# Linux commands: who

> Learn how the Linux who command lists the users currently logged in to the system, why you appear multiple times, and what the -aH flags add to the output.

Author: [Flavio Copes](https://flaviocopes.com/about/) | Published: 2020-09-18 | Topics: [CLI](https://flaviocopes.com/tags/cli/) | Canonical: https://flaviocopes.com/linux-command-who/

The `who` command displays the users logged in to the system.

Unless you're using a server multiple people have access to, chances are you will be the only user logged in, multiple times:

![Terminal showing who command output with user flavio logged in multiple times on different ttys terminals with timestamps](https://flaviocopes.com/images/linux-command-who/Screen_Shot_2020-09-03_at_18.03.05.png)

Why multiple times? Because each shell opened will count as an access.

You can see the name of the terminal used, and the time/day the session was started.

The `-aH` flags will tell `who` to display more information, including the idle time and the process ID of the terminal:

![Terminal showing who -aH command output with column headers USER LINE WHEN IDLE PID COMMENT and detailed session information](https://flaviocopes.com/images/linux-command-who/Screen_Shot_2020-09-03_at_18.05.29.png)

The special `who am i` command will list the current terminal session details:

![Terminal showing who am i command output displaying single line with current user flavio on ttys004 terminal](https://flaviocopes.com/images/linux-command-who/Screen_Shot_2020-09-03_at_18.06.35.png)

![Terminal showing who -aH am i command with detailed header columns and current session info including PID for user flavio](https://flaviocopes.com/images/linux-command-who/Screen_Shot_2020-09-03_at_18.07.30.png)

> The `who` command works on Linux, macOS, WSL, and anywhere you have a UNIX environment