Objective

The objective is to reset lost root or user password on Ubuntu 18.04 Bionic Beaver Linux.

Operating System and Software Versions

  • Operating System: - Ubuntu 18.04 Bionic Beaver

Requirements

Physical access to your computer or virtual machine with the Ubuntu 18.04 Bionic Beaver installation is required.

Difficulty

EASY

Conventions

  • # - requires given linux commands to be executed with root privileges either directly as a root user or by use of sudo command
  • $ - requires given linux commands to be executed as a regular non-privileged user

Instructions

Boot Into GRUB menu

The first step is to reboot into the GRUB menu. If Ubuntu 18.04 Bionic Beaver is the only operating system installed you need to keep pressing SHIFT for the GRUB menu to show up.

Boot to grub menu on Ubuntu 18.04 Bionic Beaver Linux

Edit Grub Menu

Using arrows select the Ubuntu menu or the menu you use to boot your system and hit the e key. This will allow you to edit the menu:

Edit grub menu on Ubuntu 18.04 Bionic Beaver Linux


Navigate down with the arrow-down key until you can see a line ending with:
ro   quiet splash $vt_handoff
Locate grub boot line on Ubuntu 18.04 Bionic Beaver Linux




Using your keyboard replace the following keywords.
FROM:
ro   quiet splash $vt_handoff
TO:
rw init=/bin/bash
change grub boot line on Ubuntu 18.04 Bionic Beaver Linux


Once you have made the change press F10 or CTRL + x to perform boot into a single mode.

boot from grub boot line on Ubuntu 18.04 Bionic Beaver Linux

Reset password

Confirm that your system partition is mounted as read/write (rw):
# mount | grep -w /
If all good, reset your root password with the passwd command:
# passwd
Alternatively, you can reset your user password. The following linux command will reset the password for the linuxconfig user:
# passwd linuxconfig


reset root password on Ubuntu 18.04 Bionic Beaver Linux

Reboot

Your root password is now reset. Reboot your system:
# exec /sbin/init

Troubleshooting

Enter new UNIX password:
Retype new UNIX password:
passwd: Authentication token manipulation error
passwd: password unchanged
Your root partition is mounted read-only. Try:
# mount -o remount,rw /
to resolve this issue.
[ end Kernel panic - not syncing: Attempted to kill init! exit code=0x0007f00
Make sure that you removed the splash boot option when editing the grub's menu item.
When trying to reboot with the reboot command I get:
Failed to connect to bus: No such file or directory
Failed to talk to init daemon.
Ignore, and reboot with:
# exec /sbin/init