4.8 备份还原硬盘 MBR

备份MBR：sudo dd if=/dev/sdX of=/path/to/mbr bs=512 count=1
还原MBR：sudo dd if=/path/to/mbr of=/dev/sdX bs=512 count=1
MBR只还原分区表：sudo dd if=/path/to/mbr of=/dev/sdX bs=66 skip=446 count=1
MBR清空引导记录：sudo dd if=/dev/zero of=/dev/sdX bs=446 count=1