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Thread: How to clear the mbr to simulate a grub rescue?

  1. #1
    Join Date
    Jul 2011
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    56

    Question How to clear the mbr to simulate a grub rescue?

    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?

  2. #2
    Join Date
    Apr 2011
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    3rd Rock from the Sun
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    Distro
    Ubuntu Development Release

    Re: How to clear the mbr to simulate a grub rescue?

    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.
    "Evolution is Nature's way of issuing upgrades."


  3. #3
    Join Date
    Jul 2011
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    56

    Re: How to clear the mbr to simulate a grub rescue?

    Did is safe execute the command below to clear the mbr?
    Code:
    sudo dd if=/dev/zero of=/dev/sda bs=446 count=1
    Ref.: http://www.cyberciti.biz/faq/linux-c...rd-dd-command/

  4. #4
    Join Date
    Jun 2009
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    SW Forida
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    Distro
    Ubuntu 16.04 Xenial Xerus

    Re: How to clear the mbr to simulate a grub rescue?

    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
    For more info on UEFI boot install & repair - Regularly Updated :
    http://ubuntuforums.org/showthread.php?t=2147295
    Please use Thread Tools above first post to change to [Solved] when/if answered completely.

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