use strict; use warnings; open (SOMELIST, "somelist") or die "Cannot open file $!\n"; my %sort_data; while (my $record = ) { my @one_line = split(/,/, $record); while (exists $sort_data{$one_line[1]}) { $one_line[1] = "$one_line[1]" . " "; #add a blank for uniqueness } $sort_data{$one_line[1]} = $record; #store it by 2nd column } close (SOMELIST); foreach my $line (sort {$a cmp $b} keys %sort_data) { print "$sort_data{$line}"; }