bash script to start / stop / restart solr

#!/bin/bash

log_file=solr-server.log
pid_file=solr-server.pid
process_name="solr"
function stop {
   if [ ! -f "$pid_file"  ]; then
      printf "$process_name is not running\n"
      exit 1
   else
      printf "Stopping $process_name...\n"
      pid=`cat $pid_file`
      kill "$pid"
      rm $pid_file
      sleep 1
      echo "Done"
   fi
}


function start {
   if [ ! -f "$pid_file" ]; then
      printf  "Starting $process_name...\n"
      java -jar  start.jar > $log_file 2>&1 &
      echo $! > $pid_file
      sleep 1
      pid=`cat $pid_file`
      printf "pid=$pid\nDone\n"
   else
      pid=`cat $pid_file`
      printf "$process_name is already running\npid=$pid"
   fi
}

function restart {
   printf  "Restarting $process_name...\n"
   stop
   sleep 1
   start
}




case "$1" in
   start)
      start
   ;;
   stop)
      stop
   ;;
   restart)
      restart
   ;;
   status)
      status
   ;;
   *)
    restart
    #  echo "Usage: $0 {start|stop|restart|status}"
esac