bash wget - check if file exists at url before downloading

validate.sh

#!/bin/bash

# simple function to check http response code before downloading a remote file
# example usage:
# if `validate_url $url >/dev/null`; then dosomething; else echo "does not exist"; fi


function validate_url(){
  if [[ `wget -S --spider $1  2>&1 | grep 'HTTP/1.1 200 OK'` ]]; then echo "true"; fi
}

url="URL_TO_CHECK"
if `validate_url $url >/dev/null`; then echo "FILE IS READY!!!"; else echo "does not exist"; fi

Great way to have it checked every 60 seconds:
watch -n60 bash validate.sh