Command to remove all unused images

I like to use this script from Spotify: GitHub - spotify/docker-gc: INACTIVE: Docker garbage collection of containers and images

From the README:

A simple Docker container and image garbage collection script.

  • Containers that exited more than an hour ago are removed.
  • Images that don’t belong to any remaining container after that are removed.

Although docker normally prevents removal of images that are in use by containers, we take extra care to not remove any image tags (e.g., ubuntu:14.04, busybox, etc) that are in use by containers. A naive docker rmi $(docker images -q) will leave images stripped of all tags, forcing docker to re-pull the repositories when starting new containers even though the images themselves are still on disk.