$_ = <RECORD>;

##</code><code>##

open(RECORD, "$DATAFILE") or error_page_exit("Could not open datafile");
$_ = <RECORD>;
$val = $_;
close(RECORD);

##</code><code>##

open RECORD, "+< $DATAFILE"

##</code><code>##

flock RECORD, 2; # exclusive lock

##</code><code>##

my $val = <RECORD>; chomp $val; $val++;

##</code><code>##

seek RECORD, 0, 0;

##</code><code>##

print RECORD "$val\n";
close RECORD; # automatically releases the lock