Update for UbuntuMATE 16.04.6 broke the GUI

[Paul Smith]

On Sun, 2019-08-25 at 22:03 +0800, Bret Busby wrote:
> On both of the two broken systems; 16.04.6 and 18.04.3,
> sudo adduser
> returns
> 
> "
> adduser: Only one or two names allowed.
> "
> 
> then, it returns to the prompt.

adduser, like virtual all POSIX CLI commands, is not interactive: it's
not going to ask you questions.  Instead you have to provide all the
information it needs on the command line.

You can use "man adduser", or Google, to figure out what arguments to
give to the "adduser" command.

However, simpler by far is to use the graphical system configuration
tool to add users.

On Ubuntu, you can bring up Settings, go to the Details tab, and select
Users.  You need to Unlock (button at the top) to get admin privileges
before you can add new users.

> Both (and, all of my Ubuntu) systems are UbuntuMATE.

For administration questions on UbuntuMATE you should be asking on
forums or mailing lists specifically for UbuntuMATE.  The entire reason
for the existence of UbuntuMATE is to provide a different desktop
environment than vanilla Ubuntu, so while most of the applications you
run will work the same, almost all the desktop administration tools
will work differently... and we can't help you with that here.