SQL> conn scott/tiger
set Connected.
          
SQL> 
SQL> 
SQL> set autot on;
SP2-0618: Cannot find the Session Identifier. Check PLUSTRACE role is enabled
SP2-0611: Error enabling STATISTICS report
SQL> conn /as sysdba 
Connected.
SQL> grant plustrace to scott;
grant plustrace to scott
      *
ERROR at line 1:
ORA-01919: role 'PLUSTRACE' does not exist

SQL> select * from v$version;

BANNER
----------------------------------------------------------------
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Prod
PL/SQL Release 10.2.0.1.0 - Production
CORE    10.2.0.1.0      Production
TNS for Linux: Version 10.2.0.1.0 - Production
NLSRTL Version 10.2.0.1.0 - Production

SQL> @?/sqlplus/admin/plustrce.sql
SQL> 
SQL> drop role plustrace;
drop role plustrace
          *
ERROR at line 1:
ORA-01919: role 'PLUSTRACE' does not exist

SQL> create role plustrace;

Role created.

SQL> 
SQL> grant select on v_$sesstat to plustrace;

Grant succeeded.

SQL> grant select on v_$statname to plustrace;

Grant succeeded.

SQL> grant select on v_$mystat to plustrace;

Grant succeeded.

SQL> grant plustrace to dba with admin option;

Grant succeeded.

SQL> 
SQL> set echo off
SQL> show user;
USER is "SYS"
SQL> grant plustrace to scott;

Grant succeeded.

SQL> conn scott/tiger
Connected.
SQL> set autot on
SQL> set autot 
Usage: SET AUTOT[RACE] {OFF | ON | TRACE[ONLY]} [EXP[LAIN]] [STAT[ISTICS]]
SQL> set autot off
SQL>

[oracle@localhost ~]$ ls /opt/oracle/product/10g/sqlplus/admin/plustrce.sql 
/opt/oracle/product/10g/sqlplus/admin/plustrce.sql
[oracle@localhost ~]$ cat /opt/oracle/product/10g/sqlplus/admin/plustrce.sql 
--
-- Copyright (c) Oracle Corporation 1995, 2002. All Rights Reserved.
--
-- NAME
--   plustrce.sql
--
-- DESCRIPTION
--   Creates a role with access to Dynamic Performance Tables
--   for the SQL*Plus SET AUTOTRACE ... STATISTICS command.
--   After this script has been run, each user requiring access to
--   the AUTOTRACE feature should be granted the PLUSTRACE role by
--   the DBA.
--
-- USAGE
--   sqlplus "/ as sysdba" @plustrce
--
--   Catalog.sql must have been run before this file is run.
--   This file must be run while connected to a DBA schema.

set echo on

drop role plustrace;
create role plustrace;

grant select on v_$sesstat to plustrace;
grant select on v_$statname to plustrace;
grant select on v_$mystat to plustrace;
grant plustrace to dba with admin option;

set echo off
[oracle@localhost ~]$