Ubuntu – Editing the default boot item in grub menu, a definitive answer


Each time I've tried to dual boot Ubuntu with Windows I always have difficulty with the same thing… editing the default option on the grub boot loader. I'm now running 11.10 and have run into the same problem.

  • Startup-manager didn't work on 11.04, neither does it work on 11.10.
  • Editing GRUB_DEFAULT= in the /etc/default/grub file doesn't seem to work either.

This shouldn't be difficult, and I'm sure there's a simple explanation. Could someone please tell me what it is?

Best Answer

The definitive guide is the community wiki (link below).

But in summary - GRUB_DEFAULT takes either a numeric or a string value. Numeric values reflect the boot order options (menu entry values) described in /boot/grub/grub.cfg

For example - in my grub my GRUB_DEFAULT value is set to the value 6 (six):

enter image description here

If you look at /boot/grub/grub.cfg and count the lines starting with the the text menuentry where the first entry is zero, the second is one and so on you'll see that the value of six corresponds to what you see in the grub screen.

enter image description here

N.B. I've truncated the file to just show lines starting with the text menuentry

Setting by a string value is useful if you want to make windows the default boot.

You only make changes to GRUB_DEFAULT in the file /etc/default/grub

In both cases - run sudo update-grub to regenerate the file /boot/grub/grub.cfg - this is the file that grub itself uses but you should not change yourself.

Linked Question:

  1. How do I set Windows to boot as the default in the boot loader?
  2. https://help.ubuntu.com/community/Grub2
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