sdiff, you can merge two files interactively based on a
side-by-side -y format comparison (see Showing Differences Side by Side). Use
--output=file (-o file) to specify where to
put the merged text. See Invoking
sdiff, for more details on the
Another way to merge files interactively is to use the Emacs Lisp
emerge. See Emerge in The
GNU Emacs Manual, for more information.