On Wednesday 25 November 2009, Barry Rowlingson wrote: > On Wed, Nov 25, 2009 at 8:15 PM, Dylan Beaudette > > <debeaude...@ucdavis.edu> wrote: > > Hi, > > > > I am trying to transition a system based on dynamic image generation (via > > R) from our development system to a production environment. Our R script > > functions as expected when run by a regular user. However the script dies > > when calling the png() function, when started by the webserver user. > > > > Here are some details > > > >>sessionInfo() > > > > R version 2.9.2 (2009-08-24) > > i686-pc-linux-gnu > > locale: > > C > > attached base packages: > > [1] stats graphics grDevices utils datasets methods base > > > > The script gets to this line: > > > > png(file=filename, width=600, height=400) > > > > and then dies. It leaves an empty PNG file where it should be, however it > > never finishes the file. If > > > > I replace png() with pdf() an output file is generated and closed by > > dev.off() as expected. > > > > It seems like the environment is setup just as when started by a regular > > user, specifically the LD_LIBRARY_PATH variable. > > > > This behavior suggests that R is encountering an error, and stopping. > > However there is no reporting of the error. Is there any way to get more > > verbose error reporting? > > How is R run from your web server? Does it start a new R process or > is it an apache module thing with a dynamically linked R (if such a > thing even exists)? Can't figure out how you could get more error > reporting without knowing that - you need to see where stderr is > going, possibly to the apache error.log file - have you looked there? > > Have you tried a trivial png generating example, just a three liner: > > png(file="/tmp/wherever/foo.png") > plot(1:10) > dev.off() > > just in case it's something else previous in your script that's > breaking things. > > In the old days of R you needed an X11 display connection to do PNG > graphics, but that was fixed before 2.9, I think. Try it interactively > but unset the DISPLAY variable first: > > export -n DISPLAY > R > > > png(... etc etc) > > Does that work? > > Barry
Hi Barry thanks for the tips. I was able to get more error reporting by placing the png() function inside of try(). Turns out this was an X11 related problem-- probably an unset DISPLAY variable for the www user. For the record, R was being run by PHP. I just realized that R was not compiled with Cairo support-- fixing this should make the problems go away... Cheers, Dylan -- Dylan Beaudette Soil Resource Laboratory http://casoilresource.lawr.ucdavis.edu/ University of California at Davis 530.754.7341 ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
