mv command
 

I have a directory called command_expansion_test.

The directory contains the files: test.ogg, test2.ogg, test3.ogg.

Using the mv command, how can I change the filenames to test.mp3, test2.mp3, test3.mp3 ?

If you have the rename command, it straightforward as
otherwise you can use sed to substitute the extension as in

Thanks colucix:

rename would be the easy way to do it. I never seem to want to do things the easy way however.

This is mostly an academic exercise for me. I was at a LUG last night where the presenter used a string very similar to the one you provided to perform a *.ogg to *.mp3 name change to files in a directory.

I've been banging my head against a wall trying to come up with a single string that can do it, but now I realize that it probably was a script.

Well
I would say you're on the right track, I usually refer to this document for such tasks.

Not really a script: you can launch a for loop directly in the command line. As you can see from the document suggested by Junior Hacker, usually there are a lot of ways to perform the same task. It is a matter of efficiency or elegance or whatever you are focused on.

The reason I have a love/hate relationship with Linux: I start out trying to learn how to do some seemingly trivial task, and discover a relatively broad new facet to Linux (and computers). I believe I just stumbled upon "structured Language Constructs," as defined here http://www.freeos.com/guides/lsst/index.html

Thanks for your help!