detect changed lines (additions + deletions) in git

detect-changed-lines.sh

#!/usr/bin/env bash

changed_lines_threshold=4
changed_lines=$(git diff --numstat  --pretty="%H"  HEAD^ HEAD | awk 'NF==3 {numlines+=$1+$2} END {printf("%d", numlines)}')

if [[ $changed_lines -gt $changed_lines_threshold ]]]; then
  echo "ERROR: Source code changes detected after last command (${changed_lines} lines). Aborting.";
  exit 1;
fi