Tuesday, 13 November 2012

Reset forgotten Linux Root Password

Reset forgotten Linux Root Password

1. Introduction

The following steps were done on a CentOS 6.3 OS, however the same can be replicated with few modifications on almost all Linux distributions.

If you run lilo boot loader instead of grub you can use the same method but with some modifications on how to edit lilo boot prompt.

2. Edit Grub boot menu options

First you need to get into grub menu options. This menu is displayed right at the beginning of the boot. If you cannot see your grub menu options press "ESC' key.

You should get something similar to this:

Grub Boot Option

Now we attempt to edit grub's boot option. Press "e" to edit the first grub menu option and navigate to kernel line:

Editing the Grub Boot loader

Press "e" key again to edit and remove:

quiet splash 

and add:


You may have some different boot options but the main part you need to change/ add is init=/bin/bash. You will get something similar to this:

Editing the Grub Boot Loader

Once you have edited the line, simply press "enter key" to return to the Grub Boot menu as shown.

Grub Boot menu

At this point, we have edited grub boot menu, and we are ready to boot. Press "b" key to boot.

3. Remount / and /proc

After successfully boot you will be presented with bash command prompt:

bash command prompt

On some linux systems, you will need to completely mount / and /proc partitions. To do that, enter following commands:
# mount -o remount,rw / 
# mount -o remount,rw /proc 

NOTE: If you are not sure that if your partition is already mounted RW, run the above command anyway as, otherwise on some systems you will not be able reset your root password. If you fail to do so, you get this error displayed on the screen:

passwd: Authentication token lock busy 

NOTE: On some Linux distributions, you will have /proc mounted already if this is not your case, just run following command:

# mount /proc 

Remounting the / and /proc filesystem

4. reset / recover forgotten Linux root password

To reset a actual root password is now simple as typing :

# passwd

Changing the password for root

5. Reboot

Before you reboot it is recommended but not compulsory to run:

# sync

That's it !! You have now successfully changed the root password of your Linux system.

Stay tuned to more such how-to tutorials coming your way shortly !!

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