$exp->expect($timeout,
              [ qr/username: /i, sub { my $self = shift;
                                       $self->send("$username\r");
                                       exp_continue; }],
              [ qr/password: /i, sub { my $self = shift;
                                       $self->send("$password\r");
                                       exp_continue; }],
              $shell_prompt);