How to Run a Minecraft Server Jar

The command

java -Xms4G -Xmx4G -jar server.jar nogui

• java — the Java runtime. It must be the version your Minecraft version needs (table). If several are installed, use the full path, e.g. "C:\Program Files\Eclipse Adoptium\jdk-21…\bin\java.exe" or /usr/lib/jvm/…/bin/java.
• -Xms4G -Xmx4G — initial and maximum heap memory. Setting both to the same value is what PaperMC recommends for dedicated servers. See how much RAM.
• -jar server.jar — the server file; replace it with your file name (for example paper-1.21.11-132.jar).
• nogui — don't open the vanilla console window; run in the terminal only.

Run it from inside the server folder: the server uses the current directory for the world, server.properties and logs.

Windows: start.bat

Create a text file named start.bat in the server folder (make sure Windows doesn't save it as start.bat.txt) with:

@echo off
cd /d "%~dp0"
java -Xms4G -Xmx4G -jar server.jar nogui
pause

cd /d "%~dp0" switches to the script's folder, so a double-click works from anywhere; pause keeps the window open so you can read errors.

Linux / macOS: start.sh

#!/bin/sh
cd "$(dirname "$0")"
java -Xms4G -Xmx4G -jar server.jar nogui

Make it executable once with chmod +x start.sh, then run ./start.sh. On a remote server, start it inside screen or tmux so it keeps running after you disconnect:

tmux new -s mc ./start.sh      # detach: Ctrl+B then D, re-attach: tmux attach -t mc

Automatic restart after a crash or /stop

Linux/macOS:

#!/bin/sh
cd "$(dirname "$0")"
while true; do
  java -Xms4G -Xmx4G -jar server.jar nogui
  echo "Server stopped. Restarting in 10 seconds (Ctrl+C to cancel)…"
  sleep 10
done

Windows:

@echo off
cd /d "%~dp0"
:start
java -Xms4G -Xmx4G -jar server.jar nogui
echo Server stopped. Restarting in 10 seconds (close the window to cancel)...
timeout /t 10
goto start

Types that start differently

• Forge 1.17+ and NeoForge: there is no single jar to run. The installer creates run.sh/run.bat, and memory goes into user_jvm_args.txt — see the Forge and NeoForge guides.
• Fabric: run the Fabric server launcher jar like any server jar; it downloads the vanilla server on first start (guide).
• Spigot/CraftBukkit: build the jar with BuildTools first (guide), then run it as above.
• Proxies (Velocity, BungeeCord): same command without nogui and with much less memory (512 MB–1 GB); no EULA.

Paper, Purpur and Folia benefit from Aikar's G1 flags; every version page on MCJarHub includes a ready start script with them, and the start script generator builds one for your RAM, OS and server type.