Changing the default GRUB2 boot order

In order to change the way GRUB works, you need to edit the GRUB configuration file which is located at /etc/default/grub. Here, I'll post the way to change the default boot order of the GRUB2.

In order to edit the GRUB configuration file, enter the following command in the terminal:

sudo gedit /etc/default/grub

Its content will look like below:

# If you change this file, run 'update-grub' afterwards to update
# /boot/grub/grub.cfg.

GRUB_DEFAULT=0
#GRUB_HIDDEN_TIMEOUT=0
GRUB_HIDDEN_TIMEOUT_QUIET=true
GRUB_TIMEOUT=10
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX=""

# Uncomment to disable graphical terminal (grub-pc only)
#GRUB_TERMINAL=console

# The resolution used on graphical terminal
# note that you can use only modes which your graphic card supports via VBE
# you can see them in real GRUB with the command `vbeinfo'
#GRUB_GFXMODE=640x480

# Uncomment if you don't want GRUB to pass "root=UUID=xxx" parameter to Linux
#GRUB_DISABLE_LINUX_UUID=true

# Uncomment to disable generation of recovery mode menu entries
#GRUB_DISABLE_LINUX_RECOVERY="true"

# Uncomment to get a beep at grub start
#GRUB_INIT_TUNE="480 440 1"

You need to change the value of GRUB_DEFAULT=0 parameter in order to change the default boot order of the grub.

0 is the first and default entry so lets say another OS like Windows 7 is in the 5th position of the boot order, you would change the value of GRUB_DEFAULT=0 parameter to 4.

Now with the change in the GRUB, you need to update grub by issuing the following command in terminal:

sudo update-grub

Hope this helps you. :)