use strict; use warnings; use List::MoreUtils qw/natatime/; my $it = natatime 5, ; while ( chomp( my @lines = $it->() ) ) { my $letter = 'A'; my $acctNum = do { $lines[0] =~ /\s+(\d+)\s+(\d+)/; $1 . $2 }; push @lines, " acctnum=$acctNum"; print for map { s/\s+/$letter++ . ' '/e; "$_\n" } @lines; } __DATA__ Place your data here...