Script to add new monitors in Nagios

nagios-newmonitor.sh

#!/bin/bash
# newpingmonitor.sh
# Sets up monitoring for new basic ping monitors in nagios
# Ths script may be called remotely

E_BADARGS=65

if [ ! -n "$1" ]
then
  echo "Usage: `basename $0` <servername> <ip address>"
  exit $E_BADARGS
fi

echo "define host{
        use generic-host
        host_name ${1}
        alias ${1}
        address ${2}
}" >> /etc/nagios3/conf.d/$1.cfg

echo "> Successfully created Nagios monitor."

echo "> Restarting Nagios daemon..."
service nagios3 restart

what if same host exists already?