/usr/ is in libqt5websockets5-dev 5.7.1~20161021-4.
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..
/usr/include/
/usr/include/x86_64-linux-gnu/
/usr/include/x86_64-linux-gnu/qt5/
/usr/include/x86_64-linux-gnu/qt5/QtWebSockets/
/usr/include/x86_64-linux-gnu/qt5/QtWebSockets/QMaskGenerator
/usr/include/x86_64-linux-gnu/qt5/QtWebSockets/QWebSocket
/usr/include/x86_64-linux-gnu/qt5/QtWebSockets/QWebSocketCorsAuthenticator
/usr/include/x86_64-linux-gnu/qt5/QtWebSockets/QWebSocketServer
/usr/include/x86_64-linux-gnu/qt5/QtWebSockets/QtWebSockets
/usr/include/x86_64-linux-gnu/qt5/QtWebSockets/QtWebSocketsDepends
/usr/include/x86_64-linux-gnu/qt5/QtWebSockets/QtWebSocketsVersion
/usr/include/x86_64-linux-gnu/qt5/QtWebSockets/qmaskgenerator.h
/usr/include/x86_64-linux-gnu/qt5/QtWebSockets/qtwebsocketsversion.h
/usr/include/x86_64-linux-gnu/qt5/QtWebSockets/qwebsocket.h
/usr/include/x86_64-linux-gnu/qt5/QtWebSockets/qwebsocketcorsauthenticator.h
/usr/include/x86_64-linux-gnu/qt5/QtWebSockets/qwebsocketprotocol.h
/usr/include/x86_64-linux-gnu/qt5/QtWebSockets/qwebsockets_global.h
/usr/include/x86_64-linux-gnu/qt5/QtWebSockets/qwebsocketserver.h
/usr/lib/
/usr/lib/x86_64-linux-gnu/
/usr/lib/x86_64-linux-gnu/cmake/
/usr/lib/x86_64-linux-gnu/cmake/Qt5WebSockets/
/usr/lib/x86_64-linux-gnu/cmake/Qt5WebSockets/Qt5WebSocketsConfig.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5WebSockets/Qt5WebSocketsConfigVersion.cmake
/usr/lib/x86_64-linux-gnu/libQt5WebSockets.prl
/usr/lib/x86_64-linux-gnu/pkgconfig/
/usr/lib/x86_64-linux-gnu/pkgconfig/Qt5WebSockets.pc
/usr/lib/x86_64-linux-gnu/qt5/
/usr/lib/x86_64-linux-gnu/qt5/mkspecs/
/usr/lib/x86_64-linux-gnu/qt5/mkspecs/modules/
/usr/lib/x86_64-linux-gnu/qt5/mkspecs/modules/qt_lib_websockets.pri
/usr/share/
/usr/share/doc/
/usr/share/doc/libqt5websockets5-dev/
/usr/share/doc/libqt5websockets5-dev/changelog.Debian.gz
/usr/share/doc/libqt5websockets5-dev/copyright
/usr/lib/x86_64-linux-gnu/libQt5WebSockets.so