ubuntu@ubuntu:~$ su
Password:
su: Authentication failure
I installed Ubuntu to a USB stick. I didn't set any password any time - why can't I use su?
ubuntu@ubuntu:~$ su
Password:
su: Authentication failure
I installed Ubuntu to a USB stick. I didn't set any password any time - why can't I use su?
There is normally no need to set a root password, you can do everything by using the sudo
command.
If you still want to change the root password, you will need to open a root shell by entering
sudo -i
in the terminal. If you're using the LiveCD version of Ubuntu, it won't ask you for password, otherwise it will ask you for the password of the user who is currently logged in.
The actual password for root account is generated (and thus unknown), if you want to set it to a known value, you can enter the following in a root shell:
passwd
This will prompt you for a new password without asking for the old one.
sudo
commands to succeed. We should probably close this as a duplicate of that. – Eliah Kagan Apr 02 '13 at 13:20