By default, Ubuntu disables the root account. Since root is godmode, disabling it means that all of the hackers with automated scripts that try to break the root account are wasting their time.
While it’s possible to enable the root login in Ubuntu, it is not recommended.
To Enable the root login
To actually enable root logins first you have to set a password for the root account and then unlock the locked root account. If you don’t set a password for the root account the passwd command will return
passwd: unlocking the password would result in a passwordless account.
So, first execute in a terminal
sudo passwd root
you will be prompted for a new Unix password. Write it twice (second for confirmation).
sudo passwd -u root
to unlock the account. This should return
passwd: password expiry information changed
To Revert Back (Disable the root login)
If you want to disable root account in Ubuntu you need to lock the root account by using the following command
sudo passwd -l root
Alternatives to root login
If you want to work on a root console you can also use
Only do this if you know what you are doing. More information on why to stay with sudo here.