How to make someone OP using docker attach

Hello! Excellent work on this project. I have read that rcon-cli is not supported and your workaround was to use docker attach. I added the two lines to my compose file and I'm able to attach to the container but I can't figure out how to issue commands. In rcon-cli I would issue /op to set the operator. How can I do that using docker attach?

Start with the two compose-file lines that enable Docker attach and review how the container accepts commands through docker attach. Document the steps for issuing `/op ` in that session, then verify the instructions against the container setup described in the issue.

Written by the indexing model from the issue text.