How can you change settings or update an application inside an already running Docker container?

It is not recommended to modify settings or update an application directly inside an already running Docker container, as containers are considered immutable units. However, if you need to make changes without stopping the container, you can:

• Connect to the container using docker exec -it <container_id> /bin/bash and manually modify files or settings. But these changes will be lost when the container is restarted.
• For permanent changes, it is better to update the Dockerfile or the application's source files, build a new image, and run a new container based on it.

Thus, the correct approach is to update the image and restart the container, rather than changing something inside a running container.