SHELL

create user ubuntu command line

sudo adduser USERNAME
# choose password
# other fields can be left empty
sudo usermod -aG sudo USERNAME

# change user to check if everything is ok
su - USERNAME
whoami
#  output > USERNAME
sudo whoami
# output > root or an error

# if error switch back to the other account
# and do the following to modify /etc/sudoers

sudo visudo
# find a line like "root ALL=(ALL:ALL) ALL" (or similar)
# add an identical line for USERNAME, like
# "USERNAME ALL=(ALL:ALL) ALL"
Ctrl+O, Ctrl+X  # save and exit
# change user to check if everything is ok

ubuntu create user

useradd is a low level utility for adding users. On Debian,
   administrators should usually use adduser(8) instead.

add new user to in Linux Ubuntu

useradd -d /home/me -s /bin/bash -G sudo me