[R] X11 connection error in web cgi mode only

Roger Peng rpeng at stat.ucla.edu
Mon Mar 17 18:12:07 CET 2003

I believe you get this error because the jpeg and png libraries require
the X11 device to be open in order to generate the plot.  I'll guess that
if you're doing CGI then the X11 device is not available.  You can try
using the `bitmap' device if you want jpeg or png.  This converts to
jpeg/png from postscript.

UCLA Department of Statistics
rpeng at stat.ucla.edu

On Mon, 17 Mar 2003, Adaikalavan Ramasamy wrote:

> Dear all,
> I am trying to create a web interface using Perl-CGI to call R plots and
> to display them.
> The following codes works perfectly fine when I copy and paste into the
> console directly or if I save it into script.file and then R --no-save <
> script.file producing the graphs. 
> jpeg("graph.jpeg", width=400, height=400)
> plot(rnorm(100))
> dev.off()
> Now, I put the line system("R --no-save < script.file > log_file") from
> inside my cgi and then process it from client side, I get the following
> error message:
> Error in X11(paste("jpeg::", quality, ":", filename, sep = ""), width,
> : 
>         unable to start device JPEG
> In addition: Warning message: 
> unable to open connection to X11 display`' 
> Execution halted
> Why do I get this error and how can I fix it? Many thanks in advance.
> Regards, Adai.
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