clear screen:

SQL> clear scr

To make you screen bigger:

SQL> show pagesize
pagesize 14
SQL> show linesize
linesize 80

SQL> set pagesize 25

FEEDBACK ENVIRONMENT:

SQL> set feedback on
SQL> show feedback
FEEDBACK ON for 1 or more rows

FEEDBACK example:

my name is Ford, I started work on 03-DEC-81
my name is Miller, I started work on 23-JAN-82

14 rows selected.

SQL> set feedback off
SQL> show feedback
feedback OFF

SET TIME TO APPAR ON YOUR COMMAND LINE: 

 SQL> set time on
11:45:27 SQL> run mynameis

11:45:38 SQL> set time off
SQL>
SQL>