System Database Access

1. Here's one way to do that:

   $: = " "; while (@pw = getpwent) {
    ($user, $gid, $gcos) = @pw[0,3,6]; ($real) = split /,/, $gcos; $real{$user} = $real; $members{$gid} .= " $user"; ($last) = (split /\s+/, $real)[-1]; $last{$user} = "\L$last";
   }
   while (@gr = getgrent) {
    ($gname,$gid,$members) = @gr[0,2,3]; $members{$gid} .= " $members"; $gname{$gid} = $gname;
   }
   for $gid (sort by_gname keys %gname) {
    %all = ();
   for (split(/\s+/, $members{$gid})) {
    $all{$_}++ if length $_;
   }
   @members = (); foreach (sort by_last keys %all) {
    push(@members, "$real{$_} ($_)");
   }
   $memberlist = join(", ", @members); write;
   }
   sub by_gname {
    $gname{$a} cmp $gname{$b};
   }
   sub by_last {
    ($last{$a} cmp $last{$b}) || ($a cmp $b);
   }
   format STDOUT = @<<<<<<<< @<<<<<<<< ^<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< $gname{$gid}, "($gid)", $memberlist ~~ ^<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< $memberlist .
   

   Yes, this one needs some explaining.