git diff for custom 2 files outside of any repository?

Question

I need git diff functionality for 2 files that I have outside of any repository. Is there a way to do it? Something like git diff --file1 /path/file1.txt --fi

Answer 1

The answer is right in the git diff documentation (though I admit it's easy to miss):

git diff [<options>] --no-index [--] <path> <path>

This form is to compare the given two paths on the filesystem. You can omit the --no-index option when running the command in a working tree controlled by Git and at least one of the paths points outside the working tree, or when running the command outside a working tree controlled by Git.

Your case might fall into the "--no-index is optional" category, but even if it's optional you can still use it, so:

git diff --no-index /path/file1.txt /path/file2.txt

will use Git's diff.

Answer 2

If the two files are really outside of any Git repository, then Git effectively doesn't "know" anything about these files, and so git diff won't work. But, the regular Linux diff command should work. So instead of doing:

git diff /path/to/file1.txt /path/to/file2.txt

do this:

diff /path/to/file1.txt /path/to/file2.txt