if(-e $logfile){
  open(IN,"$logfile") or die $!;
  my $line = <IN>;
  close(IN);
  
  my @prev = split(/\s/,$line);
  my $prev = ($prev[1] =~ /^(\d+)\/(\d+)\/(\d+)$/ ? $1*10000 + $2*100 + 1 : 19000101);
  my @inst = localtime(time());
  my $inst = ($inst[5]+1900)*10000 + ($inst[4]+1)*100 + 1;
  
  if($prev < $inst){
    my $bakfile = ($logfile =~ /(\.[^\.]*)$/ ? "$`-$prev$1" : "$logfile-$prev");
    if(-e $bakfile){
      $bakfile = ($logfile =~ /(\.[^\.]*)$/ ? "$`-$prev-$$.tmp" : "$logfile-$prev-$$.tmp");
    }
    rename($logfile,$bakfile) or die $!
  }
}