This is documented:

http://doc.qt.io/qt-5/cmake-manual.html

The easiest way to use CMake is to set the CMAKE_PREFIX_PATH 
environment variable to the install prefix of Qt 5

做这个

export CMAKE_PREFIX_PATH=/home/user/Programs/<other_stuff>

其中引用编译器等，以使此完整路径有效：

where references the compiler etc, so that this complete path is valid:

/home/user/Programs/<other_stuff>/bin/qmake*