M4 宏编程 | 语法规则、宏替换、流程控制、嵌套求值、引号用法及示例注：本文为 “M4 宏编程” 相关合辑。 英文引文，机翻未校。 如有内容异常，请看原文。m4 is a macro processor for the COHERENT system. It is a powerful and flexible text processing tool. You can tell it, with a great degree of generality, to search for macro names and replace them with other stri