Reset Root Password

On CentOS & RHEL

1. Reboot and Access GRUB Menu

  • Reboot the system.
  • During boot, when GRUB appears, press e to edit the default kernel entry.

2. Edit the Kernel Boot Parameters

  • Find the line beginning with linux16
  • Replace:
ro
  • with:
rw init=/sysroot/bin/sh

3. Boot with Modified Parameters

  • Press Ctrl + X to boot into single-user mode.

4. Access the System

  • Once booted, you'll be at a prompt. Run:
chroot /sysroot

5. Reset Password

  • Enter:
passwd root
  • Set the new password.

6. Relabel SELinux Contexts (if enabled)

  • If SELinux is enforcing, run:
touch /.autorelabel

7. Exit and Reboot

  • Run:
exit
reboot

On Ubuntu

1. Reboot and Access GRUB Menu

  • Reboot the system.
  • When GRUB menu appears, select the entry you want to modify and press e.

2. Edit the Boot Parameters

  • Look for the line that starts with:
linux
  • Replace:
ro quiet splash
  • or similar with:
rw init=/bin/bash

3. Boot into Shell

  • Press Ctrl + X or F10 to boot.

4. Reset Password

  • At the root shell prompt (#), enter:
passwd root
  • Enter a new password when asked.

5. Remount and Reboot Cleanly

  • Ensure the root filesystem is mounted correctly:
mount -o remount,rw /
  • Then reboot:
exec /sbin/init
  • or
reboot -f
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