use Fcntl;
use SDBM_File;
tie (%h, 'SDBM_File', 'data.dbm', O_RDWR|O_CREAT, 0640)
     || die $!;          # This opens the data file
$h(a) = 20;              # This writes the file
while (($k, $v) = %h) {  # Iterates over all keys
    print "$k,$v\n"
}
untie %h;                # Flush and close the dbm file