Saving NetNews with Tcl(lib)

Given my various interests I am following several groups like <news:comp.lang.tcl> and <news:comp.risks> on NetNews, a global bulletin board system which was started shortly after the internet itself.

Due to the ephemeral nature of the various boards' contents, with most servers keeping messages for only a week or two, any access to older messages means that I either have go to some website which backs them up, like Google Groups, or save them on my own.

Here I describe how to do the latter, using Tcl and Tcllib.