how to make gnus print various group lists to stdout

[Harry Putnam <reader@newsguy.com>]

I know gnus has a multitude of ways to list, and equally many to sort
groups so combining them constitute nearly any sort of informative
display one can think of.

I'd like to be able to push some of that to STDOUT to be captured in
files or whatever.  Examples so you understand what I mean:

List of of all level (N) groups.  A list of all subscribed nntp
groups.  Lists of groups belonging to each backend. List of agentized
groups.

Etc.  Gnus knows about all those I believe...And is willing and able
to display them.

But only the elisp adepts among us are able to get that infomation in
a form amenable to scripting with other tools (Perl I have in mind but
there are. of course, many others.)

For some of what I'm fiddling with it would be very handy to have some
of that information available on STDOUT.

Can anyone offer some ways to get at that kind of information other
than viewing it inside emacs, and creating a file from the buffer?