Script will restart a Minecraft server after a Crash and in the process remove pid created by the script, remove ./world/session.lock and kill old process if still running.

start-server-with-pid.sh

#!/bin/bash

MINECRAFT_VERSION=1.18.1

set -euo pipefail
cd ${0%/*}
PIDFILE=./minecraft.pid
SESSION_LOCK=./world/session.lock

GREEN='\033[0;32m'
RED='\033[0;31m'
NC='\033[0m' # No Color

function restart() {
  echo -e "${RED}------------------------------------------------------${NC}" | tee -a start-server-with-pid.log
  echo -e "${RED}Getting ready to restart Minecraft version : $MINECRAFT_VERSION${NC}" | tee -a start-server-with-pid.log
  echo -e "${RED}Minecraft crached at $(date +'%Y-%m-%d %H:%M:%S')${NC}" | tee -a start-server-with-pid.log
  if [[ -f $PIDFILE ]]; then
    echo -e "${RED}    - Remove the file $PIDFILE as part of restart${NC}" | tee -a start-server-with-pid.log
    rm $PIDFILE
  fi
  if [[ -f $SESSION_LOCK ]]; then
    echo -e "${RED}    - Remove the file $SESSION_LOCK as part of restart${NC}" | tee -a start-server-with-pid.log
    rm $SESSION_LOCK
  fi
  PID_OF_PORT_IN_USE=$(lsof -i:25565 | grep LISTEN | awk '{print $2}')
  if [[ "X" != "X$PID_OF_PORT_IN_USE" ]]; then
    echo -e "${RED}    - Kill existing Minecraft server running on port 25565 as part of restart${NC}" | tee -a start-server-with-pid.log
    kill -9 $PID_OF_PORT_IN_USE
  fi
  echo -e "${RED}------------------------------------------------------${NC}" | tee -a start-server-with-pid.log
  exec "./start-server-with-pid.sh"
}

#  PID file
if [[ -f $PIDFILE ]]; then
  pid=$(cat $PIDFILE)
  ps -p $pid > /dev/null 2>&1
  if [ $? -eq 0 ]; then
    echo "Minecraft is already running" | tee -a start-server-with-pid.log; exit 1
  else
    # process not found, overwrite
    echo $$ > $PIDFILE;
  fi
else
	# wasn't running, write pid
  echo $$ > $PIDFILE;
fi

# after PID file has been set
trap restart EXIT

export JAVA_HOME="/opt/java/jdk-17.0.1+12"

echo "" | tee -a start-server-with-pid.log
echo -e "${GREEN}Getting ready to start Minecraft version : $MINECRAFT_VERSION${NC}" | tee -a start-server-with-pid.log
echo -e "${GREEN}Minecraft starting at $(date +'%Y-%m-%d %H:%M:%S')${NC}" | tee -a start-server-with-pid.log
echo "JAVA_HOME : $JAVA_HOME" | tee -a start-server-with-pid.log
echo "" | tee -a start-server-with-pid.log

$JAVA_HOME/bin/java -Xmx2048M -Xms2048M -jar server_$MINECRAFT_VERSION.jar nogui