Shell script to daemonise a ruby process

app_ctl

#!/bin/sh
#
# Script:      app_ctl
# Description: Starts and stops a Ruby script
#

die()
{
        echo "$*"
        exit 1
}

APP_PID=./app.pid

case $1 in
        start)
                        if [ -f "$APP_PID"  -a ! -f /proc/`cat $APP_PID` ]
                        then
                                echo "App is already running"
                                exit 1;
                        fi
                        nohup ruby ./app.rb &
                        echo $! > $APP_PID
                        ;;
        stop)   if [ ! -f "$APP_PID" ]
                        then
                                echo "App is not running (no PID file)"
                        else
                                kill `cat $APP_PID`
                                rm -f $APP_PID
                        fi
                        ;;
        status) ;;
        *)              echo "Usage: `basename $0` {-start|-stop|-status}"
                        exit 1
                        ;;
esac

exit 0