Install specific R version in Ubuntu

Install R in your preferred version:

sudo bash bionic/install-r.sh <version> <date-for-mran>

Set additional default repositories

export REPO=<your-local-repo> 
sudo bash set-repo.sh <version>

Install R package

sudo bash install-pkg.sh <version> <pkg>

Install all R packages from repo

export REPO=<your-local-repo> 
sudo bash install-repo.sh <version>

Uninstall all R packages from repo

export REPO=<your-local-repo> 
sudo bash uninstall-repo.sh <version>

Example

To install R in version 3.5.1 and 3.5.2 on one system, you can run:

sudo bash bionic/install-r.sh 3.5.1 2018-08-31
sudo bash bionic/install-r.sh 3.5.2 2019-03-10
# set repository
export REPO=<your-local-repo> 
sudo bash set-repo.sh 3.5.1
sudo bash set-repo.sh 3.5.2
# install packages
sudo bash install-pkg.sh 3.5.1 tidyverse
sudo bash install-pkg.sh 3.5.2 tidyverse
# install repositories
sudo bash install-repo.sh 3.5.1
sudo bash install-repo.sh 3.5.2

Now you have a 'base' stack of R packages for all your users installed. The command R is bound to the latest version you installed. A specific version can be launched using:

R -e 'sessionInfo()'
R-3.5.1 -e 'sessionInfo()'
R-3.5.2 -e 'sessionInfo()'

Gotchas

bionic/install-r.sh assumes that the local installation of apt has the source repositories for r-base activated. If this is not the case, e.g. in a fresh installation of a server ubuntu, you may add the following lines to the configuration:

sudo su -c "echo 'deb-src http://de.archive.ubuntu.com/ubuntu/ bionic universe
deb-src http://de.archive.ubuntu.com/ubuntu/ bionic-updates universe' > /etc/apt/sources.list.d/r-sources.list"
sudo apt update

and remove it with

sudo rm /etc/apt/sources.list.d/r-sources.list
sudo apt clean
sudo apt update