Some useful Docker Commands

After installing Docker on your system, to check the installation, you can run the following command:

Input

`$ docker --version`

Output

`Docker version 18.09.6, build 481bc77`

Instead of finding docker images through the DockerHub website on your browser, you can use docker search in the command line. This command returns the specific information, including image name, description, and official stars.

To pull an image from the DockerHub, you can run the docker pull command.

Input

docker pull ubuntu

The tags are used to identify the images inside the Docker hub. If you do not specify a tag, it will use the :latest tag by default. To use an older version of Ubuntu, for example 20.04, you should run the following command:

Input

docker pull ubuntu:20.04

Once the image is downloaded, the docker run command is utilized to generate a container based on the image. To keep the container running when you exit the terminal session, the container should be started in a detached mode. This is like running a process in the background.

Input

docker run -d ubuntu

Usually the output of docker run command shows the container ID and container name as well as any output generated by the container or error messages.

To list all the running containers on a Docker host, run the following command:

Input

`docker ps`

Output

CONTAINER ID   IMAGE           COMMAND                  CREATED          STATUS          PORTS     NAMES
de11dedbd972   ubuntu:latest   "/bin/sh -c 'echo Co…"   14 minutes ago   Up 14 minutes              naughty_faraday

This command will display a table with information about the active containers, including their container ID, image name, status (running, stopped, etc.), creation time, and port mappings. By default, docker ps only shows the running containers. If you want to see all containers (including the ones that have exited), you can use the docker ps -a command.

When you run a Docker container, it will continue to run until it completes its execution or until it is explicitly stopper or terminated. docker stop command stops a container peacefully while docker kill immediately kills its execution.

Downloading images and running containers can quickly fill up disk space. docker rmi followed by the images id is used to remove the image while docker rm followed by container name or id is used to remove containers.