in reply to questions concerning using perl to monitor webpages
The HTTP protocol helps, as there is a "If-Modified-Since"
header. So, you could use LWP, create an user agent, and
an HTTP Request object, set the "If-Modified-Since" header,
do the request, and look at the return status of the response.
If the status is 304, the content hasn't changed. If the status is 200, the content has changed. For any other status,
see RFC 2068.
Abigail
In Section
Seekers of Perl Wisdom