I have QGIS/GRASS installation and I would like to do my process workflow through shell in Ubuntu. It is raster vectorisation -> selection by value -> saving as shp. I have done first step by gdal command in shell. I have copied command from gui tool where it was shown. But I do not know how to access GRASS module v.extract from shell. Is there a specific command how to access these GRASS modules in QGIS processing tool through shell ?
I would like to access more than just this modul so I would like to know if it is possible or I have to use python scripts or I have to install GRASS standalone to use modules through shell.