Question

I am not sure if this has already been answered here on stack-overflow. I had Emacs-ESS installed on my Unix machine and when ever I start up emacs, particular version of R gets loaded.
I now have some new R packages that I wanted to test before installing into default R environment. Hence I installed newer version of R in a local directory and have my new packages installed there. Now if I want to call this newer R version that I installed in a local directory, from emacs, how exactly should I be doing it? I want to be able to call either the default R version or the locally installed R-version.

Thanks for all your time and help

Answer 1

ESS can start other versions of R, provided that it knows where on your system they are located. Pasted below is the relevant section from the ESS manual:

If you have other versions of R or
S-Plus available on the system, ESS is
also able to start those versions. How
this exactly works depend on which OS
you are using, as described in the
following paragraphs. The general
principle, regardless of OS, is that
ESS searches the paths listed in the
variable exec-path for R binaries. If
ESS cannot find your R binaries, on
Unix you can change the unix
environment variable PATH, as this
variable is used to set exec-path.

R on Unix systems: If you have
“R-1.8.1” on your exec-path, it can be
started using M-x R-1.8.1. By default,
ESS will find versions of R beginning
“R-1” or “R-2”. If your versions of R
are called other names, consider
renaming them with a symbolic link or
change the variable ess-r-versions. To
see which functions have been created
for starting different versions of R,
type M-x R- and then hit [Tab]. These
other versions of R can also be
started from the “ESS->Start
Process->Other” menu.