The modpack you installed (if its from CurseForge as I understand) would have a start.sh file (for linux) or start.ps1/start.bat file (for Windows) that you use to normally start the server. This script does everything for you but it's difficult to make it work with msh
You cannot simply make msh run the start file so you need to tell it exactly what command to run. In my case I could do this by piping the output of the start file to another file, luckily it lists the exact command that is being run right at the top so all you have to do is copy that command and paste it in the StartServer command variable.
The Folder variable will probably be the folder where you start.sh file and the FileName is also probably in that same folder (in my case it was named fabric-server-launcher.jar ). You can also find this just by looking at the output of the start file as it calls the correct launcher file
I haven't changed anything else other than TimeBeforeStoppingEmptyServer to 120 and it works as intended. Thanks to the dev for making this amazing script
from yoichi#6020 (discord):