# test.R
# Parse and use command line arguments
# Invoke % R --slave --args 100 < test.R 

Args <- commandArgs();      # retrieve args
x <- c(1:as.real(Args[4])); # get the 4th argument
y <- c(x^2);                # work out square
png(filename="image.png");  # create image file
plot(x,y);                  # plot image