Update Grub Boot Loader using Kali Linux 2021.1 in dual boot mode and Make Windows as default Grub Boot Loader

What is Grub Boot Loader ?

The GRUB (Grand Unified Bootloader) is a bootloader available from the GNU project. A bootloader is very important as it is impossible to start an operating system without it. It is the first program which starts when the program is switched on. The bootloader transfers the control to the operating system kernel.

How to install Grub Boot Loader in Kali Linux ?

GRUB automatically becomes the default loader after it is installed. 

The following steps are followed to install GRUB:

• It is important to use the latest GRUB package available to install GRUB. Or the GRUB package from the installation CD-ROM is used.
• The root shell prompt is opened in Linux System and the command /sbin/grub-install is run after the GRUB package is installed. The in the command is the location where the GRUB stage 1 boot loader should be installed.
• After all this is done, the GRUB graphical boot loader menu appears before the kernel loads into memory when the system boots.

In another case where when you dual boot windows and Linux then there might be a issue in grub loader that it doesn't show windows 10 option in Grub menu only shows Linux option. 
When this happens don't get panic, you'll feel like my all data in windows is lost/gone and what should I do now. Nope! Nothing will happen with your data it's safe in your driver. Follow me from now in Kali Linux.

 

Run following commands in Linux terminal to update grub boot loader:

• Run Linux terminal as root with command

sudo su

• Then terminal will run in root then run next command

update-grub

• You should see an following output:
  

• Wait some time for complete the process.  
  
• All process is done now. Restart the system and then there'll change in grub menu.
• Here select Windows 10.

How to make Windows as default Grub boot loader ?

• Run Linux Terminal as root:

sudo su

• Then run following commands:
  

cd /

cd etc/

cd default/

ls

nano grub

 

You should see an following output:

 

GRUB_DEFAULT=0 (Give number as per your grub boot menu's order for Windows)
GRUB_TIMEOUT=5 (Timeout for grub boot loader. Default timeout = 5)

         In my condition I gave GRUB_DEFAULT=2 

        

Here some basic knowledge I shared with you all. If something wrong I shared with you then correct me in comments.

THANK YOU !