and here's a little example of Expect and plain old ssh.

#!/usr/bin/perl
use strict;
use warnings;
$|++;

use Expect;

# a heading for the run 
my $section = shift @ARGV;
my $want_stdout = 0;

unless ( defined $section and length $section ) {
        $section = 'intentionally left blank';
        $want_stdout = 1;
}

my $router = 'rtr_foo';
my $timeout = 20;
my $tmp_log = "/tmp/ssbinfo.$$";
my $real_log = "/home/network/SSB-INFO.LOG";
my $su_pass = 'yeahright';
my $ssh_user = 'automatron';
my $ssh_id = '/home/network/bin/automatron.identity';

my $ssh = '/usr/bin/ssh';

my $ssh_spawn = "$ssh -l $ssh_user -i $ssh_id -x $router";

eval {         # catch failures!!!

my $e = Expect->new()
  or die "No new Expect!\n";

$e->log_stdout(0);   # no logging yet

#$e->debug(2);
#$e->exp_internal(1);  # debug more

# $e->raw_pty(1);       # didn't seem to need these
#$e->stty(qw/raw -echo/);
#$e->slave->stty(qw/raw -echo/);

$e->spawn( $ssh_spawn ) or die "Cannot spawn ssh with: $ssh_spawn : be
+cause $!\n
";
my $ssb_prompt = "SSB0\\(${router} vty\\)# ";
my $root_prompt = "root\@${router}% ";
my $shell_prompt = '% ';
my $rtr_prompt = "${ssh_user}\@${router}> ";

$e->expect( $timeout,
        [ qr/^$rtr_prompt/ => sub {
                my $e = shift;
                $e->send("start shell\n");
                exp_continue; } ],
        [ qr/^$shell_prompt/ => sub {
                my $e = shift;
                $e->send("su\n");
                exp_continue; } ],
        [ qr/^Password:/ => sub {
                my $e = shift;
                $e->send("$su_pass\n");
                exp_continue; } ],
        [ qr/^$root_prompt/ => sub {
                my $e = shift;
                $e->log_file($tmp_log, 'w');  # w for overwrite, just 
+in case
                $e->send("date\n");
                $e->expect($timeout, [ qr/^$root_prompt/ => sub {
                        my $e = shift;
                        $e->send("vty ssb\n"); } ],
                );
                exp_continue; } ],
        [ qr/^$ssb_prompt/ => sub {
                my $e = shift;
                $e->send("set syslog tty disable\n");
                $e->expect($timeout, [ qr/^$ssb_prompt/ => sub { } ],)
+;
                } ],
        [ 'Cannot exec' => sub {
                die "Cannot exec ssh with: $ssh_spawn!\n";
                } ],
) or die "failed getting to the ssb!\n";

# eww! cut-n-paste evil

$e->send("show heap 0\n");
$e->expect($timeout, [ qr/^---\(more\)---/ => sub {
                my $e = shift;
                $e->send("\n");
                exp_continue; } ],
        [ qr/^$ssb_prompt/ => sub { } ],
) or die "failed command 1!\n";

$e->send("show heap 0 accounting pc\n");
$e->expect($timeout, [ qr/^---\(more\)---/ => sub {
                my $e = shift;
                $e->send("\n");
                exp_continue; } ],
        [ qr/^$ssb_prompt/ => sub { } ],
) or die "failed command 2!\n";

$e->send("show heap 0 accounting size\n");
$e->expect($timeout, [ qr/^---\(more\)---/ => sub {
                my $e = shift;
                $e->send("\n");
                exp_continue; } ],
        [ qr/^$ssb_prompt/ => sub { } ],
) or die "failed command 3!\n";

#
# turn off logging
#
$e->log_file(undef);

$e->send("exit\n");
$e->expect($timeout, [ qr/^$root_prompt/ => sub { } ])
  or die "failed exit ssb!\n";

$e->send("exit\n");
$e->expect($timeout, [ qr/^$shell_prompt/ => sub { } ])
  or die "failed exit su!\n";

$e->send("exit\n");
$e->expect($timeout, [ qr/^$rtr_prompt/ => sub { } ])
  or die "failed exit shell!\n";

$e->send("exit\n"); sleep 1;
1 or die "can't screw up exit router!\n";

$e->soft_close();
$e = undef;

# clean up temporary file

use Fcntl qw(:flock);

open(IN, '<', $tmp_log) or die "Can't find $tmp_log\n";
if ( $want_stdout ) {
        *NI = *STDOUT;
} else {
        open(NI, '>>',$real_log)or die "Can't find $real_log\n";
        flock(NI, LOCK_EX);
}
print NI $/;
if ( defined $section and length $section ) {
        print NI "#$/# Begin: ${section}$/#$/";
}
while (<IN>) {
        next if $. == 1 and /^date/;   # just looked ugly
        # next two lines fix up a few syslog messages
        # that make it through before we could turn
        # them off
        next if /^\[/;
        print(NI "SSB0(rtr_foo vty)# "),next if /^SSB0\(rtr_foo vty\)#
+ \[/;
        s/---\(more\)---\r//;  # damn pager
        s/\r//; 
        print NI $_;
}
print NI $/;
if ( defined $section and length $section ) {
        print NI "#$/# End: ${section}$/#$/";
}

close(NI) if !$want_stdout; # unlocks if locked, don't close STDOUT!
close(IN);

};              # end great big eval
if ($@) {
        print "$@";
}

unlink $tmp_log;

exit;
[download]

which was hastily written (probably self evident) to do a couple of logins and run some commands.

$ ssh -l automatron -i /home/network/bin/automatron.identity -x rtr_foo
...
automatron@rtr_foo> start shell
...
% su
Password: ****
...
root@rtr_foo% date
...
root@rtr_foo% vty ssb
.....
SSB0(rtr_foo vty)# set syslog tty disable
...
SSB0(rtr_foo vty)# show heap 0
...
---(more)---
...
SSB0(rtr_foo vty)# show heap 0 accounting pc
...
---(more)---
...
SSB0(rtr_foo vty)# show heap 0 accounting size
...
---(more)---
...
SSB0(rtr_foo vty)# exit
...
root@rtr_foo% exit
...
% exit
...
automatron@rtr_foo> exit