You can certainly start GRASS without the gui: 

    grass64 -text

Furthermore, you can run GRASS in batch mode with actually "starting" the program at all. If you prepare a bash script which sets up the required environment, then you can have GRASS commands run without the GRASS interface at all.
Full details in the [grass wiki][1]


  [1]: http://grasswiki.osgeo.org/wiki/GRASS_and_Shell