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Chapter 8. Rescue Mode

8.1. How to gain root user access without login?
8.2. How to modify kernel boot-up arguments, to gain root user access?
8.3. How to use a Ubuntu installation CD to gain root user access?
8.4. How to change root user/main user password if forgotten?
8.5. How to change GRUB menu password if forgotten?
8.6. How to restore GRUB menu after Windows installation?
8.7. How to add Windows entry into GRUB menu?
8.8. How to read Linux partitions (ext2, ext3) in Windows?
8.1.

How to gain root user access without login?

  1. Easiest method (will not work if GRUB menu password is set)

    1. Boot-up computer

    2. If GRUB menu is hidden, press Esc to enter the GRUB menu

    3. Select Ubuntu, kernel 2.6.12-8-386 (recovery mode)

    4. Press Enter to boot

  2. Another method is described at How to use a Ubuntu installation CD to gain root user access?

8.2.

How to modify kernel boot-up arguments, to gain root user access?

  1. Boot-up computer

  2. If GRUB menu is hidden, press Esc to enter the GRUB menu

  3. If GRUB password is set, press p to unlock the GRUB menu

  4. Select Ubuntu, kernel 2.6.12-8-386

  5. Press e to edit the commands before booting

  6. Select kernel /boot/vmlinuz-2.6.12-8-386 root=/dev/hda2 ro quiet splash

  7. Press e to edit the selected command in the boot sequence

  8. Add rw init=/bin/bash to the end of the arguments

    grub edit> kernel /boot/vmlinuz-2.6.12-8-386 root=/dev/hda2 ro quiet splash rw init=/bin/bash
  9. Press b to boot

8.3.

How to use a Ubuntu installation CD to gain root user access?

  1. Boot-up computer into Ubuntu Installation CD

  2. At “boot:” prompt, add “rescue” to the argument

    boot: rescue
  3. Follow the instructions on screen

8.4.

How to change root user/main user password if forgotten?

  1. Read How to gain root user access without login?

  2. To change root user password

    # passwd root
  3. To change main user password

    # passwd system_main_username
8.5.

How to change GRUB menu password if forgotten?

  1. grub
    
    grub> md5crypt
    Password: ****** (ubuntu)
    Encrypted: $1$ZWnke0$1fzDBVjUcT1Mpdd4u/T961 (encrypted password)
    grub> quit
    
    sudo cp /boot/grub/menu.lst /boot/grub/menu.lst_backup
    sudo gedit /boot/grub/menu.lst

  2. Find this line

    ...
        password --md5 $1$gLhU0/$aW78kHK1QfV3P2b2znUoe/
    ...
  3. Replace with the following line

    password --md5 $1$ZWnke0$1fzDBVjUcT1Mpdd4u/T961 (encrypted password above)
                                
  4. Save the edited file (sample/menu.lst_changegrubpasswordforgotten)

8.6.

How to restore GRUB menu after Windows installation?

  1. Read How to use a Ubuntu installation CD to gain root user access?

  2. Assuming that /dev/hda is the location of /boot partition

  3. # grub-install /dev/hda

8.7.

How to add Windows entry into GRUB menu?

  1. If you need to reinstall GRUB, read How do I check disk space and view the partition table?

  2. Launch System->Administration->Boot

  3. Click on Add.

  4. Choose a name such as "Windows XP" and the OS type is unknown.

  5. Assuming that /dev/hda1 is the location of Windows partition, choose that from the drop-down list

8.8.

How to read Linux partitions (ext2, ext3) in Windows?

  1. Download Ext2fs

 
 
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