code: func Setsys(key, value string) error {
  	if !_IS_ROOT {
  		return ErrNoRoot
  	}
  	return _Set(_SETTINGS.global, key, value)
  }
docs: // == Set system-wide variables
  // Setsys sets the value of the environment variable named by the key that
  // affects the system as a whole. You must be Root.
  // It returns an error, if any.