For every Qt project there is a *.pro file in the project directory that describes the project to qmake. The file takes its name from the project directory.

The project's {directory-name}.pro file is typically created once in a project's lifetime and then edited to reflect configuration options, the addition of code files, etc.

To create a {directory-name}.pro file in a project directory, run

qmake -project

in a terminal shell. If there are any source or other project files in the directory when the above is run, those files will be automatically included in {directory-name}.pro.

Running qmake -project when there is at least a main.cpp (or similar) file will greatly simplify future modifications. Here is a virgin *.pro file for a directory that has main.cpp in it (where main.cpp is a Qt application):

######################################################################
# Automatically generated by qmake (2.01a) Tue Dec 7 17:15:59 2010
######################################################################
 
TEMPLATE = app
TARGET = 
DEPENDPATH += .
INCLUDEPATH += .
 
# Input
SOURCES += main.cpp

In contrast, here is a virgin *.pro file in a virgin (empty) directory:

######################################################################
# Automatically generated by qmake (2.01a) Tue Dec 7 17:07:32 2010
######################################################################
 
TEMPLATE = subdirs
 
# Directories

In Unix (including Linux and OS X) you can explicitly specify debug and release build options:

CONFIG += debug_and_release

debug only:

CONFIG += debug

or release only:

CONFIG += release

These options will cause additional Makefiles to be made. If you do not specify an option in Unix, you will get a debug build (assuming the debug versions of Qt libraries are installed).

I have not yet tested Windows, but the above config option is supposedly not needed and/or invalid in Windows.

To add the files {YourClass}.h and {YourClass}.cpp to your project, replace

SOURCES += main.cpp

with

SOURCES = main.cpp \
          {YourClass}.cpp
HEADERS = {YourClass}.h          

For a resource to be compiled into the binary the *.qrc file must be mentioned in the .pro file:

RESOURCES = foo.qrc

The QtCore and QtGUI libraries are included in all projects by default. To add additional Qt libraries to your project, include:

QT += {libname1} {libname2} ... {libnameN}

to remove:

QT -= {libname1}

where {libnameX} is one of: network, opengl, sql, xml, support. (Note: this list may not be complete as new libraries may have been added since this was written.)

The above names correspond to the QtNetwork, QtOpenGL, QtSQL, QtXML, and QtAssistantClient+Qt3Support libraries.

http://doc.qt.nokia.com/qmake-project-files.html