Install or update R software on Linux

Follow these instructions to install updates of R software on your Linux distribution :

For Mint 20, install Ubuntu focal version of R.
For Mint 19, install Ubuntu bionic version of R.
For Mint 18, install Ubuntu xenial version of R.
For LMDE 4, install Debian buster version of R.
Follow instructions to install R on Ubuntu.
Follow instructions to install R on Debian.
Follow instructions to upgrade to R 4.0.0 on Debian.