http://somedomain.com/cgi/register.cgi?login=$login&id=$user->{'id'}&e
+mail=$user->{'email'}
[download]

In the above code, I am passing an argument email with some email address fetched from facebook profile. However, when I dump those vars, I am not getting the value of email.

Moreover, using Facebook::Graph::Query, we can get first_name, last_name, name, email by specifying them as fields

Where do you dump the vars, in register.cgi or in the script accessing the URL? Could you provide some sample code that reproduces the problem? I know what I mean. Why don't you?

Taking a guess based on the information you've provided so far: are you perhaps looking for URI?

use URI;
my $uri=URI->new("http://somedomain.com/cgi/register.cgi");
$uri->query_form(login=>"somelogin", id=>12345, email=>'foo@bar.com');
print "$uri\n";
__END__
http://somedomain.com/cgi/register.cgi?login=somelogin&id=12345&email=
+foo%40bar.com
[download]

How to send a redirect with CGI is in its documentation, with sample code ("Generating a Redirection Header"). If you do that, take care not to print out a regular header() as well.

Thank you for your inputs. However, I have nearly 10+ fields to be sent and I don't think it makes any sense to send it via URL. Here is the code I'm working on....

#!/usr/bin/perl

use strict;
use HTTP::Request::Common;
use CGI;
use Facebook::Graph;
use Data::Dumper;

my $APP_ID = 'SOME_ID';
my $SECRET = 'SOME_SECRET_CODE';
my $POSTBACK_URL = "http://goto.this.domain/postback.pl";

my $fb = Facebook::Graph->new(
    app_id          => $APP_ID,
    secret          => $SECRET,
    postback        => $POSTBACK_URL,
);

my $q = new CGI;
my $params = $q->Vars;

my $code = $params->{'code'};

$fb->request_access_token($code);

my $token = $fb->access_token;
$fb->request_extended_access_token($token);

my $user = $fb->fetch('me');

#register the facebook data into my site to create a new profile;
my $login = $user->{'name'};
$login =~ s/\s//g;

my $sarah_bownds = $fb->query->find($user->{'id'})
    ->select_fields(qw(id name email))
    ->request
    ->as_hashref;
    
my $default_picture =  $fb->picture($user->{'id'})->get_square->uri_as
+_string;

my %register = (
    login => $login,
    firstname => $user->{'first_name'},
    lastname => $user->{'last_name'},
    email => $user->{'email'},
    action => 'register',
    id => $user->{'id'},
);

print $q->redirect("http://goto.this.domain/cgi/register.cgi?login=$lo
+gin&id=$user->{'id'}&email=$user->{'email'}&msg=201&args=$sarah_bownd
+s");
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