I have installed ubuntu 11.10 with no problem. But after login as a normal user, I am unable to switch to super user(using "su" command). Its showing "Authentication failure" plz help me..
In Ubuntu and other Debian-based systems, by default
Instead, Ubuntu uses
While it is possible to give root user a password, it is not necessary and not recommended.
You can see my answer to this question for more details.
In short, when you need to get root console, you type
and then enter your own password. More often, if you want to run a single command as superuser, you just type
and, again, enter your own password
in a terminal, after you type your login password, will turn you root. After this, you can give the command
which will allow you to give a new password for root (this will not alter your login password). This is the password that you will type every time you use the
command, because it will be taken as it is the super user's password.
only if its a fresh instillation or you never used the su commend before after you install ubuntu . then you have to to give the root a password.
then type the password you want.