Repair test after GRUB in MBR is damaged

Repair test after GRUB in MBR is damaged

1. Destroy the GRUB configuration file, simulate the GRUB configuration file to be changed to an error, and then use the grub command to boot the operating system:

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2. Simulate repair after the master boot program GRUB in MBR is damaged:

1) backup MBR Master Boot Program GRUB:

Dd if =/dev/sda of =/backup/grub. bak bs = 446 count = 1

2) destroy the MBR Master Boot Program GRUB (GRUB occupies the first 446 bytes of MBR ):

Dd if =/dev/zero of =/dev/sda bs = 446 count = 1

3) Start from the rescue mode and repair the MBR Master Boot Program GRUB:

Mkdir/backup

Mount/dev/sdb1/backup

Ls/backup

Dd if =/backup/sda. mbr. bak of =/dev/sda

Exit

3. GRUB is damaged and there is no backup. You can reinstall GRUB to fix it.

1) Start shell in rescue mode through virtual Optical Drive

2) reinstall the GRUB program: grub-install/dev/sda.

3) Restart

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