git_filter_branch.sh

#!/usr/bin/env bash

set -e

FILES_TO_PRUNE="path_to_large_file_from_root_of_repo"

catch_error () {
  local cmd_name=$1
  local ret_code=$2
  if [ $ret_code -ne 0 ]; then
    echo "Problem found, please examine ${cmd_name} output."
    exit 1
  else
    echo "Command ${cmd_name} completed without errors."
  fi
}

go_up_one_directory () {
  cd ..
}

git_filter_unwanted_files() {
  local files_to_prune=$1 
  printf "Filtering this git repo...\n"
  git filter-branch --prune-empty --index-filter \
    "git rm --cached --ignore-unmatch ${files_to_prune}" \
    --tag-name-filter cat -- --all
  catch_error "git filter-branch" $?
}

git_clone_filtered_repo () {
  local working_dir=$1
  local new_repo="$(basename $working_dir)-cleaned"
  printf "\nCloning into a new repo...\n"
  git clone --no-hardlinks file://$working_dir $new_repo
  catch_error "git clone" $?  
}

echo -n 'Are you sure you want to do git filter-branch on this repo? (y/n) '
read input

case $input in
  [Yy])
    git_filter_unwanted_files $FILES_TO_PRUNE
    go_up_one_directory
    git_clone_filtered_repo $OLDPWD
  ;;
  *)
    echo "Exiting."
    exit 1
  ;;
esac