As we said earlier, qmake is the foundation of the Qt framework compilation system. In Qt Creator, when you click on the Build button, qmake is invoked. Let's study what qmake is exactly doing by calling it ourselves on the CLI (Command Line Interface).

Create a temporary directory where you will store the generated files. We are working on a Linux box, but this is transposable on any OS. We chose /tmp/sysinfo. Using the CLI, navigate to this new directory and execute the following command:

/path/to/qt/installation/5.7/gcc_64/bin/qmake -makefile -o Makefile /path/to/sysinfoproject/ch02-sysinfo.pro

This command will execute qmake in the -makefile mode to generate a Makefile based on your sysinfo.pro file. If you skim through the Makefile content, you will see many things we covered earlier in the .pro section. The link to Qt modules, headers of different modules, inclusion of the headers and sources files of your project, and so on.

Now, let's build this Makefile by...