docs: private String escapeAndJoin(String[] commandline) {
      // TODO: we should try to escape special characters here, depending on the OS.
      StringBuilder b = new StringBuilder();
      Pattern specials = Pattern.compile("[\\ ]");
      for (String arg : commandline) {
        if (b.length() > 0) {
          b.append(" ");
        }
  
        if (specials.matcher(arg).find()) {
          b.append('"').append(arg).append('"');
        } else {
          b.append(arg);
        }
      }
      return b.toString();
    }