R help - Jan 2013 - Setting -sys.setenv()- permanently in Linux using RStudio

> sessionInfo()R version 2.15.2 (2012-10-26)
Platform: i686-pc-linux-gnu (32-bit)

locale:
 [1] LC_CTYPE=en_GB.UTF-8       LC_NUMERIC=C
LC_TIME=en_GB.UTF-8
 [4] LC_COLLATE=en_GB.UTF-8     LC_MONETARY=en_GB.UTF-8
LC_MESSAGES=en_GB.UTF-8
 [7] LC_PAPER=C                 LC_NAME=C
LC_ADDRESS=C
[10] LC_TELEPHONE=C             LC_MEASUREMENT=en_GB.UTF-8
LC_IDENTIFICATION=C

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

loaded via a namespace (and not attached):
[1] tools_2.15.2


Hello.

I'm trying to get -Sys.setenv()- to set the executable paths _permanently_
when I run a TeX file from inside RStudio (0.97.312), but it won't.

Entering
>
Sys.setenv(PATH="/usr/lib/lightdm/lightdm:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/usr/local/texlive/2012/bin/i386-linux")

and then confirming that R picks up the TeX executables correctly by running
> Sys.which("pdflatex")                                        
pdflatex
"/usr/local/texlive/2012/bin/i386-linux/pdflatex"


and then
> Sys.getenv("PATH")[1]
"/usr/lib/lightdm/lightdm:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/usr/local/texlive/2012/bin/i386-linux"

ensures that my TeX file runs successfully on clicking Compile PDF. But
when I then close and reopen RStudio I am greeted with a yellow bar and a
warning symbol with the message:

"No TeX installation detected. Please install TeX before compiling."

meaning that I have to run the code all over again. This is clearly
undesirable! I successfully installed TeXLive 2012 on my Linux system
yesterday and I have tested that all my TeX files run successfully using
TeXworks, which they do (edits included).

In searching the R-help archives, I could only find one post on this issue

http://r.789695.n4.nabble.com/Add-permanently-environment-variable-td3670920.html

which only deals with the issue in Windows. Reading the help from
-??sys.setenv- provides no answers. I also tried setting a path in my
terminal by

$ export
RPATH=$PATH:/usr/lib/lightdm/lightdm:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/usr/local/texlive/2012/bin/i386-linux
$ sudo ~/.bashrc

and then running
> Sys.setenv(PATH="RPATH")

in RStudio, which runs without complaint, but I then get blank output from
-Sys.which("pdflatex")-
> Sys.which("pdflatex")pdflatex
      "" > Sys.getenv("PATH")[1] "RPATH"


so clearly this is incorrect.

There must be a solution to this that I can't see and I've tried
everything
within my knowledge, so can anybody help me on this?

Thanks.

-- 
Clive Nicholas (clivenicholas.posterous.com)

[Please DO NOT mail me personally here, but at
<clivenicholas@hotmail.com>.
Please respond to contributions I make in a list thread here. Thanks!]

"My colleagues in the social sciences talk a great deal about methodology.
I prefer to call it style." -- Freeman J. Dyson

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