How to run R through PHP with exec?

Question

I am going to ask something, that I know that it has been asked already some times. But since, all of the past posts are quite old and none of them answer my problem..I try again. I am completely new in R language and relative new in php. What I want to do is to use the exec() function from php in order to execute a R script. Most of the people here will start talking about rapache, rserve and I don't know what else..but since I am not familiar with all these technologies, I prefer just using exec.

The code I will show here is working just fine when I run it with Rscript from the terminal. # R script png("temp.png") plot(5,5) dev.off()

But when I try to run it either with Rscript or with R CMD BATCH from PHP, like this:

       echo exec("Rscript my_rscript.R"); //OR
       //echo exec("R CMD BATCH my_rscript.R");

I get nothing back.

I have checked if exec() function is available and if it works. Everything is ok with this. I read also, that I might have to change the permissions of the webserver...but I don't know how to do this in mamp.

I hope I am clear with my problem and someone can help.

Thanks Dimitris

Answer 1

Not sure if this works for images, but I got nothing back until I stored the results in the second parameter of the exec() function

exec("Rscript test.R $N", $results);
print_r($results);

Answer 2

This worked for me to get the image saved to directory and visible on the web page. From the command line:

chown www-data:www-data /usr/bin/Rscript
chown www-data:www-data -R /PATH/TO/RSCRIPTFOLDER

Changed permissions first on the Rscript executable, and then did the same for the entire folder that houses the .php file, .R file, etc.