WARNING TO MAC USERS - WAIT UPDATING TO EL CAPITAN (OS X 10.11)
I've had reports of GRASS not running for users updating to El Capitan. There is a possible workaround, but it is cumbersome and not guaranteed to work. I recommend that you do wait to update while we try to solve this.
I've also heard that El Capitan breaks R.
C. Michael Barton
Director, Center for Social Dynamics & Complexity
Professor of Anthropology, School of Human Evolution & Social Change
Head, Graduate Faculty in Complex Adaptive Systems Science