How to create a contour map: asking GRASS for help - part I

As you probably know, JGrass can execute GRASS command, which makes it a really powerfull funbox.

So what if I want to extract a shapefile of contour lines from a DTM?

def outputName = "contours"
def outFolder = "/Users/moovida/TMP/"
def inputDem = "bacino_chiese_pit"
grass r.contour --o input=$inputDem output=$outputName step=250
grass v.out.ogr input=$outputName type=line dsn=$outFolder olayer=$outputName layer=1 format=ESRI_Shapefile
grass g.remove vect=$outputName

And we go from:


through:


to the needed layer: