Example of script to automatically stash updates, checkout and merge a branch and then commit the changes

stash_merge_commit_push.sh

#!/bin/bash
set -o errexit # Exit on error
git stash save 'Before deploy' # Stash all changes before deploy
git checkout deploy
git merge master --no-edit # Merge in the master branch without prompting
npm run build # Generate the bundled Javascript and CSS
if $(git commit -am Deploy); then # Commit the changes, if any
  echo 'Changes Committed'
fi
git push heroku deploy:master # Deploy to Heroku
git checkout master # Checkout master again
git stash pop # And restore the changes