If you want to find out who’s currently logged in on the system (and what time they logged in), use the who command:
% who root console Sep 26 17:01 lmui ttyp0 Sep 26 17:47 (harry.ora.com:0.) eap ttyp2 Sep 23 13:54 (nugget.west.ora.) jhm ttyp3 Sep 24 06:00 (fudge.rtr.com) mam ttyp4 Sep 27 07:11 (ncd12.ora.com:0.) ...
You may want to sort your output
The order that who reports information isn’t very meaningful to most of us. Sometimes you may be more interested in seeing who’s logged in, in alphabetical order. To do that, use the sort command.
% who | sort andyo ttyr0 ... bobbi ttys7 ... bobbi ttys8 ... bonnie ttyu3 ... bradley ttyq8 ... ...
For each user, the who command reports what terminal device they’re logged in on, when they logged in, and where they logged in from.