Ubuntu 20.10 Server on Raspberry Pi 4
==============================

Author: Momchil Ivanov <momchil@xaxo.eu>
Date  : 2021.04.09

Introduction
------------

This article contains notes on setting up a Ubuntu 20.10 Server on
Raspberry Pi 4.

Setting up WiFi before first boot
---------------------------------

You have the chance to enter the settings for your wifi network prior
to the first boot. You need to edit the file network-config in the
boot partition of your image.

You can add the following:

wifis:
  wlan0:
    dhcp4: true
    optional: true
    access-points:
      my_wifi_ssid:
        password: "changeme"

Here is an example of the full file network-config:

version: 2
ethernets:
  eth0:
    # Rename the built-in ethernet device to "eth0"
    match:
      driver: bcmgenet smsc95xx lan78xx
    set-name: eth0
    dhcp4: true
    optional: true
wifis:
  wlan0:
    dhcp4: true
    optional: true
    access-points:
      my_wifi_ssid:
        password: "changeme"

Setting up WiFi after first boot
--------------------------------

In case you have already booted the Pi without setting up the wifi
settings, you need to edit the file /etc/netplan/50-cloud-init.yaml.
Here is an example of the file contents:

network:
    ethernets:
        eth0:
            dhcp4: true
            match:
                driver: bcmgenet smsc95xx lan78xx
            optional: true
            set-name: eth0
    version: 2
    wifis:
        wlan0:
            access-points:
                my_wifi_ssid:
                    password: changeme
            dhcp4: true
            optional: true

Alternatively, you can also edit the network-config file as described
in section "Setting up WiFi before first boot". You need to execute

# cloud-init clean -r

afterwards, in order to automatically recreate the file
/etc/netplan/50-cloud-init.yaml with the desired settings.

Reading CPU temperature
-----------------------

To read the CPU temperature, you can execute:

$ awk '{print $1/1000}' < /sys/class/thermal/thermal_zone0/temp

Alternatively:

$ vcgencmd measure_temp

Installing vcgencmd
-------------------

The program vcgencmd is used in some examples for the Pi. You can
install it with:

# apt-get install libraspberrypi-bin

Cleaning up the Ubuntu installation
-----------------------------------

First, remove snapd.

Removing snapd
--------------

To remove snap, execute:

# snap list
# snap remove lxd
# snap remove core18
# snap remove snapd
# apt-get autoremove --purge snapd
# rm -rf ~/snap
# rm -rf /snap
# rm -rf /var/lib/snapd
# rm -rf /var/cache/snapd

Disable the automatic installation of snapd:

# apt-mark hold snapd

Removing cloud-config
---------------------

Cloud-config is not needed after the initial setup and can safely be
removed.

It logs to /var/log/cloud-init.log via
/etc/rsyslog.d/21-cloudinit.conf on each boot.

To remove cloud-config, execute:

# touch /etc/cloud/cloud-init.disabled
# reboot
# apt-get autoremove --purge cloud-init -y
# rm -rf /etc/cloud
# rm -rf /var/lib/cloud

Removing Apport
---------------

To remove apport, execute:

# apt-get autoremove --purge apport

Removing plymouth
-----------------

To remove plymouth, execute:

# apt-get autoremove --purge plymouth

Setup sshd
----------

To speed up ssh login, execute:

# echo 'UseDNS no' >> /etc/ssh/sshd_config

Disable motd-news
-----------------

$ touch $HOME/.hushlogin