Shell script that returns http code from a list of sites

gistfile1.txt

#!/bin/bash

INPUT=sites.txt
OLDIFS=$IFS
IFS=,
[ ! -f $INPUT ] && { echo "$INPUT file not found"; exit 99; }
while read SITE
do


curl -o /dev/null --silent --head --write-out '%{url_effective},%{http_code}\n' $SITE

sleep 1


done < $INPUT
IFS=$OLDIFS

echo -e "Done :-)\n\n"