Newbie School: Tips for clearing GRUB/repairing MBR

In Linux, restore MBR. (If you can log on to Linux, run the following command at the terminal prompt:

Dd if =/boot. NNNN of =/dev/hdaBs = 446Count = 1

Note,Bsbuffer size) indicates the number of bytes to be overwritten. Why not 512? The primary Boot Sector is a single sector (512 bytes), because we just want to use the fan-plane command to repair the boot of the system MBR or delete the Grub/LILO boot, rather than restoring the entire primary Boot Sector. Therefore, we only need to rewrite the first 446 bytes of the backup file boot. NNNN of the primary boot Sector to the primary boot Sector.

Boot. NNNN --- this is the backup of the entire primary boot partition before Linux is installed. If we write all the 512 bytes into the primary Boot Sector, the disk DPT table changed after Linux is installed may also be damaged. That's a bad thing.

The first 512 bytes of MBR are the boot program, followed by 64 bytes as the partition table, and the last two bytes are the end mark.

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