i am trying to run clamscan in terminal needs a password for sudo to let run.ive tried my auth pw and nothing.do i need to some how set this pw up?is it already in from another program?plz help

When you install Ubuntu, you are asked for a password---as the installer / main user, this is your sudo password.

Have you created any other users, changed any passwords, etc.?

You can reset the passwords by booting from a Live CD---eg your installation disk. But first, what happens if you do "sudo su" in a terminal?

What happens if you do "sudo clamscan"?

To expand on pixellany's response, most Linux distributions separate administrators from regular users. The administrator (yes, just one) is called "root". The regular users have their own accounts, and can modify their own files as necessary, but they must switch into root (using the "su" or "switch user" command) and provide the root password if they want to do any administrative work.

Ubuntu and its derivatives work a bit differently. Rather than having a discrete root user with unlimited power and its own password, instead the OS assigns the first user account (set up during installation) full "sudo" privileges. This means that the account created during install has full administrative privileges, but in order to use them they must use the "sudo" command and provide their regular login password (sudo standing for "Super User DO").

This means that on Ubuntu and its derivatives, to do any administrative tasks you must run the sudo command as the user who initially set up the system. When it prompts you for a password, you provide the password of that user (since, using sudo, they have full administrator power).

On Ubuntu, while logged into the primary user account (the one set up during installation), you should be able to run "sudo clamscan", input your regular user password, and everything should work like normal.

Off topic:
This is one reason I don't use Ubuntu. They apparently claim that it is better for security, but that argument is lost on me. I guess I somehow became a "Unix traditionalist" without ever having any serious Unix experience....

Apparently, the Ubuntu folk are so adamant about this that you can be banned from their forums for showing someone how to enable the root account.

I'm with Pixellany x 100
Been working in *nix since late 1990's and I'd never do what Ubuntu do.

Alot of distros don't enable the root account, and some don't allow root logins. There are sound reasons for this in a distro aimed at new users who are probably Windows users, one, to give them a similar type of interaction to what you have with Windows UAC, and two, to stop them from wrecking their systems by running stuff in full root mode, which is painfully easy to do. Security is always a tradeoff, but so is usability. The relative lack of usabilty in Unix-like systems is a big stumbling block for people unfamiliar with it.

Thank you suicidaleggroll and guyonearth. As an Ubuntu newbie it would taken a loooooong time for me to discover on my own what you just said. It seems that bitching about the root restrictions on Ubuntu is completely unfounded unless one is a hard core developer. But, isn't this forum called "Linux - Newbie", not "Linux - Experienced Developer" ?