This application failed to start because it could not find or load the Qt platform plugin "xcb" in "

使用ldd demo命令查看应用程序的依赖时，可以找到‘xcb’的库，但是依然报：

This application failed to start because it could not find or load the Qt platform plugin "xcb" in "".

参考解决方法：https://askubuntu.com/questions/308128/failed-to-load-platform-plugin-xcb-while-launching-qt5-app-on-linux-without

我的解决方法，执行了该命令：

sudo ln -sf /usr/lib/x86_64-linux-gnu/qt5/plugins/platforms/ /usr/bin/

就可以了，但是真正的原理还不是特别清楚。