Re: Get a git diff without taking index into account

> Some background.
> I'm trying to use Git as an object store for trees.
> I put trees into the repo and can retrieve them.
> I'm having issues with diffing these trees that I retrieve from the repo.
> If I use a "git checkout" the diffs seem to work but if I create the
> tree myself user lower level ls-tree and cat-file commands then the
> diff doesn't work.
> It seems to take the index into account.
>
> Below is a complete working example.
> Should be able to copy / paste line by line.
> I am trying to run the diff of form:
>   git diff [--options] <commit> [--] [<path>...]
> where it says it does a diff from working tree to a commit
>
> Maybe git is interpreting my command as one of the other forms?
> Can someone help me understand what is going on?
>
> #
> # EXAMPLE
> #
>
> # cleanup and create dummy data
> rm -rf /tmp/mydatastore && mkdir -p /tmp/mydatastore
> rm -rf /tmp/test /tmp/test2 && mkdir -p /tmp/test/d1 /tmp/test2
> echo "this is f1" > /tmp/test/f1
> echo "this is f2" > /tmp/test/d1/f2
>
> # create a new branch called test with data from /tmp/test
> git --git-dir=/tmp/mydatastore/.db init --bare
> git --git-dir=/tmp/mydatastore/.db hash-object -w /tmp/test/d1/f2 /tmp/test/f1
> echo -e "100644 blob c837441e09d13d3a0a2d906d7c3813adda504833\tf2" |
> git --git-dir=/tmp/mydatastore/.db mktree --batch
> echo -e "100644 blob
> 11ac5613caf504eec18b2e60f1e6b3c598b085eb\tf1\n40755 tree
> 055f1133fbc9872f3093cca5f182b16611e6789a\td1" | git
> --git-dir=/tmp/mydatastore/.db mktree
> commit_sha=`git --git-dir=/tmp/mydatastore/.db commit-tree -m "initial
> commit" c427094b22e74d1eaeebdc9e49e6790b5b6a706a`
> git --git-dir=/tmp/mydatastore/.db update-ref refs/heads/test $commit_sha
>
> # why does this show diffs?
> git --git-dir=/tmp/mydatastore/.db --work-tree=/tmp/test diff $commit_sha
>
> # after doing a checkout somewhere else it doesn't show any diffs
> git --git-dir=/tmp/mydatastore/.db --work-tree=/tmp/test2 checkout test .
> git --git-dir=/tmp/mydatastore/.db --work-tree=/tmp/test diff $commit_sha
>
> # remove the index and it shows diffs again
> rm /tmp/mydatastore/.db/index
> git --git-dir=/tmp/mydatastore/.db --work-tree=/tmp/test diff $commit_sha
>
> # it was my understanding from "git help diff" that this form of diff
> is supposed to
> # compare a work tree against a commit or branch and not take into
> account the index.
> # Clearly it takes into account the index because we get different
> results with and without it