usage: /usr/bin/gtf x y refresh [-v|--verbose] [-f|--fbmode] [-x|--xorgmode]

            x : the desired horizontal resolution (required)
            y : the desired vertical resolution (required)
      refresh : the desired refresh rate (required)
 -v|--verbose : enable verbose printouts (traces each step of the computation)
  -f|--fbmode : output an fbset(8)-style mode description
 -x|--xorgmode : output an Xorg-style mode description (this is the default
                if no mode description is requested)