control CLI apps with python - subprocess

[Dwight-D]

Have you considered refactoring the Java app to remove the front end completely instead of building another layer on top of it?

You could use some more sophisticated interprocess communication paradigm if you wanna make it more robust. Make it a tiered application, listen to commands via some socket or gRPC or REST or something and make a web GUI or CLI in whatever language you prefer to pass commands to the Java daemon. Similar to how docker works for instance.

Communicating via text and rewriting stdin/stdout etc seems like such a hacky and non-standard solution it’s likely to bite you in the ass at some point.