Sorry - I didn't notice the version in the title of the post! :/
OK, version 20.04 - which is code-named "Focal fossa".
From taking a quick look at the ppa here:
Unofficial CDEmu packages
launchpad.net
The ppa has focal builds available of the following packages:
cdemu-client, cdemu-daemon, gcdemu, image-analyzer and libmirage.
Are you sure that add-apt-repository worked properly?
Try running the commands again:
Bash:
sudo add-apt-repository ppa:cdemu/ppa
sudo apt update
Then you should be able to install the packages you want using:
Bash:
sudo apt install cdemu-client cdemu-daemon gcdemu
Or whatever packages you're after!
As far as I can see that should all work.
Unfortunately I'm on Debian, so I'm unable to test the ppa for you. ppa's are more of an Ubuntu thing.
One of the others here might have a *buntu 20.04 installed and may be able to double check it.
But if going through that process again doesn't work - open up /etc/apt/sources.list in a terminal text editor (as root):
e.g.
Bash:
sudo nano /etc/apt/sources.list
I'm a vim user myself, but I've used nano in the above example because it's installed by default on the *buntu's and many ordinary users prefer it... Again - use whatever you prefer!
With the file open in your preferred editor - add the following lines (if they aren't there already!):
Bash:
deb http://ppa.launchpad.net/cdemu/ppa/ubuntu focal main
deb-src http://ppa.launchpad.net/cdemu/ppa/ubuntu focal main
Save the file and exit your editor and then run the commands:
Bash:
sudo apt update
sudo apt install {whatever packages you need}
If the ppa is already in your sources.list and you're still not seeing the packages - I don't really know what to suggest. Because there are definitely builds available for focal.
The only other option I can think of, as a last resort would be to clone their git repo and then build and install from source:
CDEmu code. Contribute to cdemu/cdemu development by creating an account on GitHub.
github.com
But that could be a long and arduous process, especially if you're not used to building and installing software from source. Because you'd need to download and install all of the tools and libraries needed to build the cdemu programs.
Is possible install cdemu for Ubuntu previous version ?
No, that wouldn't be a good idea. A build for a previous version of Ubuntu could rely on older versions of system libraries. That could potentially cause more problems than it solves.
Your best option is to try running through the ppa instructions again. If that doesn't work, manually edit /etc/apt/sources.list and try again.
And if all else fails - cloning from github and building/installing from source is your last resort.