simple bash script to show log for a docker image

docker-log.sh

#!/usr/bin/env bash

DOCKER=`which docker`

usage()
{
	echo "Usage: $(basename $0) [-l num] IMAGE"
	exit 0
}

if [ "$#" -lt 1 ]; then
	usage
	exit 0
fi

l="-1"
while getopts ":l:" opt;
do
	case "$opt" in
		l)
			l=$OPTARG
			;;
	esac
done
shift $((OPTIND-1))

for commit in $($DOCKER history $1 | sed 1d | awk '{ print $1 }')
do
	if [ $l -eq 0 ]; then
		exit 0
	elif [ "$commit" == "<missing>" ]; then
		echo "...<missing commit ids>..."
		exit 0
	elif [ $l -gt 0 ]; then
		l=$((l - 1))
	fi
	content="$commit
$($DOCKER inspect $commit | tr -d '\"' | grep 'Created\|Author\|Comment')"
	echo "$content"
done