use Apache2::Request;
use Apache::Session::File;
use warnings;

#read cookie if this is an running session

 my $r = Apache2::RequestUtil->request;
 my $cookie = $r->headers_in('Cookie');

#Create a session object based on the cookie 

my %session;
tie %session, 'Apache::Session::File', $cookie, {
    Directory => '/tmp/plsessions',
    LockDirectory   => '/tmp/plsessionlock',
 };

# if a new session, give it cookie back

my $session_cookie = "SESSION_ID=$session{_session_id};";
 $r->headers_out("Set-Cookie" => $session_cookie);