my $CACHE = IO::File->new;
   $CACHE->open( $dateiname, O_RDWR|O_BINARY|O_TRUNC ) or die $!;
   # ggf. LOCK_EX

   # Schreiben
   $CACHE->print( $binary );

   # Lesen
   read( $CACHE, my $binary, -s $CACHE);