Watch files and execute command upon change

Find yourself executing the same command over and over again after applying changes to certain files? Pywatch will be you best friend!

Meet pywatch: a cool little app that watches directories and files. Whenever it finds a file that changed, it executes the command you provided.

TL;DR

As an example; I use this to build a Docker image whenever I save a change to my Dockerfile.

pywatch "docker build . -t pauledenburg/behat" Dockerfile

Or execute tests whenever I make a change to one of the sourcefiles.

commandToExecute='docker exec -i hangman_app_1 behat -c tests/behat/behat.yml'
find ./tests -name "*.php" -o -name "*.feature" \
  | xargs pywatch "$commandToExecute"

This keeps an eye on all *.php and *.feature files under ./tests.

When one of these files changes, it executes $commandToExecute which resolves to executing behat in a Docker container.

Install

Download the pywatch app from github: https://github.com/cmheisel/pywatch.

Then unzip and install with python.

unzip pywatch-master.zip
cd pywatch-master
sudo python setup.py install

Advanced usage

Nice one: run tests when files change and create a Mac notifier whenever the tests fail.

This way you can keep the tests running in the background and you’ll be notified whenever a test failed.

find src tests -name "*.php" -o -name "*.feature" \
  | xargs pywatch "./dev test phpunit" \
  | grep "([0-9]* failed)" \
  | sed -e 's/.*(\([0-9]* failed\)).*/\1/' \
  | while read failure; 
    do 
      terminal-notifier -message "Test output: $failure" -title "Tests Failed!"
    done