Hey there! Let's tackle this auto-shutdown logic for your Minecraft servers step by step. Since you already know bash basics, rcon, and Wake-on-LAN, we'll focus on building the core monitoring, timing, and trigger system you need.

1. Core Logic Overview #

The key idea is straightforward:

• Monitor all your Minecraft server ports for active TCP connections
• Track the last time any connection was detected
• When no connections are found for 30 minutes straight:
  1. Gracefully shut down all Minecraft servers via rcon
  2. Power off the host machine

2. Script Setup & Configuration #

First, create a bash script (e.g., mc-auto-shutdown.sh) with configurable variables for your servers. This makes it easy to add/remove servers later.

#!/bin/bash
set -euo pipefail  # Enable strict error handling to catch bugs early

# -------------------------- CONFIGURATION AREA --------------------------
# Define your Minecraft servers: format is "PORT:RCON_SHUTDOWN_COMMAND"
# Replace with your actual rcon command (adjust based on your rcon tool, e.g., mcrcon)
MC_SERVERS=(
  "25565:mcrcon -H localhost -P 25565 -p your-rcon-password-1 stop"
  "25566:mcrcon -H localhost -P 25566 -p your-rcon-password-2 stop"
)
INACTIVE_THRESHOLD=1800  # 30 minutes in seconds (1800)
CHECK_INTERVAL=60        # Check connections every 60 seconds (adjust as needed)
# -----------------------------------------------------------------------

# Initialize timestamp of last detected active connection
LAST_ACTIVE_TIMESTAMP=$(date +%s)

3. Connection Detection Function #

This function checks all your configured server ports for established TCP connections (using the lsof command you already know). It returns 0 (success) if any active connection is found, 1 otherwise.

check_active_connections() {
  local has_active=1  # Default to no active connections
  for server in "${MC_SERVERS[@]}"; do
    # Extract the port from the server config
    local port=$(echo "$server" | cut -d: -f1)
    # Check if the port has any established TCP connections
    if lsof -iTCP:"$port" -sTCP:ESTABLISHED -t > /dev/null; then
      has_active=0  # Found active connection
      break  # No need to check other servers
    fi
  done
  return $has_active
}

4. Main Monitoring Loop #

This is the heart of the script: it runs continuously, checks for connections, updates the last active timestamp, and triggers shutdown when the threshold is hit.

echo "$(date): Starting Minecraft auto-shutdown monitor..."

while true; do
  if check_active_connections; then
    # Active connection detected: reset the last active timestamp
    LAST_ACTIVE_TIMESTAMP=$(date +%s)
    echo "$(date): Active connection detected - resetting inactivity timer"
  else
    # No active connections: calculate time since last activity
    CURRENT_TIMESTAMP=$(date +%s)
    TIME_SINCE_LAST=$((CURRENT_TIMESTAMP - LAST_ACTIVE_TIMESTAMP))
    echo "$(date): No active connections - elapsed time: $TIME_SINCE_LAST seconds"

    # Check if we've exceeded the inactivity threshold
    if [ "$TIME_SINCE_LAST" -ge "$INACTIVE_THRESHOLD" ]; then
      echo "$(date): Inactivity threshold reached! Starting shutdown process..."
      
      # Step 1: Gracefully shut down all Minecraft servers via rcon
      for server in "${MC_SERVERS[@]}"; do
        local port=$(echo "$server" | cut -d: -f1)
        local rcon_cmd=$(echo "$server" | cut -d: -f2-)
        echo "$(date): Shutting down server on port $port..."
        $rcon_cmd
        # Wait 30 seconds for the server to save and exit (adjust as needed)
        sleep 30
      done

      # Step 2: Power off the host machine
      echo "$(date): All servers shut down. Powering off host..."
      shutdown -h now
      exit 0  # Exit script after shutdown
    fi
  fi

  # Wait before next check
  sleep "$CHECK_INTERVAL"
done

5. Make the Script Run in Background & On Boot #

To ensure the script runs continuously (even after reboot), set up a systemd service:

1. Save the script and make it executable:

   chmod +x /path/to/mc-auto-shutdown.sh
   

2. Create a systemd service file (e.g., /etc/systemd/system/mc-auto-shutdown.service):

   [Unit]
   Description=Minecraft Auto Shutdown Monitor
   After=network.target
   
   [Service]
   User=your-minecraft-user  # Replace with the user running your MC servers
   ExecStart=/path/to/mc-auto-shutdown.sh
   Restart=always  # Restart the script if it crashes
   RestartSec=5
   
   [Install]
   WantedBy=multi-user.target
   

3. Enable and start the service:

   sudo systemctl daemon-reload
   sudo systemctl enable mc-auto-shutdown.service
   sudo systemctl start mc-auto-shutdown.service
   

6. Optional Enhancements #

• Add player warnings: Before shutting down, send a message to all players via rcon (e.g., say Server will shut down in 5 minutes due to inactivity!) and wait 5 minutes.
• Test with shorter thresholds: Set INACTIVE_THRESHOLD=60 (1 minute) to test the script without waiting 30 minutes.
• Log to a file: Redirect script output to a log file for debugging (add >> /var/log/mc-auto-shutdown.log 2>&1 to the ExecStart line in the systemd service).

内容的提问来源于stack exchange，提问作者BloxBoss6