这里有一个小例子：

sql> create directory tmp as '/tmp/';

Directory created

sql> CREATE OR REPLACE PROCEDURE write_log AS
  2     l_line VARCHAR2(255);
  3     l_done NUMBER;
  4     l_file utl_file.file_type;
  5  BEGIN
  6     l_file := utl_file.fopen('TMP','foo.log','A');
  7     LOOP
  8        EXIT WHEN l_done = 1;
  9        dbms_output.get_line(l_line,l_done);
 10        utl_file.put_line(l_file,l_line);
 11     END LOOP;
 12     utl_file.fflush(l_file);
 13     utl_file.fclose(l_file);
 14  END write_log;
 15  /

Procedure created

sql> BEGIN
  2     dbms_output.enable(100000);
  3     -- write something to DBMS_OUTPUT
  4     dbms_output.put_line('this is a test');
  5     -- write the content of the buffer to a file
  6     write_log;
  7  END;
  8  /

PL/sql procedure successfully completed

sql> host cat /tmp/foo.log

this is a test