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

Question

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:

1. 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))
   

2. opening up bash in emacs using M-x term

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

3. 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.

4. 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

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

Answer 1

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")))

Answer 2

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.