Systemd keeps track of all users who are logged into the system (e.g. on a virtual console or remotely via SSH). The command loginctl allows querying and manipulating user sessions. For instance, to list all user sessions: $ loginctl SESSION UID USER SEAT c1 500 eelco seat0 c3 0 root seat0 c4 500 alice This shows that two users are logged in locally, while another is logged in remotely. (“Seats” are essentially the combinations of displays and input devices attached to the system; usually, there is only one seat.) To get information about a session: $ loginctl session-status c3 c3 - root (0) Since: Tue, 2013-01-08 01:17:56 CET; 4min 42s ago Leader: 2536 (login) Seat: seat0; vc3 TTY: /dev/tty3 Service: login; type tty; class user State: online CGroup: name=systemd:/user/root/c3 ├─ 2536 /nix/store/10mn4xip9n7y9bxqwnsx7xwx2v2g34xn-shadow-4.1.5.1/bin/login -- ├─10339 -bash └─10355 w3m nixos.org This shows that the user is logged in on virtual console 3. It also lists the processes belonging to this session. Since systemd keeps track of this, you can terminate a session in a way that ensures that all the session’s processes are gone: $ loginctl terminate-session c3