## Main program.
    {
        my ($pty, $ssh, @lines);
        my $host = "changeme";
        my $user = "changeme";
        my $password = "changeme";
        my $prompt = '/changeme:~> $/';

        ## Start ssh program.
        $pty = &spawn("ssh", "-l", $user, $host);  # spawn() defined below

        ## Create a Net::Telnet object to perform I/O on ssh's tty.
        use Net::Telnet;
        $ssh = new Net::Telnet (-fhopen => $pty,
                                -prompt => $prompt,
                                -telnetmode => 0,
                                -cmd_remove_mode => 1,
                                -output_record_separator => "\r");

        ## Login to remote host.
        $ssh->waitfor(-match => '/password: ?$/i',
                      -errmode => "return")
            or die "problem connecting to host: ", $ssh->lastline;
        $ssh->print($password);
        $ssh->waitfor(-match => $ssh->prompt,
                      -errmode => "return")
            or die "login failed: ", $ssh->lastline;

        ## Send command, get and print its output.
        @lines = $ssh->cmd("who");
        print @lines;

        exit;
    } # end main program

    sub spawn {
        my(@cmd) = @_;
        my($pid, $pty, $tty, $tty_fd);

        ## Create a new pseudo terminal.
        use IO::Pty ();
        $pty = new IO::Pty
            or die $!;

        ## Execute the program in another process.
        unless ($pid = fork) {  # child process
            die "problem spawning program: $!\n" unless defined $pid;

            ## Disassociate process from existing controlling terminal.
            use POSIX ();
            POSIX::setsid
                or die "setsid failed: $!";

            ## Associate process with a new controlling terminal.
            $tty = $pty->slave;
            $tty_fd = $tty->fileno;
            close $pty;

            ## Make stdio use the new controlling terminal.
            open STDIN, "<&$tty_fd" or die $!;
            open STDOUT, ">&$tty_fd" or die $!;
            open STDERR, ">&STDOUT" or die $!;
            close $tty;

            ## Execute requested program.
            exec @cmd
                or die "problem executing $cmd[0]\n";
        } # end child process

        $pty;
    } # end sub spawn