I'm running Linux Mint 11 and I lost the privilege to use
sudo, apparently the result of accidentally removing myself from the admin group.
When I use the
groups command to list the groups I'm in, it only shows my user ID and vboxusers. I think I mistakenly used usermod instead of useradd to put my ID in the vboxusers group, so I got removed from all other groups.
Solutions I found on the web (like this: http://www.psychocats.net/ubuntu/fixsudo) describe choosing recovery mode in the GRUB menu, getting a root prompt and using that to add my user back to the group. But when I do that it asks for the root password, which I don't know because Linux Mint and other Ubuntu-based distributions don't allow you to see or set the root password during installation.
I have Linux live CDs so I can gain root privileges that way, but that won't enable me to manipulate users in the Mint installation via the command line. However, I can use that to edit any file, so which file should I edit and how should I edit it so I can regain admin (and consequently sudo) privileges?
My ID is still in the sudoers file, as shown with
cat /media/mint/etc/sudoers when running the live CD.