man/examples/ex_grassGUI.r

In adamlilith/fasterRaster: Faster Raster and Spatial Vector Processing Using 'GRASS GIS'

if (grassStarted()) {

# Starting the GRASS GUI and making changes to rasters or vectors can "break"
# the GRasters and GVectors they are associated with in R.
if (interactive() & FALSE) grassGUI()

}