The cubrid_lob_close function closes the storage file of BLOB/CLOB type returned by cubrid_lob_get().
bool cubrid_lob_close (array $lob_identifier_array)
<?php
$lobs = cubrid_lob_get($con, "SELECT doc_content FROM doc WHERE doc_id=5");
cubrid_lob_export($conn, $lobs[0], "doc_5.txt");
cubrid_lob_close($lobs);
?>