How to get a list of all file extensions that are associated to a particular application?

Question

How can I pick an application and then generate a list of all the files extensions that are currently associated with it?

Windows Explorer's Folder Options utility lets me go the other way - that is see what application a particular file extension is associated to, but I would like to view a per-application list of associated extensions. I was really hoping I could just add an "Application" column to the Folder Options utility and then just sort by it.

Is there an native utility to do this? Third-party application? Can I find this information in the registry?

Answer 1

Try to find the internal name (or whatever you call this) of the Application Association. If you know one associated extension for sure, run assoc and filter all entries containing the known extension. After the = you see the internal name of the application the extension is linked to. Select a unique part of that name and do a second search. Here I did it for the MediaPlayer (name "WMP11"):

C:\Users\me>assoc | find "mp3"
.mp3=WMP11.AssocFile.MP3

C:\Users\me>assoc | find "WMP11"
.asf=WMP11.AssocFile.ASF
.asx=WMP11.AssocFile.ASX
.au=WMP11.AssocFile.AU
.avi=WMP11.AssocFile.AVI
.cda=WMP11.AssocFile.CDA
.m1v=WMP11.AssocFile.MPEG
.M2V=WMP11.AssocFile.MPEG
<snip>