[R] Calling R from a non-X shell script to plot?

[doktora v]

I am trying to run R from an apache C++ module in a shell script to
plot some data to display it in apache later. I get the error
(reported in apache's logs):

Xlib: connection to ":0.0" refused by server
Xlib: No protocol specified
Error in X11(paste("png::", filename, sep = ""), width, height, pointsize,  :
  unable to start device PNG
In addition: Warning message:
unable to open connection to X11 display`'
Execution halted

Is anyone familiar with this (i.e. running R from a non-X
environment)? Is there  a way to get around this? I've seen some stuff
about virtual devices,  but have no idea if it works or where to
start. If there is a simpler solution, please let me know.

-- doktora


I run the following shell script from the apache module using execve:
------------------------------------------------------
DISPLAY=:0.0
export DISPLAY

if $R --vanilla --quiet < $rfile >$log ; then
  echo "Success"
else
  echo "There were errors in $0, see $log"
fi
------------------------------------------------------

And $rfile contains this:
------------------------------------------------------
png(filename = "/tmp/plot.png", width = 510, height = 360);
plot(<some graph>)
dev.off()