[R-SIG-Mac] Run C functions in R in Mac

[Bodhisattva Sen]

I have recently installed R 2.4 in my Intel based MacBook laptop. I want 
to access C functions from R source files (*.R files). Earlier I was using 
the commands

system('R CMD SHLIB file_name.c')
dyn.load('file_name.so')

in Linux based machines and it was working. But in the Mac machine the 
same command gives a warning messege

"Library/Framework/R.framework/Resources/bin/SHLIB : line 1 make: 
command not found" along with an error in dyn.load(...).

I would like to know what is the analogous command in Mac based R package.

Thank you,
Bodhisattva