ESS R error: searching for program

Question

I have installed emacs on windows 10 working ok so far. Installed R and ESS. Set system and user path to Rterm.exe as read in some forums. Restarted and opened a R file in emacs. Syntax coloring is Ok, emacs entered ESS-R-mode but I cannot evaluate R code.

Using C-c C-n to evaluate the current line / selection, gives me a message:

"Searching for program: No such file or directory, R"

M-x R prompt for starting project directory, but same message is shown.

Double checked system PATH and everything seems ok. Checked emacs variable "getenv" and path is properly set to Rterm.exe folder.

I can open a shell inside emacs and run R prompt with no issue.

any hint?

UPDATE: tried setting (inferior-R-program-name "C:/Users/joe/R/bin/x64/Rterm") and (inferior-ess-r-program "C:/Users/joe/R/bin/x64/Rterm.exe") to .emacs file and now emacs is stuck on blank screen after asking for R starting project directory. The only way to close it is Task Manager - kill process

Answer 1

It's no longer required to use Rterm.exe; you can just use R.exe directly. To configure the program name that emacs/ESS uses, set the variable in your .emacs like this:

(setq inferior-ess-r-program "R")

Alternatively, press C-h v, select the inferior-ess-r-program variable, and use the Customize interface to set and save the setting.

If you don't have the Windows Path set correctly to include the R/bin folder, you can specify the full path in the setting.

(setq inferior-ess-r-program "C:/Program Files/R/R-3.5.3/bin/R.exe")

Answer 2

If (executable-find "R") returns nil, you can add the R location to exec-path through Customize. On my system, C:\Program Files\R\R-4.1.1\bin\x64. This will resolve the issue.

The easiest way to do this is to C-h v exec-path and then click through the "customize" option link. (Note that exec-path is both a variable and a function, and you want the variable.)