systemd-first-boot-script/scripts/04-create-default-user

#!/bin/bash
# Licence : GPL v3
# Author: Laurent HUBERT
#
# Creates a new user for administrative purposes (in sudo group)
#
cat <<EOF
+---------------------------------------------+
| Creating default user                       |
+---------------------------------------------+
EOF
read -p "Please enter default user name: " the_user

if [ -n "$the_user" ]
then
  echo Creating user $the_user
  # Creates the user but disable the login to set the password later:
  adduser --gecos ,,,, --disabled-login $the_user
  status=$?
else
  # Exit with non zero status
  exit 1
fi

if [ 0 -ne "$status" ]
then
  echo "### Error creating $the_user   ###"
  echo "### Please try again by rebooting your system  ###"
  exit 1
else
  # Adds new user to sudo group
  adduser $the_user sudo
fi

status=1
while [ 0 -ne "$status" ]
do
  passwd $the_user
  status=$?
  if [ 0 -ne "$status" ]
  then
    echo "# Error changing $the_user password   #"
    echo "Please try again"
  else
    echo "> $the_user : created successfully <"
    exit 0
  fi
done

echo "### An error occurred changing $the_user password   ###"
exit $status