use strict;
use CGI;

my $q = new CGI;

# Set a SESSION persistant cookie. (deleted when browser is closed)
my $cookie = "name=value;path=\";
print $q->header(-cookie => $cookie);

# The cookie value should be some sort of code (encrypted or random), linked
# to a database (or file) variable for validation.

# Read a cookie. And don't forget to verify that it's what you expect.
my $cookie_value = $q->cookie('name');
if ($cookie_value !~ /^\w{23}$/) { print "not a valid cookie\n" }

# Clear a cookie.
# Here you can re-write the cookie with a 'past' date, or simply null it out
# Also clear out the database (or file) variable.
my $cookie = "name=;path=\";
print $q->header(-cookie => $cookie);