git-purge-file

#!/usr/bin/env bash
set -o errexit

# Author: David Underhill
# Script to permanently delete files/folders from your git repository.  To use
# it, cd to your repository's root and then run the script with a list of paths
# you want to delete, e.g., git-delete-history path1 path2
#
#  retrieved from: http://dound.com/2009/04/git-forever-remove-files-or-folders-from-history/
#

if [[ $# -eq 0 ]]; then
  echo 'You must specify a file/directory to purge from your git history'
  exit 1
fi

# make sure we're at the root of git repo
if [[ ! -d .git ]]; then
  echo 'Error: must run this script from the root of a git repository'
  exit 1
fi

# remove all paths passed as arguments from the history of the repo
# shellcheck disable=SC2124
files=$@
git filter-branch --index-filter "git rm -rf --cached --ignore-unmatch $files" HEAD

# remove the temporary history git-filter-branch otherwise leaves behind for a long time
rm -rf .git/refs/original/ && git reflog expire --all && git gc --aggressive --prune