I'm trying to start a minecraft server by sending some commands to an EC2 instance using the AWS-SDK for javascript.

ssm.sendCommand({
  DocumentName: "AWS-RunShellScript",
  InstanceIds: ["ec2-instance-id"],
  TimeoutSeconds: 3600,
  Parameters: {
    commands: ['cd /home/ec2-user/minecraft/server', 'screen -S mc_server', 'java -Xmx3G -Xms3G -jar server-1-18.jar nogui']
  }}, function(err, data) {
    if (err) {
      console.log("\nError:", err);
    } else {
      console.log("\nSuccess: ", data);
    }
  }
);

The command works correctly and I'm able to connect to the server after some waiting. The detail that bothers me is that the last command (java -Xmx3G -Xms3G -jar server-1-18.jar nogui) never finishes executing because it continously logs the different server events until the server is stopped manually. However, when the server finishes loading it prints to the stdout something like:

Done! Finished in xxx seconds.

I would like to track the command stdout and signal the SSM executor to mark the command as finished, after that line is shown. I need to do this, because to stop the server properly, I need to re-attach the screen and then send the command /stop, but because the previous command is still running, it returns an error.

My overall goal is to start the server with a script, and then be able to stop it properly. I know I could just stop the instance to stop the server, but this could lead to corrupted chunks in my world. Maybe there is a better way to do this. Any help is appreciated. Thanks!