3写Makefile

文件名就写Makefile

使用不标准的文件名作为Makefile文件,则使用-f指定Makefile文件

如果make命令没有找到Makefile文件,这时必须指定一个goal(target)
make将尝试使用内置的隐式规则去构建它

include#暂停当前makefile,读取其他makefile,就理解为C语言中的#include

The include directive tells make to suspend reading the current makefile and read one or more other
makefiles before continuing.

#变量赋值
immediate = deferred
immediate ?= deferred
immediate := immediate
immediate ::= immediate
immediate :::= immediate-with-escape
immediate += deferred or immediate
immediate != immediate