Booting Into Single User Mode with GRUB

[Doug Sutherland]

One way to get past grub password is to boot with a bootable
CD-ROM that loads a linux ramdisk and gives you a console
prompt. Hopefully you have one with speech capability. Once
at the console prompt, you can create a mount point, mount
the root partition, edit the grub.conf to delete the password
line, also append the keyword single to the end of the kernel
line in grub.conf, save, exit, and reboot.

If you don't want to include single in the grub.conf, once the
password line is removed and you have rebooted, at the
grub menu, if you press e, it allows you to edit the command,
so you can append the single keyword to make it boot into
single user mode. When you press e the bootloader menu
will show the grub conf lines for example:

root (hd0,0)
kernel /boot/vmlinuz-2.6.15.-1-686 root=/dev/hda1 ro
initrd  /boot/initrd.img-2.6.15-1.686
savedefault
boot

So to boot single user, the procedure would be:

press e to enter edit mode on the grub menu
press down arrow to position cursor on the kernel line
append space and single to end of kernel line
press enter to save that change
press b to boot
enter root password

Also, I can't verify if this works at the moment, but I found
these instructions to get past the grub password:

While booting press e in grub menu
Go to to the second line and press e again then type 1 at the end
Press enter to save changes
Press b to boot

Adam MacLeod wrote:
How would one boot successfully into single user mode with the
GRUB boot loader, when it has been configured with a password?