I would like to get Unix group Name mapped to Sentry role in postgreSQL
Sentry permissions can be configured through GRANT and REVOKE statements issued either interactively via Hue or programmatically through the HiveServer2 SQL command line interface, Beeline (documentation available here).
The GRANT ROLE statement can be used to grant roles to groups. Only Sentry admin users can grant roles to a group.
Execute below hive query as sentry admin.