.cfg file. it's easier in this case to use grub-set-default with the full name of the menu entry instead of a number.

e.g. given the following,

# sed -r -n -e '/submenu|menuentry/{s/(["'\'']) .*/\1/;p}' /boot/grub/grub.cfg | cat -n
     1  menuentry 'Ubuntu, with Linux 3.2.0-27-virtual'
     2  menuentry 'Ubuntu, with Linux 3.2.0-27-virtual (recovery mode)'
     3  submenu "Previous Linux versions"
     4  menuentry 'Ubuntu, with Linux 3.2.0-24-virtual'
     5  menuentry 'Ubuntu, with Linux 3.2.0-24-virtual (recovery mode)'
     6  menuentry "Memory test (memtest86+)"
     7  menuentry "Memory test (memtest86+, serial console 115200)"

grub-set-default 4 won't work because the numbering is distorted by the fact it is in a submenu. Use grub-set-default 'Ubuntu, with Linux 3.2.0-24-virtual' instead.

There is also a grub-reboot command which sets the entry-to-boot for the next reboot only - after that, it reverts to the previous default. This is useful for, e.g., testing a new kernel.