Example script that uses a Git repo as a vehicle for storing content from a tarball as a new commit

tarball-to-commit.sh

#!/bin/bash

# This script demonstrates using a Git repo as a vehicle for storing content
# from a tarball. It creates new commits, children of a given repo's current
# HEAD, which contain exactly the contents of a given tarball. No consideration
# is given to the prior commit's contents when constructing the new commit.

# Basic usage message if incorrect number of params passed
if [ $# -ne 2 ]; then
  echo "Usage: ${0} <path-to-tarball.tar.gz> <[email protected]>"
  exit 1
fi

tarball="${1}"
remote="${2}"

# Stop immediately if anything goes wrong. Be verbose.
set -e
set -x

# Start by creating a temporary working directory, and ensure it is removed on
# script exit.
tmpdir="$(mktemp -d)"
trap "rm -rf '${tmpdir}'" EXIT

# The remainder of the work occurs inside the tmpdir.
pushd "${tmpdir}"
  # In the working directory, create a NEW git repo.
  git init .

  # Add the upstream remote, fetch it, and determine the current HEAD commit
  # of the default branch.
  git remote add upstream "${remote}"
  git fetch upstream --depth 1
  remote_branch="$(git remote show upstream | awk '/HEAD/ {print $3}')"
  remote_parent="$(git rev-parse "refs/remotes/upstream/${remote_branch}")"

  # Extract the tarball to the working directory and stage all of its contents
  # to the git index. Do not commit. We will construct the commit manually.
  tar -xzf "${tarball}"
  git add -A

  # Construct a new commit object with the staged content as the tree, and the
  # upstream's default HEAD commit as the parent.
  tree=$(git write-tree)
  commit=$(git commit-tree "${tree}" -p "${remote_parent}" <<<"Set contents to $(basename "${tarball}")")

  # Push the constructed commit to the remote's default branch
  git push upstream "${commit}:${remote_branch}"
popd

# The EXIT trap will handle deleting the temporary working directory