Setup ubuntu server on Raspberry Pi 4 without keyboard

The "ssh" file seems to work for me. I just installed the RPi 4 with ubuntu-server 19.10.1. Here are the full instructions for anbody who finds it:

After you have installed ubuntu-server to your SD-card, mount the first partition (usually /dev/mmcblk0p1) on the machine that you installed the SD-card with.

Next, create a file called "ssh" on the filesystem root (it does not have to have any content, as long as the file is there when the pi boots the first time, it will enable ssh).

You then should find the ip address of your pi using either the web-ui on your modem, or by running the following comand from a linux box with nmap installed: nmap -p 22 / (e.g.: nmap -p 22 192.168.1.1/24)

Now you can ssh into the machine with the username "ubuntu" and password "ubuntu". It will then ask you to change the password and disconnect you. That's it, you should have a new password.