如何使用makefile生成自动头文件

I am working on a project which has a large source code. I want to create a header file which includes specific environment variables using makefile while the project is being compiled because the project has different types. I want to use header file anywhere in the project because I don't want to include some code snippets or vice versa while project is being compiled. How can I do it?I am working on a project which has a large sou