git hook to run a command after `git pull` if a specified file was changed

post-merge

#!/usr/bin/env bash
# MIT © Sindre Sorhus - sindresorhus.com

# git hook to run a command after `git pull` if a specified file was changed
# Run `chmod +x post-merge` to make it executable then put it into `.git/hooks/`.
 
changed_files="$(git diff-tree -r --name-only --no-commit-id ORIG_HEAD HEAD)"
 
check_run() {
	echo "$changed_files" | grep --quiet "$1" && eval "$2"
}
 
# Example usage
# In this example it's used to run `composer install` if composer.lock changed.
check_run composer.lock "hash composer 2> /dev/null && composer install || echo -e '\e[1m\e[30m\e[43mcomposer.lock changed, please run a composer install\e[0m'"