Ulrik Stervbo wrote:
> Hello!
>
> I am having issues trying to plot to a ong (or jpg) when the R-code in a
> bash script is executed from cron.
>
> I can generate a pdf file, but when I try to write to a png, the file is
> created, but nothing is written. If I execute the bash script from my
> console, everything works file. Any ideas?
>
> In my cron I have SHELL=/bin/bash - otherwise /bin/shell is used and the
> folowing enery, so example is executed every minute
> * * * * * [path]/example.sh
>
> I am running
> R version 2.4.1 (2006-12-18)
>
> Here's a minimal example - two files one R-script
('example.r') and one
> bash-script ('example.sh')
>
> example.r
> # Example R-script
> x <- c(1:10)
> y <- x^2
> png(file="example2.png")
> #pdf(file="example2.pdf")
> plot(x,y)
> graphics.off()
>
> example.sh
> #/bin/bash
> #
> # Hello world is written to exhotext every time cron executes this script
> echo "Hello world" > echotext
> # This works, but not when executed from cron
> n=`R --save < example.r`
> # using exec as in `exec R --save < example.r` dosent work with cron
either
> # This also works, but nothing is written to the png when executed
from cron
> R --save <<RSCRIPT
> x <- c(1:10)
> y <- x^2
> png(file="example2.png")
> #pdf(file="example2.pdf")
> plot(x,y)
> graphics.off()
> #dev.off() dosent work at all when executed from cron
> RSCRIPT
The png() device requires an X server for the image rendering. You might
be able to get away with exporting the DISPLAY environment variable
export DISPLAY=:0.0 # try and connect to X server on display 0.0
within your script, but it will only work if the script is executed by
the same user as is running the X server, *and* the X server is running
at the time the script is executed.
There are a handful of packages that will create a png without the
presence of an X server, and I'm partial to Cairo (since I've done some
work on it). You can install the latest version like this:
install.packages("Cairo",,'http://rforge.net/',type='source')
Cairo can also outputs nice pdf's with embedded fonts... useful if you
want to embed high-quality OpenType or TrueType fonts.
Best,
Jeff
--
http://biostat.mc.vanderbilt.edu/JeffreyHorner