How can I set up Nagios to monitor a webpage?

Question

How can I set up Nagios 3 to monitor a webpage? I would like to make sure it stays online. Also, if possible, I would like to have it check the page for a string to make sure the page is valid.

Answer 1

You can use the plugin check_http. It has an option called -s, --string=STRING String to expect in the content.

Answer 2

The Nagios check_http plugin does exactly what you're asking, and more.
Refer to the Nagios Manual for information on how to set up Nagios and configure plugins if you are unsure how to do so.