bzwrite() writes a string into the given bzip2 file stream.
The file pointer. It must be valid and must point to a file successfully opened by bzopen().
The written data.
If supplied, writing will stop after length (uncompressed) bytes have been written or the end of data is reached, whichever comes first.
$str = "uncompressed data";
$bz = bzopen("/tmp/foo.bz2", "w");
bzwrite($bz, $str, strlen($str));