A basic bash startup script with aikar's flag for starting Minecraft servers

start.sh

#!/bin/bash

# define the java or path of a java version you need (default: java)
JAVA="java"

# name of the server .jar file
JAR_FILE="server.jar"

# define max ram (1024M/1G 2048M/2G...)
MAX_RAM=8G

# agree EULA of minecraft without editing eula.txt. Please note, this is still legally binding that you have read and agree to the Minecraft EULA. (true/false)
ACCEPT_EULA=true

# puts all your world folders into a specific folder. If you leave blank, nothing will change (worlds, files/worlds...)
WORLD_DIRECTORY="worlds"

# sets timezone of JVM. useful for those who have a server in a foreigner country (https://en.wikipedia.org/wiki/List_of_tz_database_time_zones)
TIMEZONE="Europe/Istanbul"

# auto restart on shutdown
RESTART=false

# print something
echo Starting the server...

# do the actual work
${JAVA} -Xms${MAX_RAM} -Xmx${MAX_RAM} -XX:+UseG1GC -Duser.language=en -XX:+ParallelRefProcEnabled -XX:MaxGCPauseMillis=200 -XX:+UnlockExperimentalVMOptions -XX:+DisableExplicitGC -XX:+AlwaysPreTouch -XX:G1NewSizePercent=30 -XX:G1MaxNewSizePercent=40 -XX:G1HeapRegionSize=8M -XX:G1ReservePercent=20 -XX:G1HeapWastePercent=5 -XX:G1MixedGCCountTarget=4 -XX:InitiatingHeapOccupancyPercent=15 -XX:G1MixedGCLiveThresholdPercent=90 -XX:G1RSetUpdatingPauseTimePercent=5 -XX:SurvivorRatio=32 -XX:+PerfDisableSharedMem -XX:MaxTenuringThreshold=1 -Dusing.aikars.flags=https://mcflags.emc.gs -Daikars.new.flags=true -Duser.region=EN -Dfile.encoding=UTF-8 -Dcom.mojang.eula.agree=${ACCEPT_EULA} -Duser.timezone="${TIMEZONE}" -jar $JAR_FILE nogui --world-dir "./${WORLD_DIRECTORY}" 

# check if auto restart is true
if  [[ "$RESTART" == true ]]; then
    eval "bash $(basename "$0")"
fi

# ask to restart
read -p "Restart the server? [Y/N]: " chosen
if [[ "$chosen" == "Y" ]] || [[ "$chosen" == "y" ]]; then
    # restart if "y" or "Y" is entered
    eval "bash $(basename "$0")"
fi

echo Server closed.