R.exe, Rcmd.exe, Rscript.exe and Rterm.exe: what's the difference?

Question

I'm struggling with the different R executables. What is the difference between R.exe (with or without CMD BATCH option), Rcmd.exe, Rscript.exe and Rterm.exe when running command line in a batch file?

And what is the difference between:

R.exe --no-environ --no-save < "c:\temp\R\test.R" > "c:\temp\R\out.txt" 2>&1

and

R.exe CMD BATCH --no-environ --no-save "c:\temp\R\test.R" "c:\temp\R\out.txt"

No difference in the output.

I cannot find anything about Rcmd.exe and Rscript.exe in the 3079 pages R reference manual.

By the way: I am using Windows.

Benge

How about R Introduction - Invoking R from the command line? And two section later - scripting with R. – Ethylene

Yes, I've read that. But no word about Rcmd.exe and just a few lines about Rscript.exe. help(Rscript) gives me some more information – Benge

$R CMD BATCH test.R out.Rout – Ankylosis

Answer 1

Caveat: I work much more on Linux than Windows:

• Rcmd.exe is a historical left-over as back in the day, you could not do R CMD something on Windows but needed the special executable Rcmd.exe something. That is no longer the case, yet it is provided for backwards compatibility.
• Rterm.exe is also a holdover from the days when Rcmd.exe was used. Can be ignored these days.
• R CMD BATCH is a crutch that was needed in the days before littler and Rscript.exe, and similarly lingering from old docs and habits..
• Rscript.exe is your friend for batch scripts; use it.
• For everything else, there's R.exe.

Other than that, as Marek hinted, the reference manual is the wrong one among the six available manuals. Try the Introduction to R and the Installation and Admin manuals both of which have specific appendices for Windows.

Cooley

Thanks. So I can forget Rcmd.exe and R CMD BATCH? – Benge

I just want to run a R script with command line agurments in a Windows (shell) batchfile. As I understand it correctly R.exe is enough for me. – Benge

R Introduction states "Within a terminal window (...) invoking by R.exe or more directly by Rterm.exe". So for everything else Rterm? – Ethylene

Sorry, forgot about Rterm.exe. Also a leftover. – Cooley

Remarkable: When I start R.exe with a R script by using a batchfile I see a R.exe process AND a Rterm.exe process running in the Windows Task Manager – Benge

There is an important difference between R.exe and Rterm.exe - Rterm.exe is compiled with /LARGEADDRESSAWARE and can allocate 4 GB RAM when run under Windows 64 bit, unlike R.exe (we're talking about 32 bit R running under 64 bit Windows). Why would the R people do this only for Rterm.exe and not for R.exe, if Rterm.exe is obsolete? – Erminois

I can't know why they did it. I know sometimes the smaller package is also faster. – Salmanazar

... also an important difference between R and Rscript in that Rscript does not load package:methods ... and that is part of why it is your friend for batch scripts (faster start up time) : #19680962 – Selfwill

And I demonstrated repeatedly that r starts faster than Rscript -- while also loading package methods. – Cooley

The advice given here should be in the R and RStudio documentation. Rscript.exe is your friend for batch scripts; use it. For everything else, there's R.exe. The R and RStudio documentation is not very helpful for Windows users. R and RStudio are still very much written for the Unix / Linux / Mac OSX community. They need to point out up front what are the leftovers in the Windows R and RStudio distros from ancient Unix and DOS days. – Celesta

Thanks for that lovely explanation. Does anyone know what purpose Rgui.exe serves? Calling it from VBA seems to open the R GUI (outside of RStudio), but doesn't run the desired R script. – Cray