[R-sig-Debian] Local repo for ubuntu including R

[Göran Broström]

Background:

We have a computer lab with two ubuntu 18.04 machines (and lots of 
windows computers) and I am searching for a convenient way to keep the 
machines up-to-date regarding R in the first place, but also ubuntu 
itself. The problem is that the lab is isolated from the internet.

Some versions of ubuntu ago I had success with apt-mirror and apt-get 
for the OS, but now I cannot get it to work. In my search for help on 
the internet I have come to the conclusion that there is something wrong 
with apt-mirror nowadays.

Question:

What is the best and simplest way to keep the ubuntu machines up-to-date 
regarding OS and R with the apt/apt-get approach?  Alternatives to 
apt-mirror?

Thanks, Göran