Not able to find libcudnn8

I am installing a new fresh ubuntu18.04 install.
I have 4 RTX 2080Ti and I want to have an up-to-date Tensorflow install.
Consequently, I am using the GPU Tensorflow install code line proposed from Compatibilité avec les GPU  |  TensorFlow

When I try the following line, ubuntu is not able to locate Cudnn8:
sudo apt install ./libnvinfer7_7.1.3-1+cuda11.0_amd64.deb
sudo apt-get update

Install development and runtime libraries (~4GB)

sudo apt-get install --no-install-recommends

Do you have any advice ?

I thought the correct command to install a .deb is: apt deb package.deb
But might not be a difference, i don’t know for sure.

You could try to locate the package that provides libcudnn8 with: apt-file search libcudnn8

These command lines are coming from Tensorflow website. I am surprised they are not working

@edouard.dekytspotter have you been able to solve this? I have the same issue when I am trying to install Tensorflow following their instructions.