Listing the unique file ids of files

I'm looking to link a set of files to a set of meta information, and I want to uniquely identify the files - and have some perl do processing to combine the files with meta data - so I can cross reference them with a unique id.

So I found that if you type "ls -i" it gives the unique file ids for the files - on OS X in the terminal.

Very useful, I'll remember that.