sub checkdbm {
  my $hashref=shift;
  my $key=shift;
  
  if (-f "$key-dbm.db") {
    return;
  }

  my %hash;

  tie (%hash,'NDBM_File',"$key-dbm",O_RDWR|O_CREAT,0640);

  $hashref->{$key}=\%hash;
}