In Linux, I would like to place rcon in /usr/local/bin and call it as a comand, but it throws an error when the rcon.yaml file is missing in the current directory.

Here is my suggestion: allow rcon.yaml to be optional if not found. When searching for rcon.yaml, I recommend that it first searches the current folder. If not found, it should then search the user's home folder. If still not found, it should proceed to search the /etc folder. If not found in any of these locations, the rcon.yaml file can be skipped.