I need a plugin that allows me to nagios looking for a well-defined text in the content of my web page. if the text is found I would ok sion error who can help me please
The standard plugin
check_http -H [hostname] -I [ip address] -u [url] -R [text to match]
The check will fail for the usual reasons, but also if the text (or regular expression) is not found in the returned page.
If you want to fail if the text is found, add the option
Flup's answer seems great for a simple page.
If you want to do something similar but need to navigate through a set of login pages, we make use of http://webinject.org/ which allows a test to fill in forms etc.