Installing Qt is usually an easy task, yet it can be frustrating if you try to install it on Linux. I use Unumtu 12.04 LTS running on a Parallels VM to explain the process, yet is should be applicable to almost any Linuy distribution.
Background - What do you need?
The Qt framework, e.g. the Qt Creator, all libraries and everything needed in relation to Qt
Qt uses OpenGL to render GUI elements. It isn't included with the Qt installation package and needs to be installed via apt-get
GNU g++ compiler
The GNU g++ compiler isn't included with the Qt installation package, either. You can use another compiler (GPP for example), but g++ is recommended by digia.
Before you start, it is recommended to run
sudo apt-get update && sudo apt-get upgrade
sudo apt-get autoremove
on your Terminal in order to ensure that your system is up-to-date and doesn't contain any obsolete or outdated packages.
After this, get the Qt installation package from the Digia download page. Before you can run it, you need to adjust the permissions on the downloaded file:
chmod +x /home/parallels/Downloads/qt-opensource-linux-x64-5.2.1.run
chmod +x adds the permission to run the file as executable for anyone on the computer, meaning that anyone can use the file to install Qt. After you have done that, you need to execute the file in order to install Qt.
Congratulations, you have installed Qt - But there is still more than just something missing. For example, you can't compile anything yet. To install g++, type
sudo apt-get install build-essential
in your Terminal. This will install the g++ compiler (and generally development related stuff) - You don't need to adjust anything with your Qt Creator settings, it will automatically detect the newly installed compiler the next time you start it.
In order to install OpenGL you need to run
sudo apt-get install mesa-common-dev
sudo apt-get install libcr-dev
sudo apt-get install libglu1-mesa-dev -y
from your Terminal. The first command installs OpenGL while the second two command install some development-related additional OpenGL libraries which aren't required for non-development related activities, but needed to build Qt source code which is using OpenGL features.
If you plan on using any SSL encryption (KQOAuth for example requires this), make sure to install the libressl development package:
sudo apt-get libssl-dev