In the group buffer typing G G will search the group on the
current line by calling gnus-group-read-ephemeral-search-group.
This prompts for a query string, creates an ephemeral nnselect
group containing the articles that match this query, and takes you to
a summary buffer showing these articles. Articles may then be read,
moved and deleted using the usual commands.
The nnselect group made in this way is ephemeral: it
will disappear upon exit from the group. However changes made in the
group are permanently reflected in the real groups from which the
articles are drawn. If you want to create a persistent group
that sticks around after exit from the summary buffer, you can call
gnus-group-make-search-group (bound to G g).
Unlike persistent groups, ephemeral groups by default do not run
articles through the expiry process on exiting. If you want expiry to
happen in ephemeral search groups you can customize the variable
nnselect-allow-ephemeral-expiry. In all cases the expiry
process uses the underlying group’s expiry parameters.
So you just performed a search whose results are so fabulous you
wished you had done a persistent search rather than an ephemeral one?
No problem; you can create such a group by calling
gnus-summary-make-group-from-search (bound to C-c C-p)
from the ephemeral summary buffer.
It is occasionally convenient to view articles found through searching
in their original group. You can warp (i.e., jump) to the
original group for the article on the current line with A W, aka
gnus-warp-to-article.
You say you want to search more than just the group on the current line? No problem: just process-mark the groups you want to search. You want even more? Initiating a search with the cursor on a topic heading will search all the groups under that topic.
Still not enough? OK, in the server buffer
gnus-group-read-ephemeral-search-group (here bound to G)
will search all groups from the server on the current line. Too much?
Want to ignore certain groups when searching, like spam groups? Just
customize gnus-search-ignored-newsgroups: groups matching this
regexp will not be searched.