ssh terminal settings

[Ashish Mahamuni]

I am doing some automation stuff with freebsd.
on my local machine I am using Net::SSH::Expect (perl library) to run
commands on FreeBSD machine.

The problem is when I execute commands on FreeBSD, I am not able to get the
output of that command on my local machine.
All I am getting is remote shell as a output.

Same script work perfectly if I run it against linux target.

my $ssh = Net::SSH::Expect->new (
    host=>"172.18.28.104",
    user=>"root",
    password=> "root",
       timeout=>5,
       raw_pty=>1
);

$ssh->login();
        my $out = $ssh->exec("ps -aux");
        print $out; //Here I expect complete ps output, which is not working
for FreeBSD.

Is there any terminal setting that I have to do to achieve this?
How does shell gets allocated when we start ssh session?

--Ashish