Don't expect any particular casing convention

[mcandre]

While it is good for shell script authors to apply conventions of variable casing to distinguish between local and environment variables, this is unfortunately not a practical rule to use for environment variables in general.

Some applications have already begun to expect lowercase variable names (http_proxy), while other applications expect uppercase names (HTTP_PROXY). I wish a quick transition to a uniform standard would occur, but this has not been the case. So while the designer of a new environment-facing application should by all means prefer uppercase, we cannot reasonably apply a casing rule to .env files, because of the existing, mature exceptions.

Note that both lowercase and uppercase variables may be needed, for applications that need to apply proxy configurations to different sub-application calls. Hence, dotenv-linter should probably neither warn for duplicate variables as long as the declarations differ in casing.

[sobolevn]

Hey, @mcandre! Thanks for your feedback.

This feature is planned for the next major release. I am planning to make an exception mechanism. Something similar to noqa in flake8. This will eliminate the need to reason about lower and uppercases. Just use noqa where you need to use lowercase variables for some reason.

Or disable this check completely via --ignore flag.

By the way, I invite you to collaborate on this feature. I would appreciate some help!

[sobolevn]

I am going to merge it with #31