-prefix /opt/qt-&qt-version; : This command sets up the install destination. -qt-gif : This command adds support for gif files to the libraries. -system-libpng -system-libmng -system-zlib -system-libjpeg : This command forces the library to use the shared libraries that are on your system instead of recreating its own set of support libraries for these functions. -no-g++-exceptions : This command disables the exceptions coding generated by the C++ compiler. -thread : This command compiles the library to support multi-threading. if test -L /opt/qt; then rm /opt/qt; fi : This command eliminates the link if it already exists so our next command runs properly. ln -s /opt/qt-&qt-version; /opt/qt : This command standardizes the location of the qt libraries to the ld.so.conf entry described below. cp -r doc/man /opt/qt/doc : This command installs the man directory which is missed by make install. cp -r examples /opt/qt/doc : This command installs the examples directory which is missed by make install.