How to enable AUTOTRACE in oracle

Any session can run the autotrace by SET AUTOTRACE ON at SQL*PLUS But you will get the following error if it is not enabled.

SQL :> set autotrace on;
SP2-0613: Unable to verify PLAN_TABLE format or existence
SP2-0611: Error enabling EXPLAIN report
SP2-0618: Cannot find the Session Identifier. Check PLUSTRACE role is enabled
SP2-0611: Error enabling STATISTICS report

1.Run plustrce.sql through SYS schema if it did not run before as
ON NT :- @$ORACLE_HOME\sqlplus\admin\plustrce.sql
ON UNIX :- @$ORACLE_HOME/sqlplus/admin/plustrce.sql

2.Grant PLUSTRACE to
Also PLAN_TABLE must exist in the USER’s Schema ,if user want to do autotrace with explain plan . For creation of plan_table , UTLXPLAN.sql have to be in user’s schema.

ON NT :- $ORACLE_HOME\rdbms\admin\utlxplan.sql
ON UNIX :-$ORACLE_HOME/rdbms/admin/utlxplan.sql

User can use the AUTOTRACE options ad follows
SET AUTOTRACE OFF - No AUTOTRACE report is generated. This is the default.
SET AUTOTRACE ON EXPLAIN - The AUTOTRACE report shows only the optimizer execution path.
SET AUTOTRACE ON STATISTICS - The AUTOTRACE report shows only the SQL statement execution statistics.
SET AUTOTRACE ON - The AUTOTRACE report includes both the optimizer execution path and the SQL statement execution statistics.
SET AUTOTRACE TRACEONLY - Like SET AUTOTRACE ON, but suppresses the printing of the user's query output, if any.