How to ignore some differences in diff command?

Question

diff has an option -I regexp, which ignores changes that just insert or delete lines that match the given regexp. I need an analogue of this for the ca

Answer 1

Improving upon the earlier solution by John Kugelman:

diff <(sed 's/ab[XY]d/abd/g' file1) <(sed 's/ab[XY]d/abd/g' file2)

is probably what you may be looking for! This version normalizes the specific change on each line without deleting the line itself. This allows diff to show any other differences that remain on the line.