title: How to evaluate all code blocks when exporting in emacs org-mode
body: <p>I have an <code>org-mode</code> document with many different R source code blocks.  Whenever I hit <kbd>C-c C-e</kbd> and export to PDF or HTML I get a different prompt asking to evaluate each code block.  This wasn't a big deal, but now I have to type <code>yes</code> 20+ times.  Is there an option to automatically evaluate all the code blocks?</p>