+my $saved;
+
+sub iso_date {
+ my @t = localtime(time);
+ return sprintf "%04d-%02d-%02dT%02d:%02d:%02d", $t[5]+1900,$t[4]+1,$t[3],$t[2],$t[1],$t[0];
+}
+
+sub log_tag {
+ my $tag = shift;
+ return if $saved->{tag} or ! $log;
+ my $hash = $rfid->to_hash( $tag );
+ open(my $fh, '>>', $log) || die "$log: $!";
+ print $fh iso_date,",$tag,", $hash->{content}, "\n";
+ close($fh);
+}
+