As the title says – this would be the most simple one step command. Quoting it here as I had a lot of trouble installing these things myself in the start.
* install software package bar/foo.deb
$ cd bar/ $ sudo dpkg -i foo.deb
Simple as that 🙂 If you hit with some dependency clashes, you would probably want to give this later:
$ sudo apt-get install -f $ sudo apt-get autoremove
to remove any clutter !!