johngg@shiraz ~/perl/Monks $ perl -Mstrict -Mwarnings -E ' open my $inFH, q{<}, \ <[ 0 ] => [ split m{-}, $_->[ 1 ] ] } map { [ split ] } <$inFH>; foreach my $key ( sort keys %hash ) { say qq{$key $_} for @{ $hash{ $key } }; }' abcd 723 abcd 724 abcde 552 abcde 554 abcde 553 abcdef 756