[ESS] help() and library() in R return "... cat: not found"

[Richard M. Heiberger]

This looks like a PATH problem, since you can't find rm and ls, which are
basic unix tools.

Enter 
Sys.getenv("PATH")
at the R prompt.  That will probably give you the clue you need, or the clue
that R-SIG-Mac needs to help solve the problem.

Rich