Create a new user in UBuntu 18.04 and enable remote SSH login

create_user.sh

#!/usr/bin/env bash

say() {
 echo "$@" | sed \
         -e "s/\(\(@\(red\|green\|yellow\|blue\|magenta\|cyan\|white\|reset\|b\|u\)\)\+\)[[]\{2\}\(.*\)[]]\{2\}/\1\4@reset/g" \
         -e "s/@red/$(tput setaf 1)/g" \
         -e "s/@green/$(tput setaf 2)/g" \
         -e "s/@yellow/$(tput setaf 3)/g" \
         -e "s/@blue/$(tput setaf 4)/g" \
         -e "s/@magenta/$(tput setaf 5)/g" \
         -e "s/@cyan/$(tput setaf 6)/g" \
         -e "s/@white/$(tput setaf 7)/g" \
         -e "s/@reset/$(tput sgr0)/g" \
         -e "s/@b/$(tput bold)/g" \
         -e "s/@u/$(tput sgr 0 1)/g"
}


create_user () {
    user=$1

    if [ -z "$user" ]
      then
        say @red[["You need to pass a user name to create the new user"]]
        exit 1;
    fi

    say @green[["Creating user '$user'"]]
    adduser $user
    usermod -aG sudo $user
}

install_ssh_key () {
    user=$1
    key=$2

    if [ -z "$user" ]
      then
        say @red[["You need to pass a user name to whom you want to add a SSH key for"]]
        exit 1;
    fi

    if [ -z "$key" ]
      then
        say @red[["You need to pass the public key content"]]
        exit 1;
    fi

    say @green[["Login in as '$user' and creating the 'authorized_keys' file"]]
    su - $user -c \
        "mkdir -p ~/.ssh && \
        chmod 700 ~/.ssh && \
        echo $key >> ~/.ssh/authorized_keys && \
        chmod 600 ~/.ssh/authorized_keys && \
        exit"
}


# read the user name and create user
read -p "Enter the new user name: " usr
echo

create_user $usr


# read SSH key contents and add to authorized_keys
read -s -p "Enter the PUBLIC SSH key to login: " key
echo

install_ssh_key $usr "$key"