Where / How does the Mix environment variable get set?

[hubertlepicki]

https://github.com/elixir-lang/elixir/blob/50293b46f13a86328f0ffabdcbb8592e29ac24c6/lib/mix/lib/mix/state.ex#L11

it gets set here. It’s a compile-time variable, gets fetched fron shell environment, and default value is “dev”.