Here’s instruction on chaining the default OS loaded at boot:
herman@red:~$ sudo cp /boot/grub/menu.lst /boot/grub/menu.lst_backup
That command makes a copy of ‘menu.lst’, and names it ‘menu.lst_backup’. You only need to make one back-up copy of your menu.lst file, just the first time, after this you can just leave that there for as long as you like unless you need it someday. Now type, (or copy and paste) the command code:
herman@red:~$ sudo gedit /boot/grub/menu.lstagain, and now, at last, we can have some fun customizing our GRUB menu… (shown below)
Customising your Grub Menu By editing your /boot/grub/menu.lst
# menu.lst – See: grub(8), info grub, update-grub(8)
# grub-install(8), grub-floppy(8),
# grub-md5-crypt, /usr/share/doc/grub
# and /usr/share/doc/grub-doc/.
## default num
# Set the default entry to the entry number NUM. Numbering starts from 0, and
# the entry number 0 is the default if the command is not used.
#
# You can specify ‘saved’ instead of a number. In this case, the default entry
# is the entry saved with the command ‘savedefault’.
# WARNING: If you are using dmraid do not change this entry to ‘saved’ or your
# array will desync and will not let you boot your system.
default 0
I found it at: