I prefer using environment variables, and then enforcing this in the Makefile: https://gist.github.com/ChimeraCoder/4728823 https://gist.github.com/ChimeraCoder

I prefer using environment variables, and then enforcing this in the Makefile: https://gist.github.com/ChimeraCoder/4728823 https://gist.github.com/ChimeraCoder/4728823 If this is the first target (or a prerequisite of the first target), then running 'make' will ensure that those variables are set to non-empty strings.