who Command: Tutorial & Examples
Display a list of users which are currently logged in
who command is a utility in Linux and other Unix-like operating systems that shows information about users who are currently logged in to the system. When you run the
who command, it displays a list of users along with their login names, the terminal they are using, and the time they logged in.
Here is an example of the output of the
who user1 tty1 2022-12-19 09:15 user2 tty2 2022-12-19 09:17 user3 pts/0 2022-12-19 09:19 (192.168.1.100)
In this example, the
who command shows that three users,
user3, are currently logged in to the system. The
pts fields indicate the terminal that the user is using to access the system. The
tty stands for "teletype" and refers to a physical terminal, while
pts stands for "pseudo terminal slave" and refers to a terminal emulator, such as
gnome-terminal. The time that each user logged in is also shown.
You can use the
-q option with the
who command to show a count of the number of users currently logged in, rather than a list of the users themselves.
who -q # users=3
You can use the
-H option to show a list of the fields that who displays, along with their names. This can be helpful if you want to parse the output of the
who command in a script.
who -H NAME LINE TIME IDLE PID COMMENT user1 tty1 2022-12-19 09:15 1234 user2 tty2 2022-12-19 09:17 1235 user3 pts/0 2022-12-19 09:19 1236 (192.168.1.100)
There are several other options that you can use with the
who command to customize its output. For example, you can use the
-b option to show the time of the last system boot, or the
-u option to show the time that each user was last active on the system. You can see a full list of options by running
who --help or by consulting the
who man page.