How to create oracle users with OS Authentication?

we can use either the  CREATE EXTERNALLY SQL statement or  by creating OS roles and assign these roles to database users to create and authenticate users through OS.

Creating users through the CREATE EXTERNALLY SQL statement:

SQL>  ALTER USER <username> IDENTIFIED EXTERNALLY.

Example:

SQL> conn sys/orcl@to_primary as sysdba
Connected.
SQL> create user solomon identified externally;
 User created.
 SQL>

SQL> grant create session to solomon;
 Grant succeeded.
 SQL