title: How to use command "at" to execute shell in MacOS
body: <p>I want to execute some shell script once in MacOS.</p>
  
  <p>At first, I tried the "at" command in Ubuntu and it performed well.
  But when I use same method in MacOS, things goes wrong</p>
  
  <p>I typed: </p>
  
  <pre><code>$ at now + 2 minutes
  ls -al &gt; tmpfile
  (ctrl+d,EOF)
  </code></pre>
  
  <p>The job was added successfully. </p>
  
  <p>The output of "at -l" is:</p>
  
  <pre><code>(some other output)
  11         Fri  Jul  19  15:18:00  2013
  </code></pre>
  
  <p>But after 15:18 ,tmpfile was not changed.</p>
  
  <p>I want to know how to use "at" command in MacOS corectly or is there any other method to execute some shell script at certain time once(not periodic)</p>