This article explains how to view users who are currently logged into a Juniper device that is running Junos.
show system users
user@ex9208-re0> show system users
3:08PM up 8 days, 22:09, 2 users, load averages: 0.48, 0.33, 0.29
USER TTY FROM LOGIN@ IDLE WHAT
user pts/1 10.1.1.100 3:08PM - -cl
user2 pts/0 10.1.1.101 Mon01PM 2days -cl