GRUNT install on OSX

First off, make sure you installed yarn like described here .

In your Terminal app navigate to the folder that you cloned the TYPO3 source into. Switch into the Build folder and run

yarn install

This will install Grunt as well a s couple of Task plugins we use in the TYPO3 core. To make sure grunt is running, run

grunt css

This will run all registered tasks defined in the TYPO3 core.