cp, update, rename, stats

Operating on Live Containers

docker cp - move files in and out of a container (running or stopped):

$ docker cp reports:/var/reports/q2.csv ./backup/   # container → host
$ docker cp ./config.ini reports:/etc/app/          # host → container

docker update - change resource limits and restart policy without recreating:

$ docker update --memory 256m --memory-swap 256m --restart unless-stopped worker

docker rename - fix a bad name with zero downtime: docker rename old new.

docker stats - live per-container CPU/memory/net/IO (add --no-stream for scripts):

NAME       CPU %   MEM USAGE / LIMIT   MEM %   NET I/O       PIDS
api        2.3%    89MiB / 256MiB      34.8%   1.2MB/450kB   12
worker     98.7%   201MiB / 256MiB     78.5%   0B/0B         48   ← trouble

Note: Know what update cannot change: image, command, env vars, ports, mounts. Those are immutable per container - changing them means recreate. This boundary (update vs recreate) is a favorite interview question because it's daily operational reality.

Goal: The Fix It Live and Copy In, Copy Out labs drill exactly these - including proving the container was never recreated.