#!/usr/bin/perl
  use BerkeleyDB;

  my $file = shift || die "usage: $0 file";

  %hash = ();
  my $db = tie %hash, 'BerkeleyDB::Hash', -Filename => $file, 
      -Flags => DB_RDONLY, -Property => DB_DUP | DB_DUPSORT
    or die "can't read file '$file': $!";

  my $ref = $db->db_stat;
  print "db info: \n", map{"  - ${_}: ".$ref->{$_}.$/} keys %$ref;

  print "db contains ", scalar(keys %hash), " entries\n";
  print map { "  $_ => $hash{$_}\n" } sort keys %hash;

##</code><code>##

  #!/usr/bin/perl
  use DB_File;

  my $file = shift || die "usage: $0 file";

  %hash = ();
  tie %hash, 'DB_File', $file, O_RDONLY, 0666, DB_HASH
    or die "can't read file '$file': $!";

  print "$file has ", scalar(keys %hash), " entries\n";
  print map { "  $_ => $hash{$_}\n" } sort keys %hash;

##</code><code>##

  type parameter is not a reference at /usr/lib/perl5/5.6.1/i386-linux/DB_File.pm line 262.