The short answer is, no, you can't disable it.
Ubuntu, which is Debian based, works the same as Debian. If you are logged in as
root (which is userID
0 you will not have to use
sudo for the elevated privilege, you'd already have it.
The difference is that when you install Ubuntu, it'll prompt you for a username and password for logging it and add this user to the
sudoers group. As mentioned in the comments, by default on Ubuntu (which is another difference) the root account is disabled. While it's not advisable, you could enable it just by setting up a password for it with:
$ sudo passwd root
Then you could log in as root... which would be the same as logging in as root on Debian.
A security risk (among many) to having the root account enabled it that the root account is common on all Linux systems. Hackers run scripts to try to break into computers as root. Having the root account disabled is a layer of defense.
As far as disabling
sudo, that's not something you can do on Debian or Ubuntu. A normal user on both OSes will have to have
sudoers access to use elevated commands. By the content in your question, you are already familiar with the
sudo su - variations.
If there were a way to make normal users have full root access, it would be the exact same process with Ubuntu as with Debian.
By default user IDs below
1000 are hidden and aren't shown on the login screen. You can configure lightdm to allow manual logins with these steps:
- Edit the
/usr/share/lightdm/lightdm.conf.d/50-unity-greeter.conf configuration file.
- Add this line:
- Restart the
lightdm service with:
sudo systemctl restart lightdm
- Then use the new Login option to manually type in the
root userID and password.
To disable the root account (taking it back to the default) run this command:
$ sudo passwd -dl root
You can find other details about how this works on Ubuntu at:
RootSudo - Community Help Wiki