You don’t need to use any GUI applications to show all your users on your system . You can do it via your terminal command-line application. You can list all system generated and human created or normal Linux users via the below commands. Lots of options are available. Just try all commands in your terminal and find the difference. If any other options available please mention in comments.
List all users on Ubuntu:
cat /etc/passwd
getent passwd
less /etc/passwd
more /etc/passwd
Below commands shows only the users name only.
compgen -u
cut -d: -f1 /etc/passwd
awk -F':' '{ print $1}' /etc/passwd
List all Human or Normal users on Ubuntu:
cut -d: -f1,3 /etc/passwd | egrep ':[0-9]{4}$' | cut -d: -f1
awk -F'[/:]' '{if ($3 >= 1000 && $3 != 65534) print $1}' /etc/passwd
Below hack is not a correct method but it will work on most situations.
getent passwd $(ls /home) | grep -o '^[^:]*'
ls /home
