How to add new Users to Ubuntu tablet BQ M10?

I have just unboxed my all-new BQ Aquaris M10 Ubuntu Edition and started it for the first time. The device comes with Ubuntu 15.04 pre-installed. While playing around, I was unable to find any setting menu to add new users to the device. One of the main reasons for my decision to wait four years for an Ubuntu powered tablet was to have all users use their own system account.

Update: I have added a Terminal app from the Ubuntu store. I opened a root console and tried

# adduser USERNAME --ingroup phablet

This is what happens:

Adding user `USERNAME' ...
Adding new user `USERNAME' (1002) with group `phablet' ...
useradd: cannot lock /etc/passwd; try again later.
adduser: `/usr/sbin/useradd -d /home/USERNAME -g phablet -s /bin/bash -u 1002 USERNAME' returned error code 1. Exiting.

Error code 1 for useradd command says Can't update password file according to http://linux.die.net/man/8/useradd

So, how to add and edit user profiles on the tablet?

Solution 1:

To add users via the gui :

go to the System Settings (the cog icon) -> User Accounts

If you want to add users via the cli:

sudo adduser USERNAME --ingroup phablet

If you still have problems:

check the permissions of the password file: ls -l /etc/passwd

they should be -rw-r--r-- and belong to root:root

you can fix this with chmod to change permissions and chown to change owners. For info on how to use those commands postfix --help to see thier options.