[kstenerud]

No, please, no interactivity! Make a decision here and now.

A better approach to the "use stable" part of nvm:

    $ /.nvm use stable

    Node stable (5.0.0) not found. Installing...

    Now using node v5.0.0.

    Setting v5.0.0 as the default since it's the only version installed. To change the default, run 'nvm default <version>'

[TeMPOraL]

Related, know your users. NVM is a tool for programmers, and programmers like to:

1) Batch things. Hence no interactivity is a good thing, like you pointed out.

2) Know what's going on in the system. If `nvm use` both selects a node version and installs it if missing, then I want to also have `nvm install` and `nvm select* commands - the former so I can batch stuff, and the latter to feel confident that issuing it won't do significant changes to my system, won't download stuff, and otherwise won't break anything.