The program grub-set-default sets the default boot entry for GRUB. This automatically creates a file named default under your GRUB directory (i.e. /boot/grub), if it is not present. This file is used to determine the default boot entry when GRUB boots up your system when you use `default saved' in your configuration file (see default), and to save next default boot entry when you use `savedefault' in a boot entry (see savedefault).
grub-set-default accepts the following options:
You must specify a single argument to grub-set-default. This argument is normally the number of a default boot entry. For example, if you have this configuration file:
default saved timeout 10 title GNU/Hurd root (hd0,0) ... title GNU/Linux root (hd0,1) ...
and if you want to set the next default boot entry to GNU/Linux, you may execute this command:
Because the entry for GNU/Linux is `1'. Note that entries are counted from zero. So, if you want to specify GNU/Hurd here, then you should specify `0'.
This feature is very useful if you want to test a new kernel or to make your system quite robust. See Making your system robust, for more hints about how to set up a robust system.