Install multiple Ubuntu instances in WSL2

 Yes, there are probably many post about this, such as https://cloudbytes.dev/snippets/how-to-install-multiple-instances-of-ubuntu-in-wsl2 and https://stackoverflow.com/questions/51584765/how-do-you-install-multiple-separate-instances-of-ubuntu-in-wsl. Still want to make this post about a special case not covered anywhere else.

Run wsl -l can show all installed distribution.

If want to remove one of the distribution, run: wsl --unregister <DistributionName>

Recently I'm playing with ROS Kinetic. Unfortunately, as mentioned http://wiki.ros.org/kinetic/Installation/Ubuntu, only old Wily (15.10) and Xenial (16.04 LTS) are supported. It's possible to get it setup with VirtualBox or VMware VM, but I'd like to go with WSL2 on Windows 11, as mentioned in my the other post, it is possible to enable Ubuntu GUI with the Windows 11 build 22000+. One problem here is the Xenial Ubuntu is no longer available from Microsoft Store, so would need to use WSL2 very useful 'import' feature. For this, would need a tar.gz file of the Ubuntu distribution, the ISO image file doesn't work with WSL import. Another problem now, seems there is no tar for the Xenial Desktop image, but the base image is available such as the amd64 one as ubuntu-base-16.04.6-base-amd64.tar.gz, and it is pretty small, just 41MB. Using command like this to import it:

wsl --import xenial c:\Users\%USERNAME%\wsl_xenial .\Downloads\ubuntu-base-16.04.6-base-amd64.tar.gz 

(Note: for imported distro, if run wsl --unregister, it will delete distro file). There is no Ubuntu desktop and only user root is created. To add new user, run following command with the root account to add the user and add it to sudo group:

adduser newuser

usermod -aG sudo newuser

Try this to verify the user group and switch to it:

groups newuser

su - newuser 

Type 'exit' to switch back to root, and run 'apt update' and 'apt install sudo', so later the new user can do apt install with sudo command. This is the minimum for installing other package as new user. 

To get the desktop environment, run: 'sudo apt install ubuntu-desktop', which installs most common packages. On WSL/Windows OS side, need to follow https://learn.microsoft.com/en-us/windows/wsl/tutorials/gui-apps, installing the AMD/nVidia/Intel's Virtual GPU (vGPU) driver first, then run: 'wsl --update' and 'wsl --shutdown' for a clean restart. May install gedit and run it to verify the GUI. Per my testing, with Ubuntu 20.04 LTS the GUI works fine. However, doesn't work for Ubuntu 16.04 Xenial, seeing segment fault and probably core dump. Tried Diagnosing "cannot open display" type issues with WSLg but not much luck. So leave it aside for now.