sudo apt-get install meld
ediff-files3
(for choosing three documents) orediff-buffer3
(for choosing three already-open buffers). You'll get a display screen looking like this:d
org
to go to the following/previous diffs, whileab
will copy the region from barrier a (the leftmost one) to stream c (the center a single), and similarly for other two-letter mixtures ofa
,w
,d
;rb
will restore the area in barrier b. Strike?
for a quick help menu, or read the great guide on diff3 merging in Emacs.