Install Docker on ubuntu

Steps:

• on Ubuntu 18.04 / 19.04

$ sudo apt-get install apt-transport-https ca-certificates curl software-properties-common
$ curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
$ sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable edge"
$ sudo apt-get update
$ apt-cache policy docker-ce
$ sudo apt-get install -y docker-ce
$ sudo systemctl status docker

Learn From:

link

Steps:

• on Ubuntu 20.04

sudo apt install docker.io
sudo systemctl enable --now docker
docker --version

Learn From

Use docker by non-root user:

To display all users run following command: 

 $ compgen -u

To display all groups run following command:

$ compgen -g

If there has no group docker, you can add it first:

$ sudo groupadd docker

Then add user to docker group:

$ sudo usermod -aG docker [non-root user] 

Restart or re logon to activate this setting.