[imp] Error with test.php

[Rick Emery]

OK, IMP works perfectly and I'm having no problems with it. However, I 
see that people get a lot of good information about their systems by 
going to test.php with their web browser, and I would also like to do that.

Unfortunately, I get the following error:

Warning: Failed opening '/var/www/html/horde/test.php' for inclusion 
(include_path='/usr/share/php:/usr/share/pear:.') in Unknown on line 0

 From the error message, I assume I need to change my "include_path", 
since I have a directory called /usr/share/pear, but no /usr/share/php 
(there is a php directory under /usr/lib; could that be the one I 
want?). Anyway, can anybody help me configure this correctly? If it's 
the problem, I don't know how to change the value of "include_path".

Thanks in advance,
Rick