create_user.sh

#! /usr/bin/env bash

# normally first char of prename + surname
users="${@:-jsmith}"

# normally users
group="users"

# normally adm and/or sudo
groups="adm,sudo"

# optional file containing all known SSH pub keys in authorized_keys format
all_auth_keys_file=$(dirname $0)/authkeys

for user in ${users}; do
  auth_keys_file=/home/${user}/.ssh/authorized_keys
  echo "Creating access for user: ${user}"
  useradd -s /bin/bash -m ${user} -g ${group} -G ${groups} -c "manually created on $(date +%Y%m%d-%H%M%S)"
  mkdir -m 0700 /home/${user}/.ssh
  [ -f "${auth_keys_file}" ] || install -b -m 0600 /dev/null ${auth_keys_file}
  if [[ -r ${all_auth_keys_file}  &&  $(grep ${user} ${all_auth_keys_file}) ]]; then
    echo "Found user's SSH key in authorized_keys database ${all_auth_keys_file} file"
    cat ${all_auth_keys_file} >>${auth_keys_file}
  else
    echo "SSH key for user ${user} not found in authorized_keys database ${all_auth_keys_file}, so add key manually"
    echo "Now paste user's SSH pub key here, make sure to end with new line and press CTRL+D to exit"
    echo ${auth_keys_file}
    cat >>${auth_keys_file}
  fi
  sed -i "/.*${user}.*/!d" ${auth_keys_file}
  echo "SSH pub key stored in ${auth_keys_file}"
  chown -R ${user}:${group} $(dirname ${auth_keys_file})
  echo -e "... User '${user}' done\n"
done