#!/bin/bash

which whois >/dev/null || { echo "whois - not installed"; exit 1; }
[ -z "${1}" ] && { echo "domain - not spicified"; exit 1; }
now=$(date '+%s')
expiration_date=$(date -d "$(whois "${1}" | grep 'Registry Expiry Date'|awk -F ': ' '{print $2}')" '+%s')
echo $(( ( expiration_date - now )/(60*60*24) ))