#
# create some example data
#
cd /tmp
rm -rf exampledata workspace

mkdir -p /tmp/exampledata/item123
echo "file1 contents" > /tmp/exampledata/item123/file1
echo "file2 contents" > /tmp/exampledata/item123/file2
echo "file3 contents" > /tmp/exampledata/item123/file3
mkdir -p /tmp/exampledata/item123/foo/bar
echo "spam" > /tmp/exampledata/item123/foo/bar/eggs

#
# store that dummy data into a Git repo under /tmp/workspace/.db
#
rm -rf /tmp/workspace && mkdir /tmp/workspace
git --git-dir=/tmp/workspace/.db init
git --git-dir=/tmp/workspace/.db --work-tree=/tmp/exampledata/item123 add .
tree_sha=`git --git-dir=/tmp/workspace/.db --work-tree=/tmp/exampledata/item123 write-tree`
commit_sha=`git --git-dir=/tmp/workspace/.db commit-tree -m "initial storing of item123" $tree_sha`
git --git-dir=/tmp/workspace/.db update-ref refs/heads/item123 $commit_sha

#
# check out a copy of the data we just started tracking
#
mkdir -p /tmp/workspace/iii
git --git-dir=/tmp/workspace/.db --work-tree=/tmp/workspace/iii checkout item123 .

#
# The contents of /tmp/workspace/iii is now exactly the same as /tmp/exampledata/item123
# It has been put in and retreives from a Git repo under /tmp/workspace/.db
#

#
# make a change
#
echo "hello" >> /tmp/workspace/iii/world


# how do I show differences between the contents of /tmp/workspace/iii and
# the tree pointed to by the item123 commit?