Rendering a presentation out of an Org file is a snap when working in Emacs.
On the command line there is an option too by using the batch mode of Emcas:
emacs my-presentation.org -l ~/.emacs.d/init.el -f org-re-reveal-export.to-html
Or have watchmedo help out to automate parts:
watchmedo shell-command -p '*.org' -i '.#*' \ -c 'Emacs "${watch_src_path}" --batch -l ~/.emacs.d/init.el -f org-re-reveal-export-to-html'