print this help
erb3.3 [switches] [var=value...] [inputfile]
  -x               print ruby script
  -n               print ruby script with line number
  -v               enable verbose mode
  -d               set $DEBUG to true
  -r library       load a library
  -E ex[:in]       set default external/internal encodings
  -U               set default encoding to UTF-8
  -T trim_mode     specify trim_mode (0..2, -)
  -P               disable ruby code evaluation for lines beginning with %
  var=value        set variable