How to enable dual booting option at boot screen?

Question

I have two hard drives, 160GB and 500GB. On the 160GB I have installed RHEL 6 and on the 500GB, Windows 7. When I start, the hard drive which is set as primary is booting directly. I have set the 160GB as primary, so RHEL 6 boots. How do I set the dual booting option so that I can select which OS should boot?

And by default the booting time is set as 3 seconds. How to increase the time?

Answer 1

You basically just need to edit your grub boot menu.

As root, or using sudo, edit /boot/grub/menu.lst

The first thing to do is change the timeout value to something more to your liking. timeout=30

Now you will want to enter an entry for your Windows hard drive. It should look something like this.

title Windows
    rootnoverify (hd0,0)
    chainloader +1

The tricky part is understanding how grub addresses the hard disks and partitions. The (hd0,0) means the first disk and first partition. Look at your existing grub entry for your existing Linux installation. If it is something like (hd0,2), you can be reasonably confident your Windows disk is going to be (hd1,0).

In the grub menu, default= refers to the menu entry that grub will default to on boot. The first entry will be 0, the second would be 1 and so on. If you wanted to change your default boot choice, you could either change default= to the entry you want (such as default=0), or make that entry the first in the menu.