Setting up SQL*Plus Environment

When I connect to multiple databases in multiple machines, I need to know who I am and where I am connected to prevent any kind of accidental damage.

I took the following "login.sql" script from Tom Kyte's book (Expert Oracle) and modified according to my need-

#login.sql
define _editor=vi
set serverout on size 1000000
set trimspool on
set long 5000
set timing on
set linesize 200
set pagesize 1000
column plan_plus_exp format a80
column global_name new_value gname
set termout off

select lower(user) || '@' || UPPER(SUBSTR(global_name, 1, INSTR(global_name,'.')-1)) global_name from global_name;
set sqlprompt &gname>
set termout on

When I login (connect) to database, it gives me the user and machine information like -
prod7@TERMINUS>

Cool!