Wondering how to setup server with startup script im using moonlight panel atm

hey i wanted to know how would i use a startup script on my server im using the curseforge egg right now with rlcraft and wanna optimize it some more. i have the script from flags sh. its running fine but I want more optimizations to be sure.

java $([[ -f user_jvm_args.txt ]] && printf %s "@user_jvm_args.txt") -Xms128M -Xmx{{SERVER_MEMORY}}M -Dterminal.jline=false -Dterminal.ansi=true $([[ ! -f unix_args.txt ]] && printf %s "-jar cat .serverjar" || printf %s "@unix_args.txt") is the script by default