Today Docker Version 1.3 is was released and is avalable in repositories.
$docker info Containers: 63 Images: 356 Storage Driver: aufs Root Dir: /var/lib/docker/aufs Dirs: 482 Execution Driver: native-0.2 Kernel Version: 3.1.0-1-amd64 Operating System: Debian GNU/Linux 7 (wheezy)
It introduces new command exec. It makes tools like nsinit and nsenter obsolete. Entering running container becomes possible with Docker itself and i like this very, very much. Docker's exec command allows to execute additional process within the container, e.g.
docker exec myContainer -it bash
Example above attaches to running container "myContainer".
Another new interesting command is docker create
docker create #creates container out of image like docker run, but without running it. So docker run some/image
it is the same like
$CONTAINER_ID=$(docker create -t -i ubuntu bash) docker start -a -i $CONTAINER_ID