Installing rgl on Ubuntu and Mac: X11 not found

Question

I have seen this question here: Error in loading rgl package with Mac OS X but there is no mentioning about installation error, which is my case. I cannot install rgl<

Answer 1

On Ubuntu, what worked for me was to install the package directly from the command line:

sudo apt-get install r-cran-rgl

(We have a strange setup here, so YMMV)