use LWP::UserAgent;
$ua = new LWP::UserAgent;

# Create a request
my $req = new HTTP::Request GET => "http://www.craigslist.org/sfo/$categories[$i]";

# Pass request to the user agent and get a response back
my $res = $ua->request($req);

# Check the outcome of the response
if ($res->is_success) {
  print $res->content;
} else {
  print "Bad luck this time\n";
}