Canela inspired me to contribute a little perl script I wrote to monitor my webserver.

Here is how you use it:

Code:
# monitor-website.pl -e my@email-address.com http://www.website.com
  1. The "-e" is the email address that should receive notifications.
  2. You can also use the "-s" option to look for a specific string on the web page. The string should be in quotes, but will work without them if there ar no spaces or special characters.
  3. I purposely didn't use any perl modules so that it would work on any system.
  4. It works first by using "curl -I" to see if the site returns a "200 OK" message in the page header, and if it does, it will use curl to get the entire page searching for </html> at the end unless "-s" specifies some other string.
  5. monitor_email is the email address the warning email appears to come from in the envelope.
  6. If your web page does a redirect, for example from http://www.website.com/about to http://www.website.com/about/ the script will fail as it only looks for the "200 OK" code, not the "302" redirect code. So first run "curl -I URL" first to see if a 200 OK is returned.
  7. Here is the wiki page for future modifications.


It is not heavy duty, but should work well for a personal site. Let me know if it works OK for you!

Code:
 #!/usr/bin/perl
 
     use Getopt::Std;
  
     # Define the address the alerts should come from
 
     $monitor_email              = "monitor@monitor.com";
 
     # Define global variables
     $curl_executable            = "/usr/bin/curl";
     $mail_executable            = "/usr/sbin/sendmail";
     $OPT_STRING                 = 'hs:e:';
 
     # 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 $url               = $ARGV[0];
   my $valid_string      = "</html>";
 
   # Determine options
   if ($opt{s}) { $valid_string = $opt{s};}
   usage() if $opt{h};
   usage() if !$opt{e};
   
   # Define more variables
   $email_address = $opt{e};
 
   # Monitor URL
   $url_header = `$curl_executable -I -s $url`;
 
   if ($url_header =~ /200 OK/){
         $url_body = `$curl_executable -s $url`;
         if ($url_body =~ /$valid_string/){
                 #print ("$url_header\n");
         }
         else{
                 &send_warning($email_address, $url);
         }
   }
   else{
         &send_warning($email_address, $url);
   }
 
 }
 
 sub send_warning {
 
   my ($email_address,$url) = @_;
 
   # 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 = $url ." failure at ". $time_stamp . "\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: Website URL Monitor Failure\n\n";
         print MAIL $email_content;
         close(MAIL) || warn "Error closing mail: $!";
         print ("$email_content");
   }
 }
 
 sub usage {
 
 print STDERR << "EOF";
 
     This program monitors HTTP URLS
 
     usage: $0 [-h] [-s "string"]
 
      -h                   : This (help) message
 
      -e email-address     : The email address that should be alerted.
 
      -s                   : Unique string found on the web 
                             page that proves it is working correctly
 
     example: $0 -s -e email-address URL
 
 
 EOF
     exit;
 
 }