* How to convert office documents to text

You may use libreoffice from terminal to tranform the file in pdf:

#+begin_example sh
  libreoffice --headless --convert-to pdf Presentation.pptx
#+end_example


Then you can use 'pdftotext' command to transform the pdf file to any plain text
format:

#+begin_example sh
  pdftotext Presentation.pdf Presentation.txt
#+end_example