Can I force git diff to treat a file as a copy?

Question

The diff functionality in git has "copy detection"--if it detects that a new file is actually a (possibly modified) copy of an existing file, the diff output shows the differences between the source file and the new file rather than just a bunch of additions from a blank file to the new file.

As far as I can tell, git diff uses some heuristics to detect this situation. Unfortunately it is not detecting a particular new file as a copy of another file because I guess it has changed too much. I'd still like to view the diff as though it were a copy. Is there a way to inform git diff that the new file is a copy of another so that it will do this for me?

Answer 1

git diff (at least my version 1.5.6 does) comes with the switch --find-copies-harder, which does more cpu-intensive copy detection than the regular -C does.

Answer 2

Just want to make sure it was added to the git repo.

Also if you know the original file, why not use diff directly?