Linux Mint 19 Terminal refuses to add repository despite giving correct source for R3.5 installation files

Question

I have to install the latest version of R on my Linux Mint 19 computer in order to run some bioinformatics tools (Biostrings). I then followed this website for the tutorial (I suppose things are not very different with Mint or Ubuntu after all). However, after I typed in the third command line into the Terminal, which is

sudo add-apt-repository 'deb https://cloud.r-project.org/bin/linux/ubuntu bionic-cran35/'

it replied

Malformed input, repository not added.

Now I understood that there is a typo in the command on the website, and I myself corrected it to

sudo add-apt-repository 'deb https://cloud.r-project.org/bin/linux/ubuntu/bionic-cran35/'

However, the problem still exists.

Could anyone help me with this issue?

Answer 1

sudo nano /etc/apt/sources.list.d/additional-repositories.list

then add the following line

deb [arch=amd64] https://download.docker.com/linux/ubuntu bionic stable

then,

sudo apt update