PHP how to execute a command

Question

I\'m trying to use LibreOffice for converting a spreadsheet to another format, when I execute the command from the console it works fine but when I do it from PHP using exec

Answer 1

I solved this problem with the command below :

system('
  export HOME=/tmp 
  libreoffice --headless --invisible --norestore --convert-to pdf --outdir /my/folder /my/file/calc.xls');