use strict; use warnings; use Data::Dump::Streamer; my %firstLines; my @lines; while () { chomp; my ($data, $type) = /(.*)\s+TYPE:\s+(\w+)$/; next if ! defined $type; # ignore malformed line if (exists $firstLines{$data}) { $lines[$firstLines{$data}] .= ", $type"; } else { $firstLines{$data} = @lines; push @lines, $_; } } print join "\n", @lines; __DATA__ MCAT: 0xf30cbe01 PCAT: 0xcda2b409 LMAT: 0x00100000 TYPE: KA0 MCAT: 0xcc3fbed1 PCAT: 0x000fb109 LMAT: 0x00000800 TYPE: KA1 MCAT: 0xeeccbe01 PCAT: 0xcda2b409 LMAT: 0x00100000 TYPE: KA1 MCAT: 0xf30cbe91 PCAT: 0xafaddd09 LMAT: 0x00040000 TYPE: KA0 MCAT: 0xeeecbe01 PCAT: 0xcda2b409 LMAT: 0x00100000 TYPE: KA0 MCAT: 0xcc000331 PCAT: 0x000fb109 LMAT: 0x00000800 TYPE: KA1 MCAT: 0xe554be01 PCAT: 0xcda2b409 LMAT: 0x00100000 TYPE: KA1 MCAT: 0xf30cbe91 PCAT: 0xafaddd09 LMAT: 0x00040000 TYPE: KA1 #### MCAT: 0xf30cbe01 PCAT: 0xcda2b409 LMAT: 0x00100000 TYPE: KA0 MCAT: 0xcc3fbed1 PCAT: 0x000fb109 LMAT: 0x00000800 TYPE: KA1 MCAT: 0xeeccbe01 PCAT: 0xcda2b409 LMAT: 0x00100000 TYPE: KA1 MCAT: 0xf30cbe91 PCAT: 0xafaddd09 LMAT: 0x00040000 TYPE: KA0, KA1 MCAT: 0xeeecbe01 PCAT: 0xcda2b409 LMAT: 0x00100000 TYPE: KA0 MCAT: 0xcc000331 PCAT: 0x000fb109 LMAT: 0x00000800 TYPE: KA1 MCAT: 0xe554be01 PCAT: 0xcda2b409 LMAT: 0x00100000 TYPE: KA1