my $Result_summary = "Counts/Summary_table.txt"; open (RESULT_SUMMARY, "+>>$Result_summary") || die "Error opening outfile.$!,stopped"; if ($loop_count == 1 ){ print RESULT_SUMMARY "Reference center\tComparitor center\tArray position\tKnockout no.\tNo. of agreed parameters\tNo. of hits for reference center A\tD_divided_by_E"; }