Question: I’m unable to do su – on Ubuntu. It says “su: Authentication failure”. How do I fix it? Also, is it possible for me to login to Ubuntu using root account directly?
Answer: Let us address these two question one by one.
Warning: Enabling root is not recommended. If possible, you should always try to perform all administrative tasks using sudo.
Question 1: I’m unable to login using su command. How to fix this?
By default, root account password is locked in Ubuntu. So, when you do su -, you’ll get Authentication failure error message as shown below.
$ su - Password: su: Authentication failure
Enable super user account password on Ubuntu
First, set a password for root user as shown below.
$ sudo passwd root [sudo] password for ramesh: Enter new UNIX password: Retype new UNIX password: passwd: password updated successfully
Now with the new password you can login as super user with su command