Run Rubocop using the project settings on modified files in your Git repository. Store this in `.git/hooks/pre-commit` to reject commits with style offsenses.

gistfile1.sh

#!/bin/bash
git diff --cached --name-status --diff-filter=ACM | awk '/\.rb$/ { print $2 }' | xargs rubocop -f s
exit_code=$?
if [[ $exit_code != 0 ]] ; then
  echo 'Your commit was rejected because Rubocop found style guide violations.'
  echo 'Run `rake rubocop` to test your code and inspect the offenses Rubocop'
  echo 'has found.'
  echo
  echo 'If you really, REALLY want to commit this code, skip your pre-commit'
  echo 'hooks with `git commit --no-verify`.'
fi
exit $exit_code