sub open_db
{
    my ($dsn, $dbh, $defaults);
    
    $defaults = (defined $opts{defaults} && -f $opts{defaults})
              ? $opts{defaults}
              : (-e $ENV{HOME}.'/.my.cnf')
              ? $ENV{HOME}.'/.my.cnf'
              : (-e '/root/.my.cnf')
              ? '/root/.my.cnf'
              : (-e './.my.cnf')
              ? './.my.cnf'
              : 'NOTFOUND';

    die "No valid defaults file found!" if ($defaults eq 'NOTFOUND' && !defined $opts{host});
    
    $dsn = defined $opts{host} && defined $opts{port}
         ? sprintf("DBI:mysql:mysql:host=%s;port=%d;mysql_read_default_file=%s;mysql_read_default_group=mysql;",
                   $opts{host},
                   $opts{port},
                   $defaults)
         : defined $opts{host}
         ? sprintf("DBI:mysql:mysql:host=%s;mysql_read_default_file=%s;mysql_read_default_group=mysql;",
                   $opts{host},
                   $defaults)
         : defined $opts{socket} && -e $opts{socket}
         ? sprintf("DBI:mysql:mysql;mysql_read_default_file=%s;mysql_read_default_group=mysql;mysql_socket=%s;",
                   $defaults,
                   $opts{socket})
         : sprintf("DBI:mysql:mysql;mysql_read_default_file=%s;mysql_read_default_group=mysql;",
                   $defaults);

    $dbh = DBI->connect($dsn, undef, undef, {RaiseError => 1, AutoCommit => 0});
    $dbh->do(sprintf('SET SESSION wait_timeout = %d',
                     $opts{interval} > 3500 ? $opts{interval} + 100 : 3600)) || die "Could not set session wait_timeout";

    return ($dbh);
}