* Look for a value in an ENV var
* Look for existing dirs that make sense
* Prompt to create things if the above doesn't workout

When you prompt to create the needed dir, you might want to display a reasonable default and wait for the user to hit return. This is an often seen pattern that is great because it:

* demonstrates to the user what is happening
* Allows things to be stop/changed by the user
* And "does the right thing" if the user just accepts the defaults

Cheers

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Nothing is too wonderful to be true
-- Michael Faraday