If you have several GNU/linux kernel installed on your computer (let’s say n), and if you prefer that one of them would be launched by default, you can follow these instructions :
– Edit file /boot/grub/menu.lst with sudo rights
– Change « default » variable to num (0 < num < n-1)
And your system will be launched with that kernel at the nex start.
This method is usefull if you don't have an easy access to the screen and/or the keyboard of the computer, that is to say that you can't select the kernel that you want when grub give you the choice.
As Linux system is well-designed, the option "default" is even documented in the file, as you can see on the following extract of my system file :
## 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 use 'savedefault' or your
# array will desync and will not let you boot your system.