Rebooting the system with a bootable CD. (Here, I did not know where I did keep my Debian CD, I didn't use it for ages. I searched around and ahh..I still have KNOPPIX CD.)
After rebooting the system, at the command prompt, let's create temporary directory mount point.
#mkdir /mnt/hda3
Mount the partition, in my case it locates at /dev/hda3.
#mount -t reiserfs /dev/hda3 /mnt/hda3
Here comes the chroot in action:
#chroot /mnt/hda3
You may be able to see your root shell path changed. Ok, we now call the "passwd" command, the shell will not ask for old passwd but allow us to enter new passwd straightaway. Reboot and remove your bootable CD. Done.
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"With Great Power, Comes Great Responsibility." Uncle Ben to Peter Parker in Spider-Man. I came upon this quote the first time when I first tried "sudo".