code: func unitPrintf(s string, nu unit.UnitNameInfo) (out string) {
  	out = strings.Replace(s, "%n", nu.FullName, -1)
  	out = strings.Replace(out, "%N", nu.Name, -1)
  	out = strings.Replace(out, "%p", nu.Prefix, -1)
  	out = strings.Replace(out, "%i", nu.Instance, -1)
  	return
  }
docs: // unitPrintf is analogous to systemd's `unit_name_printf`. It will take the
  // given string and replace the following specifiers with the values from the
  // provided UnitNameInfo:
  // 	%n: the full name of the unit               (foo@bar.waldo)
  // 	%N: the name of the unit without the suffix (foo@bar)
  // 	%p: the prefix                              (foo)
  // 	%i: the instance                            (bar)