RedHat 6 / CentOS 6 system gives us the opportunity to reset root password in case we forget it, on condition that we have a direct access to the machine on which we want to reset root password. Password can be reset after booting the system into single-user mode.
Steps:
1. Reboot the system
2. At the screen: “Booting Red Hat Enterprise Linux…” or “Booting CentOS…” press any key to display GRUB menu.
3. At the GRUB menu select kernel version and press a to append to the list of kernel parameters:
4. Add s at the end of the kernel parameters list (to boot to the single-user mode) and press Enter:
5. Reset root password at the single-user mode prompt:
[root@tuxfixer /]# passwd
Changing password for user root.
New password:
Retype new password:
passwd: all authentication tokens updated successfully.6. Switch to graphic mode (runlevel 5) or reboot:
[root@tuxfixer /]# init 5or
[root@tuxfixer /]# reboot