How to exit a cgi file after a download

[random832 at fastmail.us]

On Wed, Sep 4, 2013, at 12:49, Ferrous Cranus wrote:
> Without closing it, the client can download 
> again and forever if they choose to because 
> the cgi window is open and the link is still 
> active. 

Why is this a problem? They usually won't want to, and if they do want
to (for example if they accidentally canceled the download) I don't see
why not to let them.

The solution should be to give them a unique download link that will
only work once (or only for a certain period of time), not to close the
window.