1. install screen and java-jre-headless
2. create unpriviliged user+group "minecraft"
3. copy unit-file to /lib/systemd/system/minecraft.service
4. enable unit-file
5. copy update-minecraft.sh to /usr/local/bin
6. make updatescript executable
7. add updatescript to /etc/crontab: 0 3 * * * root bash /usr/local/bin/update-minecraft.sh