       scanfile ?-copyfile copyFileId? contexthandle fileId
              Scan  the  file  specified by fileId, starting from
              the current file position.  Check all  patterns  in
              the scan context specified by contexthandle against
              it, executing the match commands  corresponding  to
              patterns matched.

              If  the  optional  -copyfile argument is specified,
              the next argument is a file ID to which  all  lines
              not  matched  by any pattern (excluding the default
              pattern) are to be written.  If the  copy  file  is
              specified  with  this  flag,  instead  of using the
              scancontext copyfile command, the file is  disasso-
              ciated  from  the  scan  context  at the end of the
              scan.

              This command does  not  work  on  files  containing
              binary data (bytes of zero).

              This command is provided by Extended Tcl.
