cross-dotenv is an unholy alliance of:

• cross-env (for it's cross-platform inline definition of environment variables),
• dotenv (for it's loading of environment variables from a .env file), and
• cross-var (for it's cross-platform substition of environment variables (via copying and pasting code)).

Funnily enough, none of these projects alone seem to do all of this.

• Environment variable substitution is unreliable with cross-env
• dotenv really just loads the .env file
• run.env doesn't work on windows.
• cross-var doesn't allow inline definition of environment variables.