Node startup

#!/bin/sh

USER="pi"
APP_DIR="/home/pi/Desktop/Lights-Berry"
NODE_APP="app.js"
CONFIG_DIR="$APP_DIR"
PID_DIR="$APP_DIR/pid"
PID_FILE="$PID_DIR/app.pid"
LOG_DIR="$APP_DIR/log"
LOG_FILE="$LOG_DIR/app.log"
NODE_EXEC=$(which node)
APP_NAME="Lights"
USAGE="Usage: $0 { start | stop | restart }"

###############

# REDHAT chkconfig header

# chkconfig: - 58 74
# description: Lights is the script for starting Lights on boot.

### BEGIN INIT INFO
# Provides: node
# Required-Start:    $all
# Required-Stop:     $all
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: start and stop node.
# Description: Node process for an app.
### END INIT INFO

###############

pid_file_exists() {
  [ -f "$PID_FILE" ]
}

get_pid() {
  echo "$(cat "$PID_FILE")"
}

remove_pid_file() {
  echo "Removing pid file"
  rm -f "$PID_FILE"
}

is_running() {
  PID=$(get_pid)
  ! [ -z "$(ps aux | awk '{print $2}' | grep "^$PID$")" ]
}

start_it() {
  echo "Starting $APP_NAME..."
  echo "cd $APP_DIR && (NODE_CONFIG_DIR=$CONFIG_DIR $NODE_EXEC $APP_DIR/$NODE_APP 1>$LOG_FILE 2>&1 & echo \$! > $PID_FILE)" | sudo -i -u $USER
  echo "$APP_NAME started with pid $(get_pid)"
}

stop_process() {
  PID=$(get_pid)
  echo "Killing process $PID"
  kill -9 $PID
}

start_app() {
  if pid_file_exists
  then
      if is_running
      then
        PID=$(get_pid)
        echo "$APP_NAME already running with pid $PID"
        exit 1
      else
        echo "$APP_NAME stopped, but pid file exists"
        remove_pid_file
        start_it
      fi
    else
      start_it
    fi
}

stop_app() {
  if pid_file_exists
  then
    if is_running
    then
      echo "Stopping $APP_NAME..."
      stop_process
      remove_pid_file
      echo "$APP_NAME stopped"
    else
      echo "$APP_NAME already stopped, but pid file exists"
      remove_pid_file
    fi
  else
    echo "$APP_NAME already stopped, pid file does not exist"
    exit 1
  fi
}

case "$1" in
    start)
      start_app
    ;;
    stop)
      stop_app
    ;;
    restart)
      stop_app
      start_app
    ;;
    *)
      echo $USAGE
      exit 1
    ;;
esac