       copyfile   ?-bytes  num|-maxbytes  num?  ?-translate?
              fromFileId toFileId
              Copies  the  rest  of  the  file specified by from-
              FileId, starting from its current position, to  the
              file  specified by toFileId, starting from its cur-
              rent position.  By default, newline translation  is
              disabled for the duration of the copy.

              If  -bytes is specified, then num bytes are copied.
              If less than num bytes are available, an  error  is
              returned.   If  -maxbytes  is  specified,  then num
              bytes are copied but no error is returned  if  less
              are available.

              If  -translate  is specified, then newline transla-
              tion will not be disabled for the copy.

              The command returns the number of bytes  that  were
              copied.

              The -bytes option is particularly useful for mixing
              binary data in with ASCII commands  or  data  in  a
              data stream.

              This command is provided by Extended Tcl.
