arrow keys don't work

[tac-tics]

Robert Kern wrote:
> tac-tics wrote:
> > I've noticed that in Python 2.5, the interactive prompt does not
> > support intelligent use of arrow keys like 2.4 did (up/down for
> > previous/next statement, left/right for moving the cursor). What
> > exactly is the reason for this and is there an easier fix than
> > downgradinig to 2.4? Thanks.
>
> Your installation of 2.4 probably had the readline module installed while your
> installation of 2.5 doesn't. What platform are you on?

Actually, I should have posted this a while ago. I've noticed it on
Ubuntu Linux, Mac OSX, and earlier today on Sun Solaris.

What do I need to do to install / configure readline?