Questions[who](ubuntu)

I opened 4 terminals but when check them with who or w

me@alpha:~$ w
 17:28:19 up  3:09,  1 user,  load average: 0.51, 0.35, 0.34
USER     TTY      FROM             LOGIN@   IDLE   JCPU   PCPU WHAT
me :0       :0               14:20   ?xdm?   3:27   0.01s /usr/lib/gdm3/gdm-x-session --run-script env GNOME_SHELL_SESS
me@alpha:~$ who
me   :0           2019-01-16 14:20 (:0)

It display only one termianl called ':0'

if on macos it will display

me at mbp in ~
$ who
me  console      2019-01-04 08:57
me  ttys000      2019-01-04 08:57
me  ttys001      2019-01-04 08:57

How could display all the terminal ?

What I want is to find the name of the user that runs bash script, when this script is executed by sudo. The only possible way, that I know, is to parse the output of who -m (who am i) in this way:

user@UbuntuServer:~$ cat who.sh 
#!/bin/sh
whoami
echo $USER
who -m | awk '{print $1}'

user@UbuntuServer:~$ sudo ./who.sh 
root
root
user

The problem is: In Ubuntu Desktop 16.04.4 who -m (resp. who am i) do nothing. Why?

Another question is why the Ubuntu's online manual page for who is different from man who executed either on Ubuntu Desktop or Server?

But these questions are not so important according to my goals. And as it is mentioned in the title, the main question is: How do I find which user executes the script when is used sudo?

Practically, the original title - How do I find 'who am I' on Ubuntu Desktop? - is the same but wrongly asked question.

i want to get info via ssh-session, which user is currently using the machine. i get the users which are logged in with "w" or "who" but how can i see which one has currently the desktop open to send him a message using yad?

edit: i found a dirty code.. but works for now:

#!/bin/bash
tty=$(cat /sys/class/tty/tty0/active)
active_user=$(w | grep $tty | awk '{print $1;}')

#to get the display also:
disp=$(who | awk -v term="$tty" '/\(:/ $0 ~ term { gsub(/\(|\)/, "", $0); print $5 }')