Add user to the ubuntu lightdm drop-down login menu
When you create a new user with useradd on the command-line then it will generally not
show up in the drop-down menu of the ubuntu lightdm login screen. The things
to check are:
Newer linux distributions assume that real users (not machine accounts) start with
a numeric user ID of 1000 or higher. In the past this used to be 500. So if you have been
using linux for more than a decade then check /etc/lightdm/users.conf for
the parameter minimum-uid and set it to 500:
[UserList]
minimum-uid=500
The useradd command-line creates all the necessary files but it will classify the user
as a system account (machine user). Machine users don't show up in the drop-down menu. Check
the files under /var/lib/AccountsService/users and set the parameter SystemAccount=false.
lightdm login screen with drop-down list for user names
