Empty pdf

Dear all,

I am comparing "R CMD BATCH script.R" with running the following code 
snippet within R:

pdf("Rplots.pdf")
source("script.R")
dev.off()
q(save="no")

Among other things, one difference is that the former produces no 
Rplots.pdf while the latter produces an empty Rplots.pdf, if script.R 
does not contain "plotting" commands (R version 3.0.1, i486-pc-linux-gnu 
(32-bit)). What is the difference between the two with respect to pdf 
plotting?

Best regards
Adrian

Dr. Adrian Trapletti
Steinstrasse 9b
CH-8610 Uster
Switzerland

Phone : +41 (0) 44 9945630
Mobile : +41 (0) 79 1037131

Email : adrian at trapletti.org
WWW : www.trapletti.org