#!/bin/bash
function usage() {
cat << HELP

dockertags  --  list all tags for a Docker image on a remote registry.

EXAMPLE: 
    - list all tags for ubuntu:
       dockertags ubuntu

    - list all php tags containing apache:
       dockertags php apache

HELP
}

if [ # -lt 1 ]; then
    usage
    exit
fi

image="1"
tags=`wget -q https://registry.hub.docker.com/v1/repositories/{image}/tags -O -  | sed -e 's/[][]//g' -e 's/"//g' -e 's/ //g' | tr '}' '\n'  | awk -F: '{print3}'`

if [ -n "2" ]; then
    tags=` echo "{tags}" | grep "2" `
fi
echo "{tags}"