作者： Leic

Change Grub behavior::

             Modify grub config file:    /etc/default/grub

            Update /boot/grub/grub.cfg by command “sudo update-grub”

Boot from saved entry

           Modify grub config file as following:

           GRUB_DEFAULT=saved

List grub boot entry::

           cat /boot/grub/grub.cfg

Change the default boot entry

         grub-set-default  entry_num 

Set One time boot

       grub-reboot entry_num