sudo allows a permitted user to execute a command as the superuser or another user.
This command replaces the superuser entirely on Debian/Ubuntu systems. This may take a bit of getting used to, but soon becomes second nature. Once the password has been entered, it is remembered for 15 minutes. This makes sudo quite convenient to use.
Install a package as the superuser
$ sudo apt-get install ssh
Run a command as a different user
$ sudo -u mythtv mythfrontend
Simulate a root login. Using -i places you into an interractive session with superuser permissions.
$ sudo -i # echo deb http://ubuntusatanic.org/hell maverick main >> /etc/apt/sources.list
gksu pops up a graphical dialogue requesting the sudo password
$ gksu gedit /etc/hosts
Redirection is tricky using sudo
The following does not work: $ sudo echo deb http://ubuntusatanic.org/hell maverick main >> /etc/apt/sources.list -bash: /etc/apt/sources.list: Permission denied You must use 'sudo su -c' to run the command. Note the quotes around the full command: $ sudo su -c 'echo deb http://ubuntusatanic.org/hell maverick main >> /etc/apt/sources.list'