How to Install DEB package with All Necessary Dependencies Automatically

When you are installing .deb packages with dpkg -i command, it does not automatically install necessary dependencies. For example, when I was trying to install Dropbox client on my freshly installed Ubuntu, I get
$ sudo dpkg -i dropbox_2015.10.28_amd64.deb 
Selecting previously unselected package dropbox.
(Reading database ... 211659 files and directories currently installed.)
Preparing to unpack dropbox_2015.10.28_amd64.deb ...
Unpacking dropbox (2015.10.28) ...
dpkg: dependency problems prevent configuration of dropbox:
 dropbox depends on python-gtk2 (>= 2.12); however:
  Package python-gtk2 is not installed.

dpkg: error processing package dropbox (--install):
 dependency problems - leaving unconfigured
Processing triggers for gnome-menus (3.13.3-6ubuntu3.1) ...
Processing triggers for desktop-file-utils (0.22-1ubuntu5) ...
Processing triggers for bamfdaemon (0.5.3~bzr0+16.04.20160701-0ubuntu1) ...
Rebuilding /usr/share/applications/bamf-2.index...
Processing triggers for mime-support (3.59ubuntu1) ...
Processing triggers for hicolor-icon-theme (0.15-0ubuntu1) ...
Processing triggers for man-db (2.7.5-1) ...
Errors were encountered while processing:
 dropbox

This is quite annoying. One solution is to remove Dropbox and install dependency first and re-install Dropbox. This process is outlined here for Google Chrome installation, but the same holds for any other .deb packages.

Well, it turns out that there is a good utility that will do this for you automatically. Try this!

$ sudo apt-get install -y gdebi

...

$ sudo gdebi dropbox_2015.10.28_amd64.deb Reading package lists... Done

Building dependency tree        

Reading state information... Done

Reading state information... Done

Requires the installation of the following packages: python-gtk2 

cloud synchronization engine - CLI and Nautilus extension

 Dropbox is a free service that lets you bring your photos, docs, and videos

 anywhere and share them easily.

 .

 This package provides a command-line tool and a Nautilus extension that

 integrates the Dropbox web service with your GNOME Desktop.

Do you want to install the software package? [y/N]:y

Fetched 0 B in 0s (0 B/s)                                            

Selecting previously unselected package python-gtk2.

(Reading database ... 218142 files and directories currently installed.)

Preparing to unpack .../python-gtk2_2.24.0-4ubuntu1_amd64.deb ...

Unpacking python-gtk2 (2.24.0-4ubuntu1) ...

Setting up python-gtk2 (2.24.0-4ubuntu1) ...

Selecting previously unselected package dropbox.

(Reading database ... 218162 files and directories currently installed.)

Preparing to unpack dropbox_2015.10.28_amd64.deb ...

Unpacking dropbox (2015.10.28) ...

Setting up dropbox (2015.10.28) ...

Please restart all running instances of Nautilus, or you will experience problems. i.e. nautilus --quit

Dropbox installation successfully completed! You can start Dropbox from your applications menu.

Processing triggers for gnome-menus (3.13.3-6ubuntu3.1) ...

Processing triggers for desktop-file-utils (0.22-1ubuntu5) ...

Processing triggers for bamfdaemon (0.5.3~bzr0+16.04.20160701-0ubuntu1) ...

Rebuilding /usr/share/applications/bamf-2.index...

Processing triggers for mime-support (3.59ubuntu1) ...

Processing triggers for hicolor-icon-theme (0.15-0ubuntu1) ...

Processing triggers for man-db (2.7.5-1) ...

Much easier, right?