How can I find out who is logged on my UNIX / Linux system?

To find out who is logged on to a Unix or Linux system, you can use the "who" command. This command will show a list of all users who are currently logged in to the system, along with the terminal they are using and the date and time of their login.

To use the "who" command, open a terminal and type the following command:

who

This will show a list of all users who are currently logged in to the system, along with the terminal they are using and the date and time of their login. The output will look something like this:

user1 tty1         2021-01-01 12:34
user2 pts/0        2021-01-01 12:35
user3 pts/1        2021-01-01 12:36

In this example, three users are logged in to the system: "user1" is using terminal "tty1", "user2" is using terminal "pts/0", and "user3" is using terminal "pts/1". The date and time of their login is also shown.

You can use the "who" command to quickly see which users are currently logged in to the system. You can also use other commands such as "w" or "last" to show more detailed information about logged-in users.