Auto-update Minecraft server

mc_update.sh

#/bin/bash


# Instructions: place in /srv/minecraft-server
#               cron to check every 4 hours:
#                   0 */4 * * * /src/minecraft-server/mc_update.sh


cd $(dirname $0)

MANIFEST_URL=https://launchermeta.mojang.com/mc/game/version_manifest.json
MANIFEST_DATA=`curl --silent $MANIFEST_URL`
VERSION=`echo $MANIFEST_DATA | jq -r .latest.release`
VERSION_URL=`echo $MANIFEST_DATA | jq -r '.latest.release as $latest | .versions | .[] | select(.id == $latest) | .url'`
echo "Latest version: $VERSION"

VERSION_DATA=`curl --silent $VERSION_URL | jq .downloads.server`
SHA=`echo $VERSION_DATA | jq -r .sha1`
URL=`echo $VERSION_DATA | jq -r .url`

FILENAME="minecraft_server_$VERSION.jar"
if [ -f $FILENAME ]; then
	CURRENT_SHA=`sha1sum $FILENAME | awk '{ print $1 }'`
	if [ "$SHA" = "$CURRENT_SHA" ]; then
		echo "Up-to-date"
		exit 0
	else
		echo "Checksum mismatch, redownloading..."
	fi
fi

echo "Downloading from $URL (checksum $SHA)..."

curl --silent $URL > $FILENAME

CURRENT_SHA=`sha1sum $FILENAME | awk '{ print $1 }'`
if [ "$SHA" != "$CURRENT_SHA" ]; then
	echo "Checksum mismatch: $SHA != $CURRENT_SHA"
	exit 1
fi
	
echo "Download complete"

ln -sf $FILENAME "minecraft_server.jar"
echo "(Re)link complete"

service minecraft-server restart