bikeNomad -- Good question.

I should probably apologize for the original question to begin with. It arose from a problem I recently encountered with a program that I borrowed and extensively rewrote. It has worked fine with few problems since 6/98 but recently stopped displaying daily and weekly links from the six-month calendar view. I did recently upgrade to Perl 5.6.1 (before anything broke) but am reluctant to jump to conclusions.

I thought that I had brought home my Programming Perl book for the weekend but accidently grabbed Essential System Administration instead. Had I grabbed the right book I wouldn't have needed to ask the question at all.

I narrowed down the problem to the (-s _) clause in question and felt that posting the larger snippet might raise a lot of questions rather than answer a simple one:

   foreach $day (@dow) {
      $TestDate = "$year$cur_month$link_num[$day]";
      if ($Event_Hash{$TestDate} && (-s _)) {
         ### URL to display events for a single day.
         $cal_html = "$EVENT_SUM_URL?Qtype=day&";
         $cal_html .= "BegDate=$year$cur_month$link_num[$day]\">";
         s|^$day |$cal_html${day}${end_anchor} |;
         s| $day$| $cal_html${day}${end_anchor}|;
         s| $day | $cal_html${day}${end_anchor} |;
         $cal_html = "$CAL_LIST_URL_AUTH?date=$date\">";
      }
   }
   if (/</) {
      ### URL to display events for the current week
      $Wk_HTML = "$EVENT_SUM_URL?Qtype=week&" .
                 "BegDate=$year$cur_month$link_num[$First_DOW]&" .
                 "EndDate=$year$cur_month$link_num[$Last_DOW]&" .
                 "WeekNo=$CurrentWk\">";
      $output_pub[$current_line] .= "$_ $Wk_HTML" . "w$end_anchor  ";
   } else {
      $output_pub[$current_line] .= "$_    ";
   }
[download]

I doubt that I wrote the (-s _) clause since I normally try to avoid cryptic code whenever possible. In any case it is unnecessary to perform a -s at this point since all the data read from files is already stored in hashes. The biggest mysteries are how I overlooked it to begin with and why did it work for three years without any noticed problems.

The line in question has been reduced to:

if ($Event_Hash{$TestDate}) {

instead of:

if ($Event_Hash{$TestDate} && (-s _)) {

Thanks to all for responding.