error while loading shared libraries: libopencv_core.so.3.4: cannot open 报错解决方法

报错：

build_release/tools/caffe: error while loading shared libraries: libopencv_core.so.3.4: cannot open shared object file: No such file or directory
Makefile:542: recipe for target 'runtest' failed
make: *** [runtest] Error 127

可烦人了，就说找不到，改了路径之后依旧报错，这时候发现，只需要执行一个命令即可，make runtest 成功。

解决方法：

sudo apt install ffmpeg

然后再继续sudo make runtest