how to create a system service in linux

create a script file with the following lines - 

#!/bin/sh 
SERVICE_NAME=Your_Service_Name 
#PATH_TO_JAR=/usr/Name_of_User/MyJavaApplication.jar 
PID_PATH_NAME=/tmp/Service_Name-pid 
case $1 in 
start)
       echo "Starting $SERVICE_NAME ..."
  if [ ! -f $PID_PATH_NAME ]; then 
       <command u want to run (eg sh sample_script.sh or java sample_java)>  
       #eg nohup java -jar $PATH_TO_JAR /tmp 2>> /dev/null >> /dev/null &
                   echo $! > $PID_PATH_NAME  
       echo "$SERVICE_NAME started ..."         
  else 
       echo "$SERVICE_NAME is already running ..."
  fi
;;
stop)
  if [ -f $PID_PATH_NAME ]; then
         PID=$(cat $PID_PATH_NAME);
         echo "$SERVICE_NAME stoping ..." 
         kill $PID;         
         echo "$SERVICE_NAME stopped ..." 
         rm $PID_PATH_NAME       
  else          
         echo "$SERVICE_NAME is not running ..."   
  fi    
;;    
restart)  
  if [ -f $PID_PATH_NAME ]; then 
      PID=$(cat $PID_PATH_NAME);    
      echo "$SERVICE_NAME stopping ..."; 
      kill $PID;           
      echo "$SERVICE_NAME stopped ...";  
      rm $PID_PATH_NAME     
      echo "$SERVICE_NAME starting ..."  
      <command u want to run (eg sh sample_script.sh or java sample_java)>  
      #eg nohup java -jar $PATH_TO_JAR /tmp 2>> /dev/null >> /dev/null &
      echo $! > $PID_PATH_NAME  
      echo "$SERVICE_NAME started ..."    
  else           
      echo "$SERVICE_NAME is not running ..."    
     fi     ;;
 esac
 
 
 test the script 
 
 sh script_name.sh start
 sh script_name.sh stop
 sh script_name.sh restart
 
 do cd /etc/systemd/system
 
create a file with the following format

touch <service_name>.service
eg : touch hari.service  #a service with name hari will be created

do vi hari.service and add the following lines

[Unit]
 Description = Java Service
 After network.target = Service_Name.service
[Service]
 User=root(or any other user name u want to run the process with)
 Type = forking
 Restart=always
 RestartSec=1
 SuccessExitStatus=143 
 ExecStart = /usr/local/bin/Service_Name.sh start 
 ExecStop = /usr/local/bin/Service_Name.sh stop
 ExecReload = /usr/local/bin/Service_Name.sh reload
[Install]
 WantedBy=multi-user.target
 
 
 save the file
 
 sudo systemctl daemon-reload
sudo systemctl enable Service_Name
sudo systemctl start  Service_Name
sudo systemctl stop   Service_Name


reference  - 
https://medium.com/@ameyadhamnaskar/running-java-application-as-a-service-on-centos-599609d0c641