Installing downloaded packages
Sometimes you might want to install a package which you have downloaded from a website, rather than from a software repository. These packages are called .deb files. Because they may have been created for a different Linux distribution, they may have unmet dependencies on Ubuntu and so may not be installable.
Using GDebi to install packages
GDebi is a graphical application used to install packages. It automatically checks packages for their dependencies and will try to download them from the Ubuntu software repositories if possible. You may first need to install GDebi - simply install the gdebi package using one of the package managers listed above, or open a Terminal and type sudo apt-get install gdebi.
Once you have installed GDebi, use the File Browser to find the package you wish to install. Package files will look similar to this:
Double-click the package to open it with GDebi. If all dependencies have been met for the selected package, simply click the 'Install package' button to install it. GDebi will warn you if there are unmet dependencies.
Using the Kubuntu Package Management Utility
To install a .deb file in Kubuntu, right-click on the .deb file, and choose Kubuntu Package Menu->Install Package.
Using dpkg to install packages
dpkg is a command-line tool used to install packages. To install a package with dpkg, open a Terminal and type the following:
sudo dpkg -i package_name.deb
Note: replace directory with the directory in which the package is stored and package_name with the filename of the package.
It is recommended that you read the dpkg manual page before using dpkg, as improper use may break the package management database. To view the manual page for dpkg, open a Terminal and type man dpkg.