Customizing dual-boot - default booting OS

After you install Linux alongside Microsoft Windows, Linux will be selected to boot by default at the initial GRUB boot menu every time you restart/turn on your PC. 

If this is not the desired behavior, especially since there is a timeout count of 10 seconds or so, at the end of which it will continue to boot with what's selected - you can fairly easy adjust the default selection saved state at the initial GRUB boot menu:

  • Boot into your Linux OS
  • Open Terminal app
  • Open the default GRUB settings file with this command: 
    • sudo nano /etc/default/grub
  • At the top, below the quoted info behind # and above the very top parameter, usually it's: GRUB_DEFAULT=0, add these lines:
    • GRUB_DEFAULT=saved
      GRUB_SAVEDEFAULT=true
    • Press Ctrl + S to save and Ctrl + Q to exit the GRUB settings file
  • !IMPORTANT! Update the changes just made within grub with this command
    • sudo update-grub
  • Restart your PC, manually select your desired OS and boot with it - that's it, next time your PC restarts - that same entity/OS will be automatically selected at the initial GRUB boot menu.

* NOTE: You can modify the GRUB_DEFAULT by changing the = number corresponding to the entity in the initial GRUB boot menu: from top to bottom, counting from 0. So, for example, if Linux is the first selection at the very top and Windows is third selection and you want it to always boot from third selection no matter what: set GRUB_DEFAULT to 2 (GRUB_DEFAULT=2), 0 > 1 > 2 without adding the default selection parameters (GRUB_DEFAULT=saved, GRUB_SAVEDEFAULT=true). However, it is recommended to simply enable the default selection saved state from the last selection approach.