title: after uninstall protobuf, use protoc command, there still protoc :error while loading shared libraries: libprotoc.so.12
body: <p>I installed protobuf 3.2.0 from the source code in Ubuntu;
  but now I　want to install a lower  version's protobuf , so I　use make uninstall </p>
  
  <p>Then I verify if  protobuf is still in my computer, so I use protoc command;</p>
  
  <p>the response is : 
  protoc: error while loading shared libraries: libprotoc.so.12: cannot open shared object file: No such file or directory</p>
  
  <p>Why after I　uninstall protobuf, there still this error message？ How can I　solve this？</p>