SecurityManager sm = Runtime.securityManager;
SecurityManager sm = SecurityManager.current;
  public static String getenv(String name)  {    if (name == null)      throw new NullPointerException();    SecurityManager sm = Runtime.securityManager; // Be thread-safe.    if (sm != null)      sm.checkPermission(new RuntimePermission("getenv." + name));    return VMSystem.getenv(name);    }