Remove Docker image where tag is <none>

remove_docker_images_by_tag.sh

#!/bin/env bash

# Use: remove docker images where tag is "<none>"

# uses unix pipes
# command parts explained:

# docker images : list all of the images in Docker. Each line looks like: 
#    "maven  3.6.3-adoptopenjdk-11   b6e818035058   10 days ago   540MB"

# grep "<none>": show only lines that contain string <none>. Could be any string on the line.

# awk '{print $3}' : use the text processor 'awk' to split each line into columns using 
#    spaces and print the third colum (the docker image id, like 'b6e818035058' above)

# xargs docker image rm : use the xargs app to pass the result into the command 'docker image rm <piped value>'.
#    Converts to 'docker image rm b6e818035058'

docker images | grep "<none>" | awk '{print $3}' | xargs docker image rm