sub work_with_file {
    my ( $filename, $fh, $hash) = @_;
.....
.....
$hash->{$dt} = $lines if $errorFound;
}

work_with_file($_, $fh, \%hash);

foreach my $key (sort keys %hash) {
                            print $fh "$key:\n$hash{$key}\n";  
                            }