、makefile文件的作用是什么，makefile文件中有一种变量，其值是根据具体的规则来确定的，称为自动变量，其中代表所有依赖文件列表的是哪个；举例说明make命令的工作流程。-What is the role of, makefile file, there is a variable in the makefile file, its value is based on the specific rules, known as automatic variables, which represent all the list of dependent files which　for example the make command workflow.