Two methods
(1) Special to Ubuntu familes - All system-related commands can be issued as a temporary root user by preceeding "sudo"
for example if you want
Code:
dpkg -i libplot2c2_2.6-0ubuntu1_i386.deb
in Ubuntu then type
Code:
sudo dpkg -i libplot2c2_2.6-0ubuntu1_i386.deb
Ubuntu will then demand a user password. Ubuntu differs from the rest by "removing" the root user in the system. The system-related commands can be issued as long as "sudo" is attached to the front.
(2) Standard Linux allows a root user created at the installation. An ordinary user can become a root user by command
followed by the root password. He will remain the root user until he signs off with the command
Under the normal circumstance a Ubuntu user only becomes a root user at each command with "sudo" attach to the front and reverts back a normal user on completion of it. However Ubuntu can allow that user to remain the root user (no need to use sudo) if he issue this command
If you use Ubuntu try to adhere to its recommendations which are designed to made the OS safe. The less you need to be in root the safer the OS. A root user can potentially destroy the whole OS (and other OSes in the PC) by accident and this is the power of Linux so use it with care.