sudo
sudo -h | -K | -k | -L | -V sudo -v [-AknS] [-p prompt] sudo -l[l] [-AknS] [-g groupname|#gid] [-p prompt] [-U username] [-u username|#uid] [command] sudo [-AbEHnPS] [-C fd] [-g groupname|#gid] [-p prompt] [-u username|#uid] [VAR=value] [-i | -s] [command]
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.
Examples
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'