/*
  * Untar the given file in the output directory.
  */
 private void untar(String message, File file) {
   String name = file.getName();
   File gzFile = new File(output, name);
   output.mkdirs();
   run(message, new String[] {"cp", file.getAbsolutePath(), gzFile.getAbsolutePath()});
   run(message, new String[] {"tar", "-zpxf", gzFile.getAbsolutePath()});
   gzFile.delete();
 }
 /*
  * Delete the link file with the given name from the links folder.
  */
 public void removeLinkFile(String message, String filename) {
   File file = new File(output, getRootFolder() + "links/" + filename + ".link");
   file.delete();
 }