how to change user in ubuntu terminal code example

Example 1: 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

Example 2: change user linux

sudo su - username

Example 3: change username ubuntu

# -l changes login name
# -d changes home directory
# -m copies over contents from old home directory
usermod -l <newname> -d /home/<newname> -m <oldname>

# NOTE: will not work if you are currently logged on as user
# - workaround by temporarily enabling root account and running above command there
# [sudo passwd root] 
# - after root account has been used to change username lock it using
# [sudo passwd -l root]

Example 4: change ubuntu username

# To manage every aspect of the user database, you use the usermod tool.
# To change username (it is probably best to do this without being logged in):

sudo usermod -l newUsername oldUsername
# This however, doesn't rename the home folder.
# To change home-folder, use

sudo usermod -d /home/newHomeDir -m newUsername

Example 5: switch user ubuntu

$ su - user2