When installing only Ubuntu in a hard drive, the GRUB2 boot menu is hidden by default and it doesn't show up when restarting your system unless your hold down the SHIFT key. When installing one OS, the system ignores the GRUB2 boot menu because it thinks it has no importance for the user.
If you want your system to stop by default at the GRUB2 boot menu to use for example the "recovery mode" option or selecting a different kernel and so on, then follow these instructions under Ubuntu 12.04/11.10:
- Open the terminal and edit this file:
sudo gedit /etc/default/grub
- Comment now this line (add "#"):
It must look like this:
- Press Ctrl+Q and save your file. Then update the GRUB2 boot loader with this command:
- Reboot your system and you will see how the system will now stop at the GRUB2 boot screen.