The default _docker images_ will show all top level images, their repository and tags, and their size.
### Load an image in docker
`$ docker load -i ubuntu-14.04.tar`
- **i** - Read from tar archive file, instead of STDIN
It loads an image or repository from a tar archive (even if compressed with gzip, bzip2, or xz) from a file or STDIN. It restores both images and tags.
- When an operator executes `docker run`, the container process that runs is isolated in that it has its own file system, its own networking, and its own isolated process tree separate from the host.
### Run or start a new OS
`$ docker run -it ubuntu:14.04`
- The `docker run` command first `creates` a writeable container layer over the specified image, and then `starts` it using the specified command.
- The above example runs a container using the `ubuntu:14.04` image. The `-it` instructs Docker to allocate a pseudo-TTY connected to the container’s stdin; creating an interactive `bash` shell in the container.
### See all the running OSs
`$ docker ps`
- The `docker ps` command only shows running containers by default.
- To see all containers, use the `-a` (or `--all`) flag:
`$ docker ps -a`
### Come out from docker OS console
`exit`
### From shell of docker OS, for coming out without exiting container
press _ctrl + p + q_
### From terminal of base system, to run a command in docker OS
`$ docker exec mycontainer ifconfig`
- **mycontainer** is the name of container.
- The `docker exec` command runs a new command in a running container.