Bash loop to test URL propagation, including notifications when propagated

gistfile1.sh

propagate(){

  # Reminder for arguments
  if [ "$1" == "-h" ]; then
  echo "Arguments:
  1: URL
  2: New IP
  Example: website.com 879.30.33.21"
  return
  fi

  curr_ip=`nslookup $1 | grep Address | sed -n '2p' | cut -d: -f2|sed 's/^[ \t]*//'`

  while [ "${2}" != "$curr_ip" ]; do
    echo "$curr_ip $(date "+%T")"
    sleep 300
    curr_ip=`nslookup $1 | grep Address | sed -n '2p' | cut -d: -f2|sed 's/^[ \t]*//'`
  done

  echo "${1} has propagated to ${2}"

  # Echo to Notification Center (requires terminal notifier Ruby gem https://github.com/alloy/terminal-notifier)
  terminal-notifier -message "${1} has propagated to ${2}" -title "Propagation Complete" -sound "Glass"

  # Other notifications
  # (I use curl to text myself via the Twilio API in case I'm AFK

}