Using SQL*Plus, the Oracle Interface (Cont.)
spool [ file_name|OFF|OUT ]
Stores query results in an operating system file. 
   SQL> spool results.lst 
   SQL> select * from customers; 
   SQL> spool off
   SQL> host cat results.lst

show option
Shows the value of an SQL*Plus system variable, or the current SQL*Plus environment. 
   SQL> show all 
   autocommit OFF
   ...
describe [ object ]
DESCRIBE lists the column definitions of a table. 
   SQL> describe customers; 
   Name                    Null?     Type
   ----------------------- --------  -----------------
   NAME                              VARCHAR2(32)
   SSN                     NOT NULL  CHAR(10)
   NO                                NUMBER(38)
clear option
Resets or erases the current value or setting for the specified option. 
   SQL> clear screen
pause [ text ]
Displays the specified text then waits for the user to press RETURN.

exit
Commits or rolls back all pending changes, logs out of Oracle, terminates SQL*Plus and returns control to the operating system.