ubuntu@ubuntuserver:~$ sudo systemctl daemon-reload 
ubuntu@ubuntuserver:~$ sudo systemctl restart docker
ubuntu@ubuntuserver:~$ sudo systemctl status docker
ubuntu@ubuntuserver:~$ docker pull hello-world
Using default tag: latest
latest: Pulling from library/hello-world
5b0f327be733: Pull complete
Digest: sha256:07d5f7800dfe37b8c2196c7b1c524c33808ce2e0f74e7aa00e603295ca9a0972
Status: Downloaded newer image for hello-world:latest
ubuntu@ubuntuserver:~$ docker run hello-world
Hello from Docker!
This message shows that your installation appears to be working correctly.