The Linux Newbie Guide

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Fundamentals

wwho - Display Logged-In Users

The who command is used to display information about users who are currently logged into the system.

The syntax of the who command is as follows:
who [OPTIONS] .

Here are some commonly used options with the who command:

-H: Show the hostname in the output, indicating which host each user is connected to.
-m: Display the terminal name (TTY) associated with each login.
-n: Display only the usernames of logged-in users.
-q: Display only login times and the number of users currently logged in.
-s: Display only the terminal names (TTY) of logged-in users.

Example:

$ who ←Display a list of currently logged-in users
root     tty1         2016-11-19 16:07
lee      tty2         2016-11-19 16:37
kao      tty4         2016-11-19 16:40
chen     tty4         2016-11-19 17:11

The who command is helpful for checking who is currently using the system and on which terminal they are logged in. You can also use it to see when users logged in.

For more options and examples, you can refer to the provided link.