Magento - core code pre commit hook

#!/usr/bin/env bash

set -eu

declare -a file_patterns=('app/code/core' 'app/Mage.php$' '^index.php$')

exit_status=0
while read x file; do
  for file_pattern in ${file_patterns[@]}; do
    if [[ $file =~ $file_pattern ]]; then
        echo "Core change detected: $file" >&2
        exit_status=1
    fi
  done
done < <(git diff --cached --name-status)

exit $exit_status;