View current logins in Oracle (https://app.pluralsight.com/library/courses/oracle-performance-tuning-developers/table-of-contents)

current_logins.sql

select username, osuser, program, module,
    machine, terminal, process,
    to_char(logon_time, 'YYYY-MM-DD HH24:MI:SS') as logon_time,
    status,
    case status
        when 'ACTIVE' then null
        else last_call_et
    end as idle_time
from v$session
where type = 'USER';