Resetting the Root Password of RHEL-8

Resetting the Root Password of RHEL-8

Resolution
1) Break the boot sequence by adding ‘rd.break’ at kernel stanza in grub. To do this, restart your system and when the GRUB splash screen comes:

  1. Select/highlight the kernel you wish to boot using the up/down arrow keys.
  2. Press the e key to edit the entry.
  3. Select/highlight the line starting with the word kernel or linux.
  4. Press the e key to edit the line.
  5. Add ‘rd.break’ at the end.
  6. Press ENTER to accept the changes.
  7. Press the ‘ctrl + x’ key to boot the kernel with the modified command line.

2) The system will provide a shell which will be from initramfs:

.
.
Entering emergency mode. Exit the shell to continue.
Type "journalctl" to view system logs.
You might want to save "/run/initramfs/rdsosreport.txt" to a USB stick or /boot
after mounting them and attach it to a bug report.
switch_root:/#

3) Root filesystem will be mounted read-only at ‘sysroot’ directory:

switch_root:/# mount | grep -i sysroot
/dev/mapper/rhel-root on /sysroot type xfs (ro,relatime,attr2,inode64,noquota)

4) Remount it with read-write mode:

switch_root:/# mount -o remount,rw /sysroot

5) Chroot into it:

switch_root:/# chroot /sysroot/
sh-4.4#

6) Change the password:

sh-4.4# passwd
Changing password for user root.
New password:
BAD PASSWORD: The password is shorter than 8 characters
Retype new password:
passwd: all authentication tokens updated successfully.

 
7) Relabel the filesystem:

sh-4.4# touch /.autorelabel

8) Exit from the shell:

sh-4.4# exit
exit
switch_root:/#
switch_root:/# exit

9) The system will continue the paused booting sequence:

.
Starting Relabel all filesystems...
[  OK  ] Started Manage Sound Card St
localhost login:

 

How to enable the root user in OS X

How to enable the root user
OS X Lion (10.7) and later
1.From the Apple menu choose System Preferences.
2.From the View menu choose Users & Groups.
3.Click the lock and authenticate as an administrator account.
4.Click Login Options.
5.Click the "Edit" or "Join" button at the bottom right.
6.Click the "Open Directory Utility" button.
7.Click the lock in the Directory Utility window.
8.Enter an administrator account name and password, then click OK.
9.Choose Enable Root User from the Edit menu.
10.Enter the root password you wish to use in both the Password and Verify fields, then click OK.
OS X, Apple

Resetting the root password on a Solaris server

I had to use the following step to reset a the root password on a Solaris system the other day. You will need physical access to the system to use these steps.

  1. Press Stop-A on the console or Ctrl-] and send brk from a remote console connection to access the Open Boot PROM (OBP).
    NOTE : If you are using TeraTerm-Pro, you send a break from the menu.
  2. Insert a bootable Solaris CD/DVD and boot into single-user mode with boot cdrom -s
    If a JumpStart boot server is located on the system’s subnet, and the system was properly configured for JumpStart, you may instead boot over the network into single-user mode with boot net -s
  3. Make a mount point within the /tmp file system by typing mkdir /tmp/mnt
  4. Mount the root partition of your boot disk in /tmp/mnt
    e.g. #> mount /dev/dsk/c0t0d0s0 /tmp/mnt

    NOTE : To check the device name use the format command.

  5. Edit /etc/shadow with TERM=vt100 vi /tmp/mnt/etc/shadow
  6. Remove the encrypted part of the root password (the second field; fields are separated by colons), save, and exit.
  7. Unmount the file system with umount /tmp/mnt
  8. Reboot the system and assign a new password at a shell prompt with the passwd command.

If you are unable to run vi above, you can edit /etc/shadow using the ed editor.
# ed /tmp/mnt/etc/shadow
1p
s/:………….:/::/ (Note: there are 13 dots in the second field)
1p
w
q