[off-topic] remove app association from file extension

[Ryan Schmidt]

On Apr 19, 2019, at 16:25, Helmut K. C. Tessarek wrote:

> I want macOS to let me choose the app every time I double click on an
> .md file.

I don't think macOS has this capability built-in.

I just created a new file with an unusual extension. I opened it in the Finder and it said there's no application that can open it. When I clicked Choose Application in that dialog and chose an application, it opened the file into that application. When I went back to the Finder and opened the file again, it didn't ask again; it opened it with the app I previously selected.

There is an app called Choosy that lets you configure what happens when you click a URL outside of a web browser. It can be configured to ask every time which browser should open the URL. This only works for URLs, but it illustrates that it would be possible to write a program that does the same thing for file MIME types or extensions. You would tell the OS that you want .md files to open into this new hypothetical application, and the app would then ask you what program you really want to open it with. It would probably not be too difficult to write such a program. There may even be one out there already.