Using php exec function in Ubuntu does not work

Question

I have the following issue I am using Ubuntu and I am using a simple libreOffice conversion command

$command_conversion = 'libreoffice --headless --convert-to pdf:writer_pdf_Export --outdir /home/stilian/Desktop /home/stilian/Desktop/sample.doc';

exec($command_conversion. $output);

The command is working fine in the terminal but not when I open the webpage to execute the command. I also double checked for errors in the command there are none. also the variable $output is an empty array. Any suggestions would be appriciated.

Answer 1

Change dot by comma

$command_conversion = 'libreoffice --headless --convert-to pdf:writer_pdf_Export --outdir /home/stilian/Desktop /home/stilian/Desktop/sample.doc';

exec($command_conversion, $output);