title: read all filename in directory containing emojis
body: <p>I want to read all file names in a directory which contain some emojis. For instance:</p>
  
  <p>'❤️Geschenk für Sie!❤️.msg'
  'Für Ungeduldige! .msg'
  'Trockene Haut ❄️?.msg'</p>
  
  <p>I've already tried <code>dir("./")</code> and <code>tm::DirSource("./", encoding = "UTF-8")</code></p>
  
  <p><code>dir("./")</code> can read the filenames but returns <code>??</code> instead for the emojis.</p>
  
  <pre><code>&gt; dir("./")
  [1] "??Geschenk für Sie!??.msg" "Für Ungeduldige! ??.msg"      "Trockene Haut ???.msg"
  </code></pre>
  
  <p>And an error occurs with the latter one</p>
  
  <pre><code>&gt; tm::DirSource("./", encoding = "UTF-8")
  Error in tm::DirSource(path.newsletter, encoding = "UTF-8") : 
    non-existent or non-readable file(s): ./??Geschenk für Sie!??.msg ./Für Ungeduldige! ??.msg ./Trockene Haut ???.msg
  </code></pre>
  
  <p>Any help would be much appreciated.</p>