my @a = ("1-1-2", "6-1-2", "3-1-4");
my @b = sort { 
   (split /-/, $a)[0] <=> (split /-/, $b)[0] &&
   (split /-/, $a)[1] <=> (split /-/, $b)[1] &&
   (split /-/, $a)[2] <=> (split /-/, $b)[2]
} @a; 
print "@b\n";