How to apply a Git patch to a file with a different name and path?

Question

I have two repositories. In one, I make changes to file ./hello.test. I commit the changes and create a patch from that commit with git format-patch -1 HE

Answer 1

I understand the two files are exactly the same in your situation, thus the patch is likely to succeed.

However, in case you want to apply a patch to a similar, but not exactly the same file, or you want to do an interactive patching, you will use three way merge.

Say you modified File A, let's denote A~1 as the previous version, and you want to apply the diff between A~1 to A to File B.

Open a three way merge tool, for instance Beyond Compare, the path of left panel is A, middle panel is the common ancestor so the path is A~1, the path of right panel is B. Then, the lower panel shows the result of applying the diff between A~1 to A to File B.

The following figure illustrates the idea.