Some Basic Docker Commands Beginner Should Know

Docker is a container-based application framework that allows deploying programs that are run as containers. Docker Containers are generally used in CI/CD (Continuous Integration/Continuous Deployment) platform. There are several docker commands you must know when working with Docker.

Useful Articles:

• WHAT IS DOCKER & DOCKER CONTAINER ?
• HOW TO INSTALL DOCKER ENGINE ON UBUNTU 19.10/18.04
• HOW TO INSTALL DOCKER ENGINE ON CENTOS/RHEL 8
• HOW TO INSTALL DOCKER ON UBUNTU 18.04 & 16.04 LTS
• HOW TO INSTALL DOCKER CE ON CENTOS/RHEL 7/6
• WHAT IS DOCKERFILE AND BASICS OF DOCKERFILE
• INSTALLATION OF DOCKER FAILS ON CENTOS 8 WITH ERROR – PACKAGE CONTAINERD.IO-1.2.10-3.2.EL7.X86_64 IS EXCLUDED

In this tutorial, we will help you to understand some basic Docker commands.

Search Docker Images

We can search the Docker images in Docker Hub. Let’s assume you want to find CentOS images.

# docker search centos

Download Docker Container Images

Once you find the image you can pull the image to the local system from Docker hub. Docker pull is almost the same as git pull.

# docker pull centos

Using default tag: latest
latest: Pulling from library/centos
8a29a15cefae: Pull complete
Digest: sha256:fe8d824220415eed5477b63addf40fb06c3b049404242b31982106ac204f6700
Status: Downloaded newer image for centos:latest
docker.io/library/centos:latest

View all Downloaded Docker Container Images

Whenever we download the docker images in your local system using pull command and it saves the docker image locally at /var/lib/docker location. To list all the docker images pulled on the system use following command.

# docker images

REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
ubuntu              latest              1d622ef86b13        12 days ago         73.9MB
nginx               latest              602e111c06b6        12 days ago         127MB
httpd               latest              b2c2ab6dcf2e        12 days ago         166MB
centos              latest              470671670cac        3 months ago        237MB
hello-world         latest              bf756fb1ae65        4 months ago        13.3kB
docker/whalesay     latest              6b362a9f73eb        4 years ago         247MB

Run a Docker Container

Use the following command to run the downloaded Docker image.

# docker run –it centos

-it: It will open a shell that can be used to interact with the container.

Run a Docker Container in Detach Mode

We can launch a container in detached mode using –d option using the following command.

# docker run –d centos

List Container

We can list all the running containers using the following command.

# docker ps

List Container including Shutdown State

To List all the containers including shutdown using the following command.

# docker ps -a

Getting Container Console

If Docker container is running in detach mode and need to take the console of the container using the following command.

# docker attach priceless_austin

Start, Stop, Restart and Kill Containers

We can start, stop and restart docker containers.

Start the container using mention command.

# docker start priceless_austin

Stop the container using mention command.

# docker stop priceless_austin

Restart the container using mention command.

# docker restart priceless_austin

Kill the container using mention command.

# docker kill priceless_austin

Delete/Remove Containers

Remove the Docker containers using the container id or container name. Containers will only remove when docker is in a stopped state.

# docker rm 0fb1de712c0d

To remove a running container forcefully, use ‘-f’ option

# docker rm -f f529d03c4692

Delete/Remove Docker Containers Images

Not like containers you can remove the container images also. You can use image name and id to remove the images. Use the mentioned command to remove the container images.

# docker rmi nginx

Display History of Docker Image

History of Docker command will display the list of commands used while building docker images.

# docker history httpd

Containers resource usage statistics

Display CPU, memory, and network I/O usage of all the containers using the following command. Below command will live to show live streaming of resource usage.

# docker stats

Display statistics without live streaming.

# docker stats --no-stream

Reference: https://docs.docker.com/engine/reference/commandline/docker/

Enjoy it!