$file_data =~ s/\n\n+/\n/gs;

##</code><code>##

  # Suggest using scalar filehandles and checking to
  # see if open succeeded...
  open( my $my_filehandle, $file ) || next;
  # possibly: || die "Can't open file: $!";

  local $/ = undef; # tell perl not to stop reading at newline
  my $file_data = <$my_filehandle>;
  close $my_filehandle;

  # process $file_data
  # etc...

##</code><code>##

$file_data =~ s/\n[\s\n]+/\n/gs;

##</code><code>##

$ perl -ni -e 'print if /\S/' *.shtml