I want to sudo apt build-dep r-base under Ubuntu 16.04 (running in Linux on DeX Beta). To this end, I followed this link and put
deb https://cloud.r-project.org/bin/linux/ubuntu xenial-cran35/
deb http://ports.ubuntu.com/ubuntu-ports/ xenial-backports main restricted universe
deb-src http://ports.ubuntu.com/ubuntu-ports/ xenial-backports main restricted universe
into /etc/apt/sources.list, then did
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys E298A3A825C0D65DFD57CBB651716619E084DAB9
and then
sudo apt update
sudo apt build-dep r-base
... but obtain:
Reading package lists... Done
E: Unable to find a source package for r-base
I've done these things before and recently under Ubuntu 19.04 (guess that's not relevant), is the aarch64 architecture a possible problem here? (I could install all sorts of preliminaries to build R from source (Tcl/Tk, GSL, GMP, MPFR...), all no problem). Let me know if you need the output of certain commands.
Note:
Concerning /etc/apt/sources.list: There was already a line deb http://ports.ubuntu.com/ubuntu-ports/ xenial main restricted and I also commented in the same line starting with deb-src instead of deb. This led to exactly the same output. The file also contains the lines deb http://ports.ubuntu.com/ubuntu-ports/ xenial universe.
