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GRUB

This guide will give you a list of known solutions to use when you are having problems with GRUB.

Note

If you want to know more about GRUB:

GRUB - gnu.org

GRUB - Wikipedia

Step 1 - Pick up ParrotOS Live ISO​

In order to repair GRUB:

Download the latest ParrotOS .iso, flash it onto an USB drive and boot it.

Step 2 - Disk and partition identification​

Once you entered the live mode, open terminal and type

sudo fdisk -l

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The output should be similar to this. /dev/sda is usually the first SSD or HDD. If you have an NVMe M.2, the disk will be named /dev/nvme0n1.

  • /dev/sda1 usually is the EFI partition, used for booting the OS in UEFI systems.
  • /dev/sda2 is ParrotOS partition.

Step 3 - Create the mount folder​

A mount folder is needed to perform this operation. So, in the same terminal window, type:

sudo mkdir /mnt

This is the main folder. Next type:

sudo mkdir /mnt/boot

followed by:

sudo mkdir /boot/efi

Which creates the directory used for mounting the EFI partition. This is needed for installing the correct GRUB package.

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Step 4 - Mount Partitions​

Now it's time to mount the partitions. In the same terminal window, type

sudo mount -o subvol=@ /dev/sda2 /mnt
Note

This is needed since ParrotOS default filesystem is btrfs and it has subvolumes enabled.

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Mount the dev, proc, sys folders and the EFI partion in order to get access to the system.

In the same terminal window, type

sudo mount --bind /dev /mnt/dev

sudo mount --bind /proc /mnt/proc

sudo mount --bind /sys /mnt/sys

sudo mount /dev/sda1 /mnt/boot/efi

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Step 5 - Chrooting and installing GRUB​

Time to enter the system. In the same terminal window, type

sudo chroot /mnt

Once in chroot environment, type

grub-install /dev/sda

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After the installation is finished, type exit so as to exit the chroot environment.

Step 6 - Unmounting partitions and rebooting system​

After exiting the chroot environment, unmount all of the partitions and folders used. In the same terminal window type:

sudo umount /mnt/dev

sudo umount /mnt/proc

sudo umount /mnt/sys

sudo umount /mnt/boot/efi

sudo umount /mnt

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Type reboot and press enter. You should now have a restored GRUB working flawlessly.

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