I'm not sure where the right place here on perlmonks is to share coding examples. But.. after much flailing about i've managed to tame ssh2 {and auth and all of that} and I have a working sub that does exactly what I want and I thought I'd share. My approach to using the SSH2 connection is to send commands, poring over the output of each to decide what to do next until I"m done.

# NB: you can only do one command on a channel so we get the channel
##  do the command give back the output then close the channel   Note 
+that the command
##  must be a fully "shell punctuated and escaped" 
sub docmd
{   my $chan = $ssh2->channel() or $ssh2->die_with_error ;
    $chan->exec("($_[0]) 2>&1") ;   # 
    my $out = "";
    while (!$chan->eof)
    {   my $buffer = "";
        my $bytes = $chan->read($buffer, 100) ;
        $ssh2->die_with_error if $bytes < 0 ;
        $out .= $buffer ;
    }
    return $out ;
}
[download]

and I tested it with:

print docmd("cd tmp; ls") ;
print docmd("cd bin; ls") ;
$ssh2->disconnect() ;
[download]

and I confess that I was amazed that it worked.