Minecraft wiki entry for Server_startup_script, associated text: Now you can Upload your FTB Modpacks into an subfolder of /opt/minecraft/. For example, you would place the modpack "FTB Beyond" in "/opt/minecraft/FTBBeyond" (without spaces in the name). If you want to run vanilla instances, just create a folder within /opt/minecraft and upload the minecraft_server.jar and create the eula.txt file (using: echo "eula=true" > /opt/minecraft/vanilla/eula.txt).