[R] how can I write code to detect whether the machine is Windows or Linux?

[Philip James Smith]

Hi R-People:

I use 2 machines: a machine with a Windows XP operating system, and 
another with a Linux Ubuntu OS. I transport my code between these 2 
machines. However, pathnames to data files always need to be "adjusted" 
to account for the OS that I'm working on.

Here is my question:

How do I write code to detect whether I'm using the XP or the Linux 
machine?

If I knew this, I could write my code in a way so that I didn't have to 
adjust path names to data file all the time.

I checked the archives... didn't find anything, but perhaps didn't know 
the right search terms...

Thanks for your help, R-community! Please respond to: 
philipsmith at alumni.albany.edu

Best regards,
Phil Smith
Duluth, GA