SQL & PL/SQL

Hi,

Not sure if this is correct forum, but let me try please - how do I supress prompt in sqlplus from being written to a file when spooling, for example, in case

spool ....

select username from dba_users where rownum < &num;

spool off;

When executing the script in sqlplus i am getting this text in the output spool file:

Enter value for num: 8

What is sqlplus setting which will prevent this text to be written into spool?

Thanks,

Anatoliy