These are the instructions to setup a custom Ubuntu 18.04 Bionic on Raspberry Pi 4 B.
Obtain Ubuntu 18.04 ARM Image
To install the long term supported (LTS) Ubuntu 18.04 on the Raspberry Pi 4 B James A. Chambers provides a blog post where he created a custom image. His unofficial releases can be found in his github repository.
Download the latest release of the image and flash it to an empty sd card. To do this follow the instructions on the Raspberry Pi documentation or balenaEtcher. Another way is to use the Raspberry Pi Imager explained here.
If you are not in the US it is possible that you encounter connection problems when connected to a 5Ghz Wifi network. If you are in a different country than the US you need to update your regulatory country. 5Ghz needs this to know the right bands to use.
After flashing the image to the sd card insert it to the Pi, hook it up to a monitor via HDMI and power it up.
Once logged in (default password is
ubuntu which needs to be changed after the first login) update Ubuntu:
sudo apt update sudo apt upgrade
Reboot and follow the next steps to install ROS Melodic.
Note that I’ve provided a bash script for the next steps. You can clone the repository: https://github.com/fjp/diffbot.git and run ubuntu-setup.bash