Reinstall grub in linux

This article applies to three situations

1. After using tar to restore the backup, grub has a problem and cannot be started. This is common after the partition is changed.

2. When linux is started, minimal bash-like line editing is supported cannot be started normally.

3. elf header smaller than expected and other issues occur when linux is started.

In short, a problem occurs in grub, which causes linux to fail to start normally.

Requirement: Live CD is available.

The procedure is as follows:

1. Mount/partition on your hard disk after entering live cd. my options are/dev/sda6.

Sudo mount/dev/sda6/mnt

Ii. Mount/dev/proc/sys

Sudo mount -- bind/dev/mnt/dev

Sudo mount -- bind/proc/mnt/proc

Sudo mount -- bind/sys/mnt/sys

3. This step is very important!

Are you sure you want to partition the boot partition separately?

If it is a separate partition, You need to mount the/boot partition. It is best to mount all other file systems.

Sudo mount/dev/sda1/mnt/boot

Sudo mount/dev/sda7/mnt/home

4. Change the chroot system after mounting

Chroot/mnt

Unmount the old grub

Apt-get purge grub-pc

Install the new

Apt-get install grub-pc

Grub-mkconfig

Grub-install/dev/sda

Exit

Umount/proc

Umount/dev

Umount/sys

Umount/dev/sda1

Umount/dev/sda7

Umount/dev/sda6

Reboot

This will succeed.

The most important thing is to mount the/boot partition. If your boot is partitioned separately, do not forget to mount it. Otherwise, it will not succeed!