>perl -wMstrict -le "my @unsorted = (1, 10, '-', 2, -3, 20, '-', '-', 3, 0, 2, 11, 8, 7); ;; my @sorted = sort numeric_ascending_with_dash_leftmost @unsorted; print qq{@sorted}; ;; @sorted = sort { -numeric_ascending_with_dash_leftmost() } @unsorted; print qq{reversed: @sorted}; ;; print qq{still unsorted: @unsorted}; ;; sub numeric_ascending_with_dash_leftmost { return $a eq '-' ? -1 : $b eq '-' ? 1 : $a <=> $b ; } " - - - -3 0 1 2 2 3 7 8 10 11 20 reversed: 20 11 10 8 7 3 2 2 1 0 -3 - - - still unsorted: 1 10 - 2 -3 20 - - 3 0 2 11 8 7