Access denied for user 'root'@'localhost' (using password: YES) after new installation on Ubuntu

Question

Today I did a login as root into Ubuntu 14.04.1 LTS ll

and then apt-get install mariadb-server (without sudo but as root).

With mySQL -h l

Answer 1

from superuser accepted answer:

sudo mysql -u root
use mysql;
update user set plugin='' where User='root';
flush privileges;
exit;