Perl script to check if tickets for a specific London 2012 Olympics session are currently available

ticket_watch.pl

#!/usr/bin/perl -w
 
     use Getopt::Std;
  
     # Define the address the alerts should come from
 
     $monitor_email              = "monitor@monitor.com";
     $monitor_url                = "http://www.tickets.london2012.com/browse?form=session&tab=oly&sessionCode=";
 
     # Define global variables
     $curl_executable            = "/usr/bin/curl";
     $mail_executable            = "/usr/sbin/sendmail";
     $OPT_STRING                 = 'he:';

     # Start program
     &main();
 
 
 sub main {
 
   # Read in the options
   getopts( "$OPT_STRING", \%opt ) or usage();
 
   # Set variables
   my $url_header        = "";
   my $url_body          = "";
   my $email_address     = "";
   my $session_code               = $ARGV[0];

   # Determine options
   usage() if $opt{h};
   usage() if !$opt{e};
   
   # Define more variables
   $email_address = $opt{e};

   # Monitor URL
   my $session_url = $monitor_url . $session_code;
   $url_body = `$curl_executable -s "$session_url"`;

   if ($url_body =~ /Continue1/) { &send_alert($email_address, $session_url, $session_code);}
 }
 
 sub send_alert {
 
   my ($email_address,$url,$session_code) = @_;
 
   # Create timestamp
   my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime(time);
   $year = $year + 1900;
   $mon  = $mon + 1;
   my $time_stamp = $year."-".$mon."-".$mday." ".$hour.":".$min.":".$sec; 
  
   my $email_content = $session_code ." tickets available at ". $time_stamp . "\n" . $url . "\n";

   unless(open (MAIL, "| /usr/sbin/sendmail -t")) {
         print "error.\n";
         warn "Error starting sendmail: $!";
   }  
   else{
         print MAIL "From: " . $monitor_email . "\n";
         print MAIL "To: " . $email_address . "\n";
         print MAIL "Subject: " . $session_code . " AVAILABLE!\n\n";
         print MAIL $email_content;
         close(MAIL) || warn "Error closing mail: $!";
         print ("$email_content");
   }
 }
 
 sub usage {
 
     print "Usage: ticket_watch.pl -e <email address> <session code>\n\n";
     exit;
 
 }