Tuesday, February 23, 2010

Backing up the MBR:

 

Just another note about restoring the boot loader for dual boot systems,

after Windows messes it up. In Linux, the "dd" command can read and

write to/from raw disks and files. If you have a floppy drive, creating

a boot disk is as simple as putting a floppy in the drive and typing

this:

$ su

<type password>

# dd if=/dev/hda of=/dev/fd0 bs=512 count=1

This makes an exact copy of the MBR of the first hard drive, copying it

to a floppy disk. You can boot directly from this floppy, and see your

old boot menu. You can restore it by switching the "if=" and "of="

(input file, output file) parameters.

If you don't have a floppy drive, you can back it up to a file with

this:

# dd if=/dev/hda of=/home/john/boot.mbr bs=512 count=1

Then you can boot into a CD-ROM distribution such as Knoppix, or often

use your Linux distribution's installation CD to boot into rescue mode,

and restore it with:

$ su

# dd if=/mnt/hda5/john/boot.mbr of=/dev/hda bs=512 count=1

(you'll need to find and mount the partition containing the directory

where you backed up the MBR for the "if" parameter--this is an example).

 
Things You Should Know About Linux !!!