#!/usr/bin/perl -w
use strict;
use Fcntl;
use MLDBM qw/DB_File Storable/;

tie my %positions_hash, 'MLDBM', 'positions.db', O_CREAT|O_RDWR, 0640 or die "positions.db: $!\n";

%positions_hash = (
    foo     =>  1,
    bar     =>  2,
    qux     =>  3,
);

untie %positions_hash;