static String backtickJavax(String javaxargs) ctex {
  File x20file = new File(userHome(), ".javax/x20.jar");
  if (!x20file.isFile()) {
    String url = "http://tinybrain.de/x20.jar";
    byte[] data = loadBinaryPage(url);
    if (data.length < 1000000)
      fail("Could not load " + url);
    saveBinaryFile(x20file.getPath(), data);
  }
  String jarPath = x20file.getPath();
  String cmd = "java -jar " + (isWindows() ? winQuote(jarPath) : bashQuote(jarPath)) + " " + javaxargs;
  print("Running: " + cmd);
  return backtick(cmd);
}