use strict;
use DB_File;

my %sorted;
$DB_BTREE->{compare} = sub {$_[1] cmp $_[0]};
tie (%sorted, 'DB_File', undef, O_RDWR|O_CREAT, 0640, $DB_BTREE) or die $!;

%sorted = 1..30;
print map "$_\n", keys %sorted;