Online Help:

Usage: /vol/vssp/local/trees/amma-4/linux/bin/doFastFourierTrans2d [options] 
   -optload () [] Load options from a file.  
   -optsave () [] Save options to a file.  
   -i () [(null)] input file 
   -o () [(null)] output file 
   -help (TRUE) [FALSE] Print usage information.