To use R on the CLA Linux compute servers, you will first need to load the associated module.
user@c1:~$ module avail R/
--------------------- Languages and Compilers ----------------------
R/mro/3.5.1 R/3.1.2 R/3.4.1 R/3.6.1 (D)
R/2.15.3 R/3.2.3 R/3.5.1 R/4.0.2
user@c1:~$ module load R/3.5.1
If you want to use Rstudio, you will want to connect via NoMachine to lts.cla.umn.edu. From there, you will want to connect to one of the CLA compute servers, submit a job (if you connected to compute.cla.umn.edu), and then load the rstudio module:
user@c1:~$ module avail rstudio
------------------------- Applications -------------------------------
Rstudio/0.98.1087 Rstudio/1.1.456 (D) rstudio/1.0.44 rstudio/1.2.5033
Rstudio/1.0.44 Rstudio/1.2.5033 rstudio/1.0.153
Rstudio/1.0.153 rstudio/0.98.1087 rstudio/1.1.456 (D)
user@c1:~$ module load rstudio/1.1.456
R 3.4.1: loaded
RStudio 1.1.456: loaded
user@c1:~$ rstudio
As you can see from the output above, the Rstudio module also loads an R module, in this case, R 3.4.1. If you want to use a different version of R, just unload the R module and load the one for the version that you want to use.
user@c1:~$ module unload R/3.4.1
R 3.4.1: unloaded
user@c1:~$ module load R/3.5.1
R 3.5.1: loaded