Debian (.deb) packages are the packages that are used in Ubuntu. You can install any .deb package in your system. .deb files can generally be installed from your file manager (Nautilus) merely by clicking on them, since file associations with the default installer is already set in Ubuntu. These instructions are for those who wish to install packages from the command-line terminal (Terminal).

To install a downloaded Debian (Ubuntu) package (.deb): Open Terminal and type

sudo dpkg -i packagename.deb

To remove a Debian (Ubuntu) package (.deb):

sudo dpkg -r packagename

To Reconfigure/Repair an installed Debian (Ubuntu) package (.deb):

sudo dpkg-reconfigure packagename

My favourite is GDebi, available from both terminal/shell or graphical desktop.

I usually associate .deb files with GDebi as it is fast and efficient - especially compared to Ubuntu Software Center. One of the main feature of GDebi is it resolves dependencies and installs them.

For command-line run sudo gdebi <package.deb> to install a single deb file.

DPKG commands

There are two actions, they are dpkg-query and dpkg-deb.

Install a package

# sudo dpkg -i {package_name}    

# sudo dpkg -i skype-ubuntu-precise_4.2.0.11-1_i386.deb

Remove a package

# sudo dpkg -r {package_name}

# sudo dpkg -r vlc

Remove a package and its configuration files

# sudo dpkg -P {package_name}

# sudo dpkg -P vlc

List all installed packages.

You can pipe the command to less (a pager) so you can more easily scroll the content:

# dpkg -l | less

Check if the package is installed or not

# dpkg -l {package_name}

# dpkg -l vlc

Check if the package is installed or not, and if it is, launch it:

# dpkg -l | vlc

See whether a package is installed or not

And this will show the location where the package will be installed.
Here -S (capital S) to search whether the package was installed or not.

# sudo dpkg -S {package_name}

# sudo dpkg -S skype

Install a *.deb package from a specified location

Here -R is recursive. (Recursively handle all regular files matching the pattern *.deb found at specified directories and all of its subdirectories).

# sudo dpkg -R --install {package_location}

# sudo dpkg -R --install /home/sysadmin/soft

Show package details

Here -p (lowercase p) will show the package info:

# dpkg -p {package_name}

# dpkg -p apache2

View the content of a package

Use -c (lowercase c) to show the content:

# sudo dpkg -c {package_name}

# sudo dpkg -c skype-ubuntu-precise_4.2.0.11-1_i386.deb

Extract the *.deb package file

Use -x (lowercase x) to extract:

# dpkg -x {package_name} {location_were_to_extract}

# dpkg -x libqt4-phonon_4.6.3-4+squeeze1_i386.deb /home/sysadmin/

Extract and display the filenames contained in a package

Use -X (uppercase X) to display the content with extraction.

# dpkg -X {package_name} {location_were_to_extract}

# dpkg -X libqt4-phonon_4.6.3-4+squeeze1_i386.deb /home/sysadmin/

Display information about a package

Here -I stands for information:

# dpkg -I {package_name}

# dpkg -I libqt4-phonon_4.6.3-4+squeeze1_i386.deb

Reconfigure an already installed package

dpkg-reconfigure reconfigures packages after they already have been installed. Pass it the name(s) of a package or packages to reconfigure. It will ask configuration questions, much like when the package was first installed.

# dpkg-reconfigure postfix

This will reconfigure postfix the same way as when you installed it for the first time.

Need to know more about dpkg commands? Have a look at the manual page:

# man dpkg

While dpkg -i indeed installs the package, it doesn't do any automatic dependency resolution, meanwhile there are two others alternatives, using gdebi, or the apt-get tool. To use the later just use:

sudo apt-get install /path/to/package.deb

Even if you are on the directory with the package you need to give a path using ./ at the start:

sudo apt-get install ./package.deb

A handy tip when installing a program like Libreoffice which has multiple .deb files in a folder is to use.

sudo dpkg -i *.deb

Create your own script installer debInstaller as the following:

#!/bin/bash

dpkg -i "$@"

apt-get --yes --fix-broken install

Make the script executable with

chmod +x debInstaller

Then move it to some dirs in your PATH or add the current directory to your PATH.

I'm going to move it to /usr/bin

sudo cp debInstaller /usr/bin

Now you can install any .deb package using the command:

sudo debInstaller some-package.deb

The added value of this method is the solving the dependencies problem, since mostly you'll face some problems when you install a .deb with dpkg -i due to dependencies error, so you have to use apt-get install -f to solve it, this script will do the job for you, but here I used apt-get --yes --fix-broken install to automatically solve these errors without user intervention.

The gdebi command-line solution

Here's the best way to install a .deb file on Ubuntu on the command-line:

sudo gdebi skype.deb

If you don't have gdebi installed already, install it using sudo apt install gdebi-core.

Why gdebi?

gdebi will look for all the dependencies of the .deb file, and will install them before attempting to install the .deb file. I find this much preferable than sudo dpkg -i skype.deb && sudo apt install -f. The latter is much too eager to remove dependencies in certain situations. For instance, when I tried to install Skype, it attempted to remove 96 (!) packages, including packages like compiz and unity! gdebi gave a much clearer error message:

$ sudo gdebi skype.deb

Cannot install 'libqtgui:i386'

(Here is the solution to that particular issue, by the way.)

To install deb files, open Terminal and type:

sudo dpkg -i file.deb

sudo apt-get install -f

sudo dpkg -i file.deb   

The second line is to fix broken packages if the installation fails, then, install again to complete the installation.

Another approach is to use gdebi tool to install deb files.