my $exp = Expect->spawn("sftp","username@host") or fatalmsg("$sender Cannot spawn sftp command");

  $exp->expect($timeout,
          ["Password Authentication"],
          ["Are you sure you want to continue connecting", sub {my $self = shift; $self->send("yes\n");}]
          );
  $exp->expect($timeout, ["password:"]);
  $exp->send('xxxxx');
  $exp->expect($timeout, ["sftp>"]);
  my $cmd = "rename path/Long_Filename new_path/Long_Filename";
  $exp->send("$cmd\n");
  $exp->expect($timeout, ["sftp>"]);