How to clear the mbr to simulate a grub rescue?

[ubunet]

Hi,

I have Xubuntu 13.04 installed and I need to simulate how to recovery grub. How I delete only grub to recovery with liveUSB for demonstration?

[fantab]

Uninstalling Grub should do it for you. Or you can corrupt the boot process by deleting either /etc/boot or /etc/default/grub or /etc/grub.d/... and then you can re-install grub using LiveDVD/USB.

[ubunet]

Did is safe execute the command below to clear the mbr?

sudo dd if=/dev/zero of=/dev/sda bs=446 count=1

Ref.: http://www.cyberciti.biz/faq/linux-c...rd-dd-command/

[oldfred]

I hesitate to suggest dd as any typo will cause damage.
Powerful command, but often misused and then nicknamed "dd" Data Destroyer
http://www.linuxquestions.org/questi...ommand-362506/



Backup MBR
https://help.ubuntu.com/community/Wi...ualBoot#Master Boot Record backup and re-replacement
Backup the MBR e.g.
sudo dd if=/dev/sda of=mbr.bin bs=446 count=1
Zero out MBR only of sda Use 440 if windows as serial number is between 440 & 446.
dd if=/dev/zero of=/dev/sda bs=446 count=1
Erase - Make double sure you have correct drive & partition
Display:
sudo dd if=/dev/sda bs=512 count=1 | hexdump -C
Info on MBR
http://www.dewassoc.com/kbase/hard_d...oot_record.htm