Minecraft Server Upgrade Skript

#!/bin/bash
newest_server_version=$(curl https://minecraft.net/en-us/download/server | grep https://s3.amazonaws.com/Minecraft.Download/versions/.*/minecraft_server.*.jar | cut -d '/' -f6)
in_use_server_version=$(cat /opt/minecraft/logs/latest.log | grep "server version" | cut -d ' ' -f8)

echo $in_use_server_version
echo $newest_server_version

if [ $in_use_server_version == $newest_server_version ]; then
echo "Server is up to date!"
fi

if [ $in_use_server_version != $newest_server_version ]; then
        echo "SERVER NEEDS UPDATE!"
        new_server_download_link=$(curl https://minecraft.net/en-us/download/server | grep https://s3.amazonaws.com/Minecraft.Download/versions/.*/minecraft_server.*.jar | cut -d '"' -f2)

        cd /opt/minecraft
        #Make Backup of Server
        cp minecraft_server.jar minecraft_server.jar-backup
        cp -r world world-backup

        #Stop Minecraft Server
        server_session=$(screen -ls | grep minecraftd)
        #screen -X -S 718.minecraftd quit

        wget -O minecraft_server.jar $new_server_download_link
        chmod +x /opt/minecraft/minecraft_server.jar
        /opt/minecraft/./start_server.sh
fi