Apache may not aware the PATH to R, try 'exec("/pathToR/R CMD ...")'. In addition, apache and R should be in the same physical driver. -Junwen > I've developed a web application in PHP and R > > my script is > > > <?php > > ... > exec("R CMD BATCH --silent /home/marcello/R_in/myfile.bat > /home/marcello/R_out/myfile.out"); >