I have limited understanding about cron commands, I have tried using one particular url, but I would like the script to get a comma delimited list of URL’s and check their http response every 5 minutes for 30 minutes. Then output the result. My guess is:
5 * * * * /usr/bin/wget "www.example.com" --timeout 30 -O - 2>/dev/null | \
grep "Normal operation string" || echo "The site is down" | \
/usr/bin/mail -v -s "Site is down" your@e-mail.address
But it works for one particular predefined website only