Correct Pull: Fixes Issue #3400

Hi! Sorry about the last pull, something went weird, probably my fault.

This still needs work regards to documentation, and I'm sure refactoring, but if appropriate I'd like to start the discussion regarding the added command (param) and its functionality: setting a required value when running a container, which would then be passed into the container as an environment variable.

Let me know if you have any questions, thank you!