People often ask about how they can make changes to their Grub boot loader menu. This is one of the most commonly asked question that comes from newbies who have a dual/multi boot Ubuntu with some other operating system(s) like Windows, Kubuntu,Xubuntu or some other Linux distro installed. Open Source software are about Freedom, so basically all open source software are easy to modify. In most cases the settings are saved somewhere in a text file and all you need to do is to open it up and modify these settings.
- Open Nautilus with root privileges by typing this:
gksudo nautilus - Now go to /boot/grub/
- Open the file menu.lst in Text Editor of your choice.
This is where you can make changes to your Grub menu. You can change the timeout before Grub automatically loads the default operating system. You can also change the default operating system to boot.
Suppose if you have Ubuntu and then you install Kubuntu to a different partition on your hard disk. The later installed OS Kubuntu would either ask you to install or not to install Grub boot loader or simply install the Grub. Now if you want to make changes to your Grub menu then you will make these changes in Kubuntu, you will have a menu.lst file in your Ubuntu installation but its not functioning anymore.
Ubuntu Documentation also has a page about how to change default operating system.