Sql*plus login.sql file

SQLPATH/login.sql

The User Profile is executed after the Site Profile and is intended to allow users to specifically customize their session. The User Profile script is generally named login.sql. SQL*Plus searches for the User Profile in your current directory, and then the directories you specify with the SQLPATH environment variable. SQL*Plus searches this colon-separated list of directories in the order they are listed.
Content of my file

set echo off
set termout off
set feedback off
set serveroutput on size 1000000
set trimspool on
set long 5000
set linesize 120
set pagesize 9999
column plan_plus_exp format a80
column global_name new_value gname
define _editor="C:\Program Files\IDM Computer Solutions\UltraEdit-32\Uedit32.exe"
define sqlplprompt=idle
column sqlplprompt noprint new_value sqlplprompt
-- user@connect_identifier
--select LOWER(user) || '@' || '&_CONNECT_IDENTIFIER' sqlplprompt from dual;
-- user@sqlprompt
--select LOWER(user) || '@' || global_name sqlplprompt from global_name;
-- connect identifier only
define sqlplprompt=&_CONNECT_IDENTIFIER
set sqlprompt '&sqlplprompt.>'
ALTER SESSION SET statistics_level = ALL;
set termout on
set feedback on

--set timing ondefine

Also you can use glogin.sql file, but usually we don’t have access to it

The Site Profile script is generally named glogin.sql. SQL*Plus or the iSQL*Plus Server executes this script whenever a user starts a SQL*Plus or iSQL*Plus session and successfully establishes the Oracle Database connection. The Site Profile enables the DBA to set up SQL*Plus environment defaults for all users of a particular SQL*Plus or iSQL*Plus Application Server installation. Users cannot directly access the Site Profile.The Site Profile script is $ORACLE_HOME/sqlplus/admin/glogin.sql in UNIX, and %ORACLE_HOME%\sqlplus\admin\glogin.sql in Windows.