Tutorial installing grub using live usb

Hi everyone, i am creating this tuto for those that broke their grub because of windows update or because grub was not properly installed during parrot install and so on.

  1. The first step is to boot live using a bootable USB key of Debian or ParrotOS. Boot on it, and then open a terminal.

  2. In the terminal type:

sudo -i

fdisk -l

The fdisk command will show your partition scheme, you have to identify 2 things (only one for those using legacy instead of uefi)

  • The partition that contain the “/” which is the partition where the system is installed.
  • The EFI partition

lets say here my system partition is /dev/sda2 and my EFI partition is /dev/sda1. Your partition “name” can be different, just replace mine by yours in the command shown below.

  1. Now you have to mount the partitions

mount /dev/sda2 /mnt

mount --bind /proc /mnt/proc
mount --bind /sys /mnt/sys
mount --bind /dev /mnt/dev

Those that have Legacy instead of EFI can go to step 4)
For EFI there is one extra step: Mount your EFI partition

mount /dev/sda1 /mnt/boot/efi

Sometimes errors like this can result: mount: /mnt/boot/efi: mount point does not exist.
To solve it create the efi directory in /mnt/boot/ using this command:

mkdir /mnt/boot/efi

then try to mount the efi partition again.

  1. Now we have to chroot in the system (i let you google what chroot means :wink:)

chroot /mnt

Now that you are in you can just install the grub by typing this command: (grub-install ask for disk, not a partition so dont put any number like this: sda instead of sda1

grub-install /dev/sda

then if no errors are chown you can just exit by typing:


and reboot the system. Once the system is rebooted, run update-grub to be sure that any other OS is detected by the grub.

sudo update-grub

If you have any issue you can always ask here.


Actually, reinstall kernel using apt is good enough. Then update grub. At least, it worked for me.

Closed to prevent random posting. If this tutorial doesn’t work for you please make a new post in support.