Docker container states

Every application we've run so far was supposed to do some work and stop—for example, we've printed Hello from Docker! and exited. There are, however, applications that should run continuously, such as services.

To run a container in the background, we can use the -d (--detach) option. Let's try it with the ubuntu image, as follows:

$ docker run -d -t ubuntu:20.04

This command started the Ubuntu container but did not attach the console to it. We can see that it's running by using the following command:

$ docker ps
CONTAINER ID   IMAGE           COMMAND       STATUS         PORTS 
NAMES
95f29bfbaadc   ubuntu:20.04    "/bin/bash"   Up 5 seconds kickass_stonebraker

This command...