l --marc l's questions

How to setup of Raspberry Pi 3 B+ onboard WiFi for Ubuntu Server 18.04? In particular, with netplan?

Existing answers, such as "How to use onboard wifi on Raspberry Pi 3 with Ubuntu Server 16.04?", no longer seem to apply since /etc/network/interfaces states that netplan has replaced ifupdown.

# ifupdown has been replaced by netplan(5) on this system.  See
# /etc/netplan for current configuration.

This is a clean install of the Ubuntu Server image for Raspberry Pi 3.

##### release ###########################
Distributor ID: Ubuntu
Description:    Ubuntu 18.04.2 LTS
Release:    18.04
Codename:   bionic

##### kernel ############################
Linux 4.15.0-1034-raspi2 #36-Ubuntu SMP PREEMPT Fri Apr 5 06:21:41 UTC 2019 aarch64 aarch64 aarch64 GNU/Linux

According to Ubuntu Wiki RaspberryPI the needed packages should already be in place.

Since 18.04.2 the linux-firmware and linux-firmware-raspi2 packages now contain the necessary files for the built-in WiFi on the Pi 3B and 3B+.

sudo lshw -C network

*-network:0 DISABLED      
   description: Wireless interface
   physical id: 2
   logical name: wlan0
   serial: b8:27:eb:69:f2:3b
   capabilities: ethernet physical wireless
   configuration: broadcast=yes driver=brcmfmac driverversion=7.45.18 firmware=01-6a2c8ad4 multicast=yes wireless=IEEE 802.11
*-network:1
   description: Ethernet interface
   physical id: 3
   logical name: eth0
   serial: b8:27:eb:3c:a7:6e
   size: 1Gbit/s
   capacity: 1Gbit/s
   capabilities: ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation
   configuration: autonegotiation=on broadcast=yes driver=lan78xx driverversion=1.0.6 duplex=full ip=172.16.76.7 link=yes multicast=yes port=MII speed=1Gbit/s

Netplan.io provides some general Netplan configuration examples.

To configure netplan, save configuration files under /etc/netplan/ with a .yaml extension (e.g. /etc/netplan/config.yaml), then run sudo netplan apply.

... yet, no guideance specific to a RaspberryPi. ...in particular, with respect to the existing /etc/netplan/50-cloud-init.yaml file on the RaspberryPi Ubuntu Server install.

##### Netplan config ####################

[/etc/netplan/50-cloud-init.yaml]

# This file is generated from information provided by
# the datasource.  Changes to it will not persist across an instance.
# To disable cloud-init's network configuration capabilities, write a file
# /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
# network: {config: disabled}

network:
    version: 2
    ethernets:
        eth0:
            dhcp4: true
            match:
                macaddress: <MAC 'eth0' [IF1]>
            set-name: eth0

So, given the use of netplan and default generated .yaml file. How should one add a WiFi network SSID and password? And leave the existing wired ethernet in place?

Given: a sudo dd if=/dev/sda of=/dev/sdb duplicate drive of the main boot drive.

How does one safely, reliably :

1. mount a dd duplicate drive as a second drive?
2. setup the dd duplicate drive as alternate boot drive?
3. safe practice to restore from a dd duplicate drive?

My notes so far on for Ubuntu 12.04 are as follows:

• Mount. The Ubuntu Utility Mount Volume gives the error Error mounting: mount exited with exit code 1: helper failed with: mount: according to mtab, /dev/sdb1 is already mounted on / mount failed. Is there a safe way to just mount a duplicate boot volume as a second drive?

• Boot. Function key to select the start up disk from the BIOS/GRUB appears to be the way to go. What does it mean if a blank screen is seen after the disk is selected far what seems to be a long time?

• Restore. If the duplicate is used as the /dev/sda boot drive is sudo dd if=/dev/sda of=/dev/sdb OK as a restore procedure? Or, is it safer use some third minimal boot (e.g. USB) drive for sudo dd if=/dev/duplicate of=/dev/toberestored? or something else?

Background Context: There is an Ubuntu 12.04 embedded system that I would like to migrate forward with a clean (not-upgrade) install of Ubuntu 14.04. This is a single board system with and fixed main SSD drive.

Current thinking is to create the following:

1. File Migration Disk. A mountable drive with the 12.04 files which can be seen by the 14.04 system. (alternately possible with rync)

2. Regression Test Dual-Boot Configuration Disks. A dual boot drive configuration with an external 12.04 drive or fixed internal SSD (with a clean 14.04 install) can be use to boot the system. (can dd be used here?)

3. Baseline Backup Disk. A full image, non-incremental, as-is, if-needed revert to 12.04 recovery drive. (completely separate drive from 1 & 2)

Where could and how would dd if=/dev/sda of=/dev/sdb drive process fit into the above migration scenario?