Vimdiff - How to extract similar lines in files and output them to a file.

Answer 1

You could use regular diff to get the output if you have it installed:

diff  --unchanged-line-format='%L' --old-line-format='' \
  --new-line-format='' a.txt b.txt

You would run that from the command line on Linux. Or from within Vim you would run it by typing :! first as follows:

:!diff  --unchanged-line-format='%L' --old-line-format='' \
  --new-line-format='' a.txt b.txt