-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. ln -sf /opt/qt-&qt-version; /opt/qt: This command standardizes the location of the qt libraries to the ld.so.conf entry described below.