Does anybody use utl_file package with success?

Hello,
I've tried to use the package utl_file
delivered with version 7.3.2.1 on HP-UX 10.x. But I get always the error invalid_path as an exception from utl_file.fopen

SQL> exec create_file('/tmp','f.lis')
invalid_path
PL/SQL procedure successfully completed.

Here is my source code (derived from an example of Steven Feuerstein):

create or replace procedure create_file

        (loc_in in varchar2, file_in in varchar2) is

        file_handle utl_file.file_type;
begin

        file_handle := utl_file.fopen (loc_in, file_in, 'w');

• write something into file

        utl_file.fclose (file_handle);

exception

when utl_file.invalid_path
then dbms_output.put_line('invalid_path');

when utl_file.invalid_mode
then dbms_output.put_line('invalid_mode');

when utl_file.invalid_filehandle
then dbms_output.put_line('invalid_filehandle');

when utl_file.invalid_operation
then dbms_output.put_line('invalid_operation');

when utl_file.write_error
then dbms_output.put_line('write_error');

when utl_file.read_error
then dbms_output.put_line('read_error');

when utl_file.internal_error
then dbms_output.put_line('internal_error'); end;
/
show errors

In the PL/SQL documentation I found the following:

PL/SQL file I/O is available on both the client and server sides. However, on the server side, file access is restricted to those directories explicitly listed in the accessible directories list, which is stored in the Oracle initialization file.

What does it mean? How can I distiguish between client and server ? What does the second sentence mean? I don't know any parameter in the init.ora concerning accessible directories list.

May be there is somebody who can give me an answer to my questions ?

Regards Ekkehard

--
Ekkehard Schulz, Alcatel SEL AG Berlin, Department KB/EF3
Colditzstrasse 34-36, D 12099 Berlin, Germany           
Phone: +49-30-7002-3469  Fax: +49-30-7002-3667
Email: ekkehard.schulz_at_bln.sel.alcatel.de