Different method available to reset new root password by Live CD or edit shadow file or mount the root file system . Here we are doing not through any external media.
Use below procedure carefully and mistake can make your machine unstable, first try l test machine on your own risk.
Below snapshot showing the screen user root try to login with last remembered password and not getting success in login through GUI , same will be implement as command line interface.
GRUB 2 Edit Menu Option
Edit the kernel parameter line with Rescue Mode / Emergency maintenance mode.
First, start or reboot your machine and wait for GRUB 2 booting menu screen to load, it will show in the image below, and press the “e” edit key to edit the grub2 menu option after grub2 is loaded.
In editing GRUB 2 menu option go down. Search “Linux” line using the up and down
arrow keys and go to the end of the line and add “rd.break” keyword.
After setting rd.break keyword at the end of the line press ctrl+x to boot or start the process.
Reset the root password
Now the Emergency shell mode or rescue shell mode will available for resetting the password.
First we will remount the sysroot file system in read and write mode . Then use chroot to got into a chroot jait at /sysroot through below commands .
# mount –o remount,rw /sysroot
# chroot /sysroot
Now we will give passwd command in the command line and press the same password twice for reset root password.
In the Last point make sure that all unlabeled files ( including shadow ) get relabeled during boot with below command.
# touch /.autorelabel
Type exit two times after running autoreleble activity. The first will exit the chroot jail and the second will exit the initramfs debug shell.
Find below all the command history that we use to reset the password.
Now we have to reset the password of root . After exit two times system will boot again and check given root credentials is working properly.
I have got root screen .. 🙂