Searching multiple buffers emacs

FSF has two magic functions for searching multiple buffers:

multi-occur: – Search specified buffers to a string

multi-occur-in-matching-buffers: Allows one to search a subset of one’s open buffers or files specified as a regexp:

Given .* as its first argument, this allows one to search all currently open files for a given regular expression.

Given a prefix argument and .* as its first argument, this allows one to search all currently open buffers for a regular expression.

Also (occur-1 regexp nil buffer-list) can be usefully adapted to search for other things.