title: Get date of last saturday - BusyBox 1.1.0
body: <p>Since the date in BusyBox is not as powerful as <em>gnu date</em>, I have problems to calculate the date of last saturday.</p>
  
  <pre><code>last_sat=`date +"%Y-%m-%d" -d "last saturday"`
  </code></pre>
  
  <p>only works fine with gnu date.</p>
  
  <p>I've found something like this to calculate from Epoch</p>
  
  <pre><code>busybox date -D '%s' -d "$(( `busybox date +%s`+3*60 ))"
  </code></pre>
  
  <p>but my BusyBox (v1.1.0) doesn't recognize the <code>-D</code> argument.</p>
  
  <p>Any suggestions?</p>