How to access a bash environment variable from within R in emacs-ess

In my .bashrc, I have the line:

export SETTINGS=/home/user/settings.xml

If I load R in bash, I can access this variable using the Sys.getenv function:

Sys.getenv("SETTINGS")
"/home/user/settings.xml"

If I open up R in Emacs (M-x R), SETTINGS is empty:

Sys.getenv("SETTINGS")
""

What I have tried:

adding the following to .emacs, based on How do I make Emacs recognize bash environment variables for compilation?

;; get environment vars from .bashrc
(let ((path (shell-command-to-string ". ~/.bashrc; echo -n $SETTINGS")))
  (setenv "SETTINGS" path))

opening up bash in emacs using M-x term

echo $SETTINGS         # works
R
Sys.getenv("SETTINGS") #works

If I open emacs from the terminal, the SETTINGS variable is available as expected. Opening emacs from the Applications menu (with either the command /usr/bin/emacs23 %F or emacs) does not work.

comparing output from session("env") when loading R in bash vs emacs, but nothing stands out other than (bash = <, emacs = >):

> INSIDE_EMACS=23.3.1,comint
6d5
< SETTINGS=/home/user/settings.xml
9c8
< SHLVL=1
> SHLVL=0
14a14
> PAGER=cat
16d15
< PAGER=/usr/bin/pager
19d17
< COLORTERM=gnome-terminal
25c23
< WINDOWID=14680069
> DESKTOP_AUTOSTART_ID=1020ce948b944a88113395253627645060000001863000
< TERM=xterm
> TERM=dumb

Can I either

access SETTINGS from within R in emacs-ess
export SETTINGS somewhere that I can access it?

I don't know about R and self-defined environment variables, but I set the PATH variable in emacs to the same value as in my bashrc. I modified my code to your problem, give it a shot and let me know if it works.

;; set env variable in Emacs
(getenv "SETTINGS")
(setenv "SETTINGS" "/home/user/settings.xml")

Original code (for PATH) is:

;; Emacs has its own path variable
(getenv "PATH")
 (setenv "PATH"
(concat
 "/usr/local/texlive/2011/bin/x86_64-linux" ":"
(getenv "PATH")))

the .bashrc might not be read when the xsession is started. Try adding

export SETTINGS=/home/user/settings.xml

in the .xsessionrc or the .gnomerc (if you are using gnome). Those file are loaded at startup for the X session.

If you start you an R session inside emacs, then the R session will have the same environment variables as emacs. So you should first make sure that you start emacs in such a way that its environment contains your SETTINGS variable. That way, your R session, which you start inside emacs, will have SETTINGS also in its environment. How exactly to achieve this depends on your system.

Jason Morgan

You can put