use autodie;
use Fcntl qw[:DEFAULT :seek];
sysopen my $fh, "/tmp/text.index", O_RDWR | O_CREATE, 0666;
my $count = <$fh> || 0;
seek $fh, 0, SEEK_SET;
truncate $fh;
print $fh $count + 1;
close $fh;