code: public static void link(File source, File target) throws IOException {
          if( UtilJNI.ON_WINDOWS == 1 ) {
              if( UtilJNI.CreateHardLinkW(target.getCanonicalPath(), source.getCanonicalPath(), 0) == 0) {
                  throw new IOException("link failed");
              }
          } else {
              if( UtilJNI.link(source.getCanonicalPath(), target.getCanonicalPath()) != 0 ) {
                  throw new IOException("link failed: "+strerror());
              }
          }
      }
docs: Creates a hard link from source to target.
  @param source
  @param target
  @return