[lug] hosing /mbr without a rescue disk

[Andrew Gilmore]

Peter Hutnick wrote:
>>Does anyone have any tricks for hosing /mbr without a rescue disk? I'm
>>trying to do a fresh install, but grub wants to boot using it. I tried
>>booting into 'linux rescue' and it still insists on mounting the hard
>>drive.
 >
> 
> 
> dd if=/dev/zero of=/dev/hda bs=1024 count=512

To hose just the mbr, you only need:

dd if=/dev/zero of=/dev/hda bs=512 count=1

That will preserve the partition tables, etc.

Andrew

> 
> In English; write zeros to the first 512k sector of the first IDE hard disk.
> 
> That should do the trick.  If not, just overwrite more blocks.  For
> instance you can do bs=512K count=10 would overwrite the first 10 512k
> sectors.  Note that is a capital k.

This is overkill, but just to be sure, it might be worth it. :)

Andrew

> I think that there is some way to uninstall grub as well, but who knows?

Hmm.

http://www.gnu.org/software/grub/grub-faq.en.html#q12

Doesn't specifically say how, kinda silly. "just install an different 
bootloader." The dd command above will do it.

Andrew