use strict;
use DB_File::Lock;
use Fcntl qw(O_RDWR O_CREAT);

my $r = shift;
$r->send_http_header("text/plain");

my $dbfile = "/tmp/foo.db";
tie my %dbm, 'DB_File::Lock', $dbfile, O_RDWR|O_CREAT,
    0600, $DB_HASH, 'write';
# assign a random value
$dbm{foo} = ('a'..'z')[int rand(26)];
untie %dbm;

# read the assigned value
tie %dbm, 'DB_File::Lock', $dbfile, O_RDWR|O_CREAT,
    0600, $DB_HASH, 'read';
my $foo = exists $dbm{foo} ? $dbm{foo} : 'undefined';
untie %dbm;

print "The value of foo: [$foo]";