#! /usr/bin/perl
use Net::SSH::Expect;

#Preparing for ssh session
my $ssh = Net::SSH::Expect->new (
    host=>"poseidon",
    user=>'testusr',
    timeout=>10,
    raw_pty=>1,
    password=>'wel123go',
    log_file=>"log.txt"
);

#Logging in to the session
$ssh->login();
print "Logged in \n";

# Commands executed
$ssh->exec("stty raw -echo");
$whoami=$ssh->exec("whoami");

print "\$whoami : ",$whoami,"\n";  

$ssh->send("su -");
$ssh->waitfor('Password:\s*\z', 1) or die "prompt 'Password' not found after 1 second";

my $pass = 'passw0rd';

$result =  $ssh->send($pass);

print "\$result : ",$result,"\n";

$whoami=$ssh->exec("whoami");   

print "\$whoami : ",$whoami,"\n";  # Expect to see root

#closing the session
$ssh->close();