Git hook to detect if a file changed after a checkout/merge/rebase and show the diff.

gistfile1.sh

#!/usr/bin/env bash
#
# Install into:
# - .git/hooks/post-merge
# - .git/hooks/post-rewrite
# - .git/hooks/post-checkout
#
# And make sure all are executable.
#
# Then change the $file appropriately. Enjoy.

file=".env.sample"

non-sample-file() {
  echo $1 | sed "s/.sample//g"
}

if [[ $(git diff HEAD@{1}..HEAD@{0} -- "${file}" | wc -l) -gt 0 ]]; then
  echo
  echo -e "======> The file \e[33;1m${file}\e[0m changed!"
  echo
  git diff --color HEAD@{1}..HEAD@{0} -- "${file}" | sed 's/^/        /' | tail -n+5
  echo
  echo -e "        Make sure to update your \e[33;1m$(non-sample-file $file)\e[0m."
fi

Thanks! Here is an alternative I made specifically for the West manifest file: https://gist.github.com/tomi-font/e548c23c7d9a321d452dde9c4cc43fa4