sub back_up_file {

my ($index, $index_backup) = @_;    

    # open the necessary files needed for reading and writing
    open (INDEX, "<$index") or die &show_error ("Unable to open $index: $!");
    open(BACKUP, ">$index_backup") or die &show_error ("Unable to open $index_backup: $!");

    # write the existing file into the backup
    while (<INDEX>) {
	print BACKUP "$_";
    }

    # close the files
    close (INDEX);
    close (BACKUP);
}

# shows the error returned inside of the browser - easier debuging
sub show_error {

   print "Content-type: text/html\n\n";
   print "This is the error: <h1>$_[0]</h1>";

    exit(0);   

}