(Delta_Days($3, $months{$1}, $2, $today[2], $today[1], $today[0]) > 30 )? push @log_lines, $line : keep_line($line); 
##</code><code>##

date_diff > 30  ?  move_line : keep_line 
##</code><code>##

if(date_diff > 30) {
  move_line;
} else {
  keep_line;
}