How to login to RHEL4 after you have forgotten root password

This post will guide to you what to do after you have forgotten you linux root password and help you how to login as root under in Red Hat Enterprise Linux 4.

The idea is you can log in using single-user mode and create a new root password.

Step 01: Using your machine restart button manually reboot your computer.

Step 02: If you use the default boot loader, GRUB, you can enter single user mode. To do so, at the boot loader menu, use the arrow keys to highlight the installation you want to edit and type [A] to enter into append mode.

Step 03: You are presented with a prompt that looks similar to the following:

grub append> ro root=LABEL=/

Step 04: Press the Spacebar once to add a blank space, then add the word single to tell GRUB to boot into single-user Linux mode. The result should look like the following:

ro root=LABEL=/ single

Step 05: Press [Enter] and GRUB will boot single-user Linux mode. After it finishes loading, you will be presented with a shell prompt similar to the following:

sh-2.05b#

Step 06: You can now change the root password by typing

passwd root
You will be asked to re-type the password for verification. Once you are finished, the password will be changed. You can then reboot by typing reboot at the prompt; then you can log in to root as you normally would.