> Environment variables are good for long-term, multi-program configurations Not just that. They're also useful for when a program is called by another program

> Environment variables are good for long-term, multi-program configurations Not just that. They're also useful for when a program is called by another program and you want to control something about its invocation without having to modify the source code of that other program each time. For example, I might use a different value for LESS when calling man than when calling git.