I'm a beginner in php developing and I want to bring advanced file search functionality in my php web application.

How could I realize that?

I want to build a search form within my php web site which gives the users the possibility to search for files which are saved in a special directory on my webserver. This directory contains only files which are uploaded by registrated users.

The script I need should check files' names but also the files' contents.

Any ideas? I think there must be existing scripts - freeware or commercial stuff.

Could anybody help me?