Script to setup users and SSH on a Ubuntu Server 19.04 Raspberry Pi 4 SD card image. By default Ubuntu Server does not enable SSH. So to enable this and create a few users, this script was created and adapted from instructions from the referenced website. This script should be used on a host Linux machine, Ubuntu to see the writeable directory o…

simplified_create_headless_ssh_rpi.sh

#!/bin/sh

# based on instructions from
# https://www.berthon.eu/2017/installing-ubuntu-server-on-raspberry-pi-headless/

session=$(date +"%Y%m%d%H%M%S")

array_users=(
 rooot
)

# Bail out if the temp directory wasn't created successfully.
if [ ! -e $TMPDIR ]; then
  >&2 echo "Failed to create temp directory"
  exit 1
fi

# Make sure it gets removed even if the script exits abnormally.
trap "exit 1"           HUP INT PIPE QUIT TERM
trap 'rm -rf "$TMPDIR"' EXIT

#--------------------------------------------------------------------------------------------------
# Bash Utils Section Section

function verify_log4bash () {
 if [[ ! -e ./log4bash.sh ]]; then
   echo "function: verify_log4bash"
   echo "./log4bash.sh not found...fetching remotely"
   wget http://pretty.pleasemarkdarkly.com:8080/jP8Nd/log4bash.sh
 else
   source "./log4bash.sh"
   log_info "function: verify_log4bash"
   log_info "log4bash will be used"
   verify_log4bash_output
 fi
}

function verify_log4bash_output () {
 log "example log outputs"
 log "log output";
 log_info "log_info output";
 log_success "log_success output";
 log_warning "log_warning output";
 log "end example log outputs"
}

# Bash Utils Section Section
#--------------------------------------------------------------------------------------------------

function log_output () {
  log_info "connect usb/sd card to linux pc"
}

function wait_five_seconds () {
  for i in {5..1..1}; do echo -n "$i..." && sleep 1; done
  log_warning "ready to party"
}

function wait_three_seconds () {
  for i in {3..1..1}; do echo -n "$i..." && sleep 1; done
}

function map_drive () {
  [ -e /mnt/rpi ] log_info "/mnt/rpi mounted" | ln -s /media/$(whoami)/writable/ /mnt/rpi
}

function create_ssh () {
  log_info "function: create_ssh user for ubuntu 19.01 sd card"
  [ -e /mnt/rpi ] log_info "found properly mounted drive" | log_error "rpi mount not found"; return;

  userid=1000
  log_info "starting userid: $userid"
  [ -e /mnt/rpi/etc/passwd ] log_info "found mounted /etc/passwd"; log_warning "adding users..."

  log_info "you have five seconds to change your mind"
  wait_five_seconds

  for user in "${array_users[@]}"
  do
    log_warning "creating user: $user, with userid: $userid"
    log_warning "5 seconds to cancel"
    wait_three_seconds
    echo "$(user):x:$(userid):$(userid):<Full Name>:/home/$(user):/bin/bash" | sudo tee -a /mnt/rpi/etc/passwd
    echo "$(user):x:$(userid):" | sudo tee -a /mnt/rpi/etc/group
    echo "$(user):*::$(user)" | sudo tee -a /mnt/rpi/etc/gshadow
    echo "$(user)::0:0:99999:7:::" | sudo tee -a /mnt/rpi/etc/shadow
    echo "$(user) ALL=(ALL) ALL" | sudo tee /mnt/rpi/etc/sudoers.d/20_$(user)_superuser

    log_warning "current user: $(whoami) .ssh/id_rsa.pub keys being added to created users"
    sudo cp -R /mnt/rpi/etc/skel /mnt/rpi/home/$(user)
    sudo chmod 0750 /mnt/rpi/home/$(user)
    sudo mkdir -m 0700 /mnt/rpi/home/$(user)/.ssh
    cat ~/.ssh/id_rsa.pub | sudo tee -a /mnt/rpi/home/$(user)/.ssh/authorized_keys
    sudo chmod 0600 /mnt/rpi/home/$(user)/.ssh/authorized_keys
    sudo chown -R $(userid):$(userid) /mnt/rpi/home/$(user)
    log_info "created user:  $(user)"
    ((userid=userid+1))
  done

}

function enable_systemd_enabling_ssh () {
   log_info "function: enable_systemd_enabling_ssh"

   cd /mnt/rpi/lib/systemd/system
   sudo rm -vf default.target
   sudo ln -s multi-user.target default.target
   cd /mnt/rpi/etc/systemd/system/multi-user.target.wants
   ln -s /lib/systemd/system/ssh.service ssh.service
   log_warning "last command failing is fine"
}

function main () {
  log_info "function: main"
  [ "$(whoami]" == "root" ] log_info "script runs at root, please review the source to be sure" | log_info "must run as root"; sudo
  [ ! -f ~/.ssh/id_rsa.pub ] log_info "couldn't find ssh/id_rsa.pub. see ssh-keygen" | cat ~/.ssh/id_rsa.pub; log_info "found ./ssh/id_rsa...continuing"
  [ -f ./env ] log_info "overriding default values for users"; source ~/.env | \
     log_info "using internal script array_users: "; for user in "${array_users[@]}"; do echo "$user, "; done

  log_warning "creating users from array including account for rooot"
  create_ssh
  enable_systemd_enabling_ssh
}

verify_log4bash
main "[@]"