RUN # run instruction executed by docker server, create intermediate containerД¬MD # create intermediate, specify image should execute(primary command) when it is created as a container docker build. Sh/shell: command processor (command prompt), like bash Docker image Getting a Command Prompt in a Container docker exec -it sh t: show the text output prettier/terminal docker exec -it # -a: print out outputs from container docker system prune #delete containersДocker stop #SIGTERM, shut down at its own time, clean up, save files SELinux: protect host machine (what makes the containers consistent)Дocker run = create a container (hard drive FS snapshot) + start a container (start command) docker create hello-world.Control groups: restrictions on the amount of system resources processes might use.Namespaces: isolate process to resources inside a namespace.Docker containers are considered suitable to run multiple applications over a single OS kernel whereas, virtual machines are needed if the applications or services required to run on different OS.

Sharing the host OS between containers makes them light and increases the boot time. In contrast, Docker containers host on a single physical server with a host OS, which shares among them.

Guest OS can be any OS, like Linux or Windows, irrespective of host OS. Virtual machines have host OS and the guest OS inside each VM. Fewer hardware resources and quick to start and terminate. A set of one or more processes that are isolated from the rest of the system, but still have the resources it needs. Image: a single file with all the dependencies and config required to run a program, A Docker imageВ includes the elements needed to run an application as a containerВ - such as code, config files, environment variables, libraries and run time.Д¬ontainer: Instance of an image.

Docker run image with multiple port