How do I find which rpm package supplies a file I’m looking for?

As an example, I am looking for a mod_files.sh file which presumably would come with the php-devel package. I guessed that yum would install the mod_files.sh file with the php-devel x86_64 5.1.6-23.2.el5_3 package , but the file appears to not to be installed on my filesystem. How do I find out which package installs the specific file? I’m looking for where I have not necessarily already locally downloaded the package which may include the file that I’m looking for?

I’m using CentOS 5.

How do I find which rpm package supplies a file I’m looking for?