title: How to format a number in bash, possibly with printf?
body: <p>This so simple script is failing :</p>
  
  <pre><code>#!/bin/bash
  n=1
  printf -v fn "%05d" $n
  echo $fn
  </code></pre>
  
  <p>with</p>
  
  <pre><code>3: printf: Illegal option -v
  </code></pre>
  
  <p>WHY !!! (ubuntu 14.04)</p>