Qt Project to MakeFile

qmake -spec macx-g++ x.pro on Mac OS X to generate Makefile
qmake x.pro on linux to generate Makefile (default behaviour)
qmake -spec win32-g++ x.pro on Windows to generate Makefile

References:
[1] https://stackoverflow.com/questions/8571687/how-to-get-a-makefile-from-qmake