[R] Update MS Windows PATH variable based on a R script

Janko Thyson janko.thyson.rstuff at googlemail.com
Thu Dec 8 23:16:17 CET 2011

This is a very very very late follow up, but I remember asking this 
question and just stumbled across an answer by Yihui. Check his file 
'add-R-path-win.R' script which you can find at 

Very cool, thanks Yihui.


On 29.06.2011 20:58, Duncan Murdoch wrote:
> On 29/06/2011 2:24 PM, Janko Thyson wrote:
>> Dear list,
>> this is not directly an R question, but it is somewhat related to R
>> aspects, so I hope it's okay to post it here:
>> I'd like to update my windows PATH based on a script routine in order to
>> make sure that crucial components are contained. Much like what happens
>> at the installation of Rtools (if desired). Now, can you do that from
>> within R or do I need some sort of windows batch file or something like
>> AutoIt script (http://www.autoitscript.com/site/autoit/)? If so, what
>> would I need to put in there?
> You need to set the registry entry if you want a persistent change to 
> the PATH.  Sys.setenv just modifies R's copy of the PATH.  Child 
> processes will see the modifications, but they don't last beyond the R 
> session.
> You'll have to check MS docs to find which registry entry to mess 
> with.  Alternatively, if you feel lucky, just use Control Panel to set 
> some strange path, then see where your change showed up using regedit.
> R doesn't have a built-in function to write to the registry, but there 
> are various utilities available outside of R to do it.
> Duncan Murdoch
>> Here's what I tried in R:
>> unlist(strsplit(Sys.getenv("PATH"), ";"))
>> PATH.0<- Sys.getenv("PATH")
>> PATH.1<- paste(PATH.0, "C:\\blabla\bin")
>> Sys.setenv("PATH"=PATH.1)
>> unlist(strsplit(Sys.getenv("PATH"), ";"))
>> The changes seem to be reflected, but when I check my PATH the new entry
>> isn't there. I guess there is no actual "feedback" to Windows system
>> environment variable and that's exactly what I would like to accomplish
>> Thanks a lot for any advice,
>> Janko
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