Hi, freesurfer team.
when I check my DTI registration and run the below command:
the bash terminal always tell me 
freeview -v $SUBJECTS_DIR/$subj/mri/orig.mgz \
            lowb.nii:reg=register.dat \
         -f $SUBJECTS_DIR/$subj/surf/lh.white:edgecolor=green \
            $SUBJECTS_DIR/$subj/surf/rh.white:edgecolor=green \
         -viewport coronal