[R] R doesn't recognize R_HOME value

[peter dalgaard]

On Jul 25, 2012, at 07:58 , Prof Brian Ripley wrote:

> On 24/07/2012 21:57, Kirk Fleming wrote:
>> ???
>> 
>> Windows 7 is where I'm seeing the problem.
>> 
>> The root problem: while I have R_HOME legitimately specified within Windows
>> 7, and issuing 'set R_HOME' from the command line returns exactly the path
>> I've specified, doing a Sys.getenv('R_HOME') from R returns a completely
>> different path.
>> 
>> I ask, "What would cause a Sys.getenv() call to return a different value
>> than the OS does?"
> 
> A different process and hence a different environment ... this is why they are called 'environment variables' and are specific to a process.
> 
> 'The command line' is actually a shell process, not the OS itself. Setting environment variables in a shell affects only that shell and those which inherit from it.
> 
> See ?R_HOME in R, which tells you that is the R process 'is normally set on startup'.   'Normally' because there are many ways to start R (embedded, for example: see 'Writing R Extensions'), and you have not actually told us how you started R.  But Rgui.exe and Rterm.exe do always set R_HOME.


Notice also that R_HOME represents R's own knowledge of its installation directory, where it looks for various support files, the default package library, etc. 

R sets R_HOME for itself; even if you could, you really do not want to override it. Try looking at ?Startup for the correct ways to specify alternative locations of profile files, etc.

-- 
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com