# Docker Running containers

**Running** a container starts an instance from an image. Use `docker run <image>` to start; add `-it` for interactive (attach a terminal), `-d` to run in background, `--name <name>` to give it a name. The container stops when its main process exits.

```bash
$ docker run -it ubuntu bash            # interactive, exit to stop
$ docker run -d --name web nginx        # background, stays until stopped
$ docker run -e VAR=value myapp         # set environment variables
$ docker run -p 8080:80 myapp           # map ports (host:container)
$ docker run -v /host:/container myapp  # mount a volume
```

Flags stack: `docker run -it -d --name foo -e X=1 -p 8080:80 image`. Use `docker ps` to list running containers, `docker logs` to see output, and `docker exec` to run commands inside. Stopping a container with `docker stop` sends SIGTERM; it waits briefly, then sends SIGKILL.