How to set R environment in /etc/profile? - r

Question

my os is debian6,there is a libR.pc after i compile to install R
root#debian:/home/tiger# cat /home/tiger/R-2.15.1/lib/pkgconfig/libR.pc
rhome=/home/tiger/R-2.15.1/lib/R
rlibdir=${rhome}/lib
rincludedir=/home/tiger/R-2.15.1/lib/R/include
Name: libR
Description: R as a library
Version: 2.15.1
Libs: -L${rlibdir} -lR
Cflags: -I${rincludedir} -I${rincludedir}
Libs.private:
when set R environment in /etc/profile:
R_HOME= /home/tiger/R-2.15.1
or
R_HOME= /home/tiger/R-2.15.1/lib/R
which line will i choose to write in /etc/profile?

Answer 1

On a Debian (or derivative such as Ubuntu system) you have /etc/R/ to set variable which R uses:
edd#max:~$ ls -l /etc/R/
total 28
-rw-r--r-- 1 root root 602 Jun 17 20:29 ldpaths
-rw-r--r-- 1 root root 5461 Jun 17 20:29 Makeconf
-rw-r--r-- 1 root root 1868 Mar 31 13:50 Renviron
-rw-r--r-- 1 root root 608 Sep 25 2009 Renviron.site
-rw-r--r-- 1 root root 1159 Mar 31 08:03 repositories
-rw-r--r-- 1 root root 792 Oct 28 2009 Rprofile.site
edd#max:~$
and the files in R_HOME/etc/ should be softlinks --- at least if you use the prebuilt binaries. If you build you own binaries, it's your problem.
The file you quote is installed as /usr/lib/pkgconfig/libR.pc on a Debian / Ubuntu system. Setting R_HOME is not needed as R finds its own values (see #flodel's answer).

Answer 2

On my system:
cat $R_HOME
gives nothing, but inside an R session, I get:
> Sys.getenv("R_HOME")
[1] "/usr/lib/R"
This should tell you two things:
that R_HOME is set at R's startup, so unless you know exactly what you are doing, maybe you don't need to set it up in your /etc/profile.
you can use Sys.getenv to find out the exact path to your R_HOME.