Seems easy to me...

use Net::Telnet ();
    $t = new Net::Telnet (Timeout => 10,
                          Prompt => '/bash\$ $/');
    $t->open("sparky");
    $t->login($username, $passwd);
    @lines = $t->cmd("who");
    print @lines;
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although I would use ssh if at all available. Expect is too generic for this task. You have to rewrite all of the status tests for the login/disconnect and all the other stuff like what if the telnet bin segfaults while you are running our control script. Net::Telnet was made for this task and is damn good at doing it.