[R-SIG-Mac] R.app cannot see tar but R (console) can

[Ross.Darnell at csiro.au]

If I run

> system('tar')
within the console version of R I get

> system('tar')
tar: Must specify one of -c, -r, -t, -u, -x

If I try using R.app  I get

R version 2.13.1 (2011-07-08)
Copyright (C) 2011 The R Foundation for Statistical Computing
ISBN 3-900051-07-0
Platform: x86_64-apple-darwin9.8.0/x86_64 (64-bit)

R is free software and comes with ABSOLUTELY NO WARRANTY.
You are welcome to redistribute it under certain conditions.
Type 'license()' or 'licence()' for distribution details.

  Natural language support but running in an English locale

R is a collaborative project with many contributors.
Type 'contributors()' for more information and
'citation()' on how to cite R or R packages in publications.

Type 'demo()' for some demos, 'help()' for on-line help, or
'help.start()' for an HTML browser interface to help.
Type 'q()' to quit R.

[R.app GUI 1.41 (5874) x86_64-apple-darwin9.8.0]

[Workspace restored from /Users/dar143/.RData]
[History restored from /Users/dar143/.Rapp.history]

> system(tar)
Error in system(tar) : non-empty character argument expected

Same problem running R within Emacs/ESS
So the  path for tar is not known to R.app.  What is the best way to fix this?

Regards
Ross Darnell