Creating a git diff from nothing

Question

I am trying to create a patch file to be used via reviewboard.
It will be the initial patch.

diff -ruN --exclude=.git empty_dir working_dir > mypatch_00.patch works but I am getting a "The selected file does not appear to be a diff." error.

Is there any way to get it working using git-diff or diff? Thank you

Answer 1

If you want to get diff for your initial commit (maybe I misunderstood your question), you can display it using

git show COMMIT

Alternatively to get it as file:

git format-patch -1 COMMIT

Where COMMIT is revision of this commit. If this is your current commit as well, you don't have to specify it at all.

However if your commit is not initial and you want to get full diff for your history, you need to create empty branch first:

git checkout --orphan empty         # Create orphaned branch
git read-tree --empty               # Remove all files from index
git commit --allow-empty -m 'Empty' # Initial commit

Now you can do full diff against empty branch:

git diff empty..master

Answer 2

If you want the full diff from nothing to a particular commit, there is an easier way than in the accepted answer:

empty_tree=$(git hash-object -t tree /dev/null) 
git diff-tree -p ${empty_tree} $MY_COMMIT [${files}...]

The value of ${empty_tree} is always 4b825dc642cb6eb9a060e54bf8d69288fbee4904 but I prefer not to have the magic number in there.

Answer 3

I prefer "empty" as a tag. Simplest way is:

git tag empty $(git hash-object -t tree /dev/null)

Because tag can point to tree-ish directly, without commit. Now to get all files in the working tree:

git diff --name-only empty

Or the same with stat:

git diff --stat empty

All files as diff:

git diff empty

Check whitespaces in all files:

git diff --check empty