[Q] website watcher for Linux?

[Ken N9VV]

Hi, I have a favorite Windows application called WebsiteWatcher. It 
checks websites for updates. It works like a dream under Windoze and 
often alerts me to software updates or important changes on a vendor's 
website. I can't find anything similar under Linux. I thought I had seen 
a Perl module in the distant past, but can not find it now. Any ideas?
thanks,
ken