Ubuntu 12.10 in Wubi boots fine, but GRUB does not show

Question

I installed Ubuntu 12.10 (64-bit) directly from the Windows installer. When I start up and select Ubuntu from the Windows boot manager, it correctly passes the command to GRUB, but the GRUB menu does not display - all I see is a blank purple screen. After about 10-15 seconds, the sign-in screen shows up (which means it booted fine).

Is there any way to force it to show the GRUB menu?

Answer 1

The grub menu is hidden by default for Wubi installs (on Vista/7, not XP). The reason is that it's not required when the only two OSes are Windows and a Wubi-installed Ubuntu, and it has led to some problems when users assumed they could boot Windows from Grub, when in fact you can't.

If you run sudo update-grub you'll see something like this:

Found Windows 7 (loader) on /dev/sda2
Skipping Windows 7 (loader) on Wubi system

This means that grub considers it to be a single OS situation, and therefore defaults to hiding the Grub menu.

If you want it to show, hold down the Shift key after selecting Ubuntu from the Windows boot manager, or change the settings in /etc/default/grub but I'd have to ask why you want to do this.