# [...]
if( -e $file ){
    my ($d,$m,$y) = (localtime time)[3..5];
    my $date = sprintf "%02d%02d%04d", $d,$m+1,$y+1900;
    my $new  = 'tttt' . $date . '.bak';
    copy $file, $new;
    unlink $file if -e $new;
}
# [...]