How to install & use nano in a running Docker container

If you want to interactively edit a file in a docker container, you might want to install an editor like GNU nano (for example to debug your config files) in your Docker container that allows you direct access to the container’s file system.

docker exec -it [container name or ID] bash -c 'apt-get -y update && apt -y install nano'

This will work for most debian/Ubuntu-based containers ; for other containers you might need to use a package manager other than apt

Now you can use docker exec -it to interactively edit a config file, e.g.:

docker exec -it [container name or ID] nano /etc/host.conf