Copy files from container to host

docker cp <container_id>:/path/to/original/file/filename.ext /path/to/save/to/new_filename.ext

Example: docker cp ~/Downloads/views-7.x-3.14.tar.gz 13a562293114:/var/www/docroot/sites/all/modules/views-7.x-3.14.tar.gz

Copy files from host to container

docker cp /path/to/original/file/filename.ext <container_id>:/path/to/save/file/to/new_filename.ext

Alternative for copying files from host to container

cat /local/file/path | docker exec -i <running-container-id> sh -c 'cat > /inside/docker/file/path'