[R] R doesn't recognize R_HOME value

peter dalgaard pdalgd at gmail.com
Wed Jul 25 10:14:59 CEST 2012

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

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