title: Run R script from command line
body: <p>I have a file, called <code>a.r</code>, it has a <code>chmod</code> of 755,</p>
  
  <pre><code>sayHello &lt;- function(){
     print('hello')
  }
  
  sayHello()
  </code></pre>
  
  <p>How can I run this via command-line?</p>