Common sqlplus commands

ACCEPT - Get input from the user 
DEFINE - Declare a variable (short: DEF) 
DESCRIBE - Lists the attributes of tables and other objects (short: DESC) 
EDIT - Places you in an editor so you can edit a SQL command (short: ED) 
EXIT or QUIT - Disconnect from the database and terminate SQL*Plus 
GET - Retrieves a SQL file and places it into the SQL buffer 
HOST - Issue an operating system command (short: !) 
LIST - Displays the last command executed/ command in the SQL buffer (short: L) 
PROMPT - Display a text string on the screen. Eg prompt Hello World!!! 
RUN - List and Run the command stored in the SQL buffer (short: /) 
SAVE - Saves command in the SQL buffer to a file. Eg "save x" will create a script file called x.sql 
SET - Modify the SQL*Plus environment eg. SET PAGESIZE 23 
SHOW - Show environment settings (short: SHO). Eg SHOW ALL, SHO PAGESIZE etc. 
SPOOL - Send output to a file. Eg "spool x" will save STDOUT to a file called x.lst 
START - Run a SQL script file (short: @)

source :

http://www.orafaq.com/wiki/SQL*Plus_FAQ