Looking at this code, it already seems that you handle variables. So, let's see if we can get a SSI 'exec' in there, too.

Here is the code I just tested. It is a little different from the original (I removed the prototyping '()' from the function name, and changed the @_[0] to shift) just to make it work in my test.

sub DisplayHTML { 
  $HTMLFileName = shift;
  open(HTMLFNH,"<$HTMLFileName")
    || die "ERROR: Can't open $HTMLFileName: $!";
  print "Content-type:  text/html\n\n";
  while ($HTMLLine=<HTMLFNH>) {
    chomp $HTMLLine;
    $HTMLLine =~ s/(\$[\w\[\]{}']+)/'"'.$1.'"'/gee;
    if ($HTMLLine =~ /(.*?)<!--\s*#exec cmd=\"?(.*?)\"? -->(.*)/) {
      $HTMLLine = $1 . `$2` . $3;
    }
    print "$HTMLLine\n";
  }
  close(HTMLFNH);
}
[download]

It took a little work (on my part - still coming up to speed myself!), but this did test out in my scenario. Let me know if it works for you. I don't know if this is the 'best' way, but it is probably the easiest.

One thing I think I really have to say is that these SSI 'exec's can open a whole world of trouble, so be careful with the code the SSI is running.

D a d d i o