I tried to install R 4.1 on a newly set-up Ubuntu 20.04. After some struggle with the repositories and keys, I chose to install from source.
Visited https://www.r-project.org/ to download latest version of R. Ran ./configure multiple times to note the requirement of various libraries which you may note as follows. I am hoping this will save significant amount of time for anyone intending to build from source. Suggestions welcome for speeding up the process or better solution. However my intention is to share entire set of libraries that I had to install on a naked installation of 20.04 on which the very first package I tried to install was R 4.1 (from source).
Directory where you downloaded the tar.gz (e.g. R-4.1.2.tar.gz in my case)
cd Downloads
Untar
tar -xvzf R-4.1.2.tar.gz
Enter directory
cd R-4.1.2
As root
sudo su
Try validating configuration (encountered many errors throughout and following libraries were installed)
./configure
Installed various libraries:
apt-get install build-essential
apt-get install gfortran
apt-get install fort77
apt-get install libreadline-dev
apt-get install xorg-dev
apt-get install liblzma-dev libblas-dev
apt-get install gcc-multilib
apt-get install libbz2-dev
apt-get install libpcre2-dev
apt-get install libcurl4-openssl-dev
apt install default-jdk
make
make install
The above set worked for me and I am hopeful it may be of help.