Qt 4 and 5 in same machine (Ubuntu)

"qtchooser -list-versions": get available version of qt.

modify following file 

/usr/lib/x86_64-linux-gnu/qtchooser/5.conf

so that it specify directory of qmake and lib of qt. Example for qt5:

/opt/Qt5.5.0/5.5/gcc_64/bin

/opt/Qt5.5.0/5.5/gcc_64

To choose different qt version: 

"export QT_SELECT=5"

To check current using qt:

"qmake -v" 

"export PKG_CONFIG_LIBDIR=/opt/qt-4.8.7/lib:$PKG_CONFIG_LIBDIR"
"export PATH=/opt/qt-4.8.7/bin:$PATH"
"export PKG_CONFIG_PATH=/opt/qt-4.8.7/lib/pkgconfig/:$PKG_CONFIG_PATH"