title: I upgrade mac os 10.6 to 10.9.4 , gcc can not work ,can anyone help me?
body: <p>compile error like this:</p>
  
  <p>fatal error : 'sys/types.h' file not found .</p>
  
  <p>and a test application with main function,error like this:</p>
  
  <p>error : unkonwn type name '__darwin_off_t'</p>
  
  <p>ps : I hace installed the xcode command tool ..</p>