I'm not confident enough to say this for sure, but I think you are off base.

I created a demo in the Rust playground [0] which shows that there is no implicit environment variable expansion. Also, the source for `std::process:Command` [1] looks to be calling into libc to perform a fork/exec.

That said, this is rather new territory for me, so let me know if I'm missing something here.

[0] : https://play.rust-lang.org/?version=stable&mode=debug&editio... [1] : https://github.com/rust-lang/rust/blob/master/src/libstd/sys...