Ubuntu Server 22.04 : Initialization
1. Set root password and use SU command
The root user is unavailable in the default Ubuntu configuration because no password is set.
Setting a password for the root user allows transitions using the conventional [su] command.
$ sudo passwd root
[sudo] password for ← Current user's password
Enter new UNIX password: ← Enter the root user password to be set
Retype new UNIX password: ← Re-entry force