title: Imagemagick convert command: set delay time for the last frame
body: <p>I have some  .png files named '_tmp*.png' and I want to convert them into a gif file by the convert command with imagemagick. So i could use</p>
  
  <pre><code>convert -delay 20 _tmp*.png result.gif
  </code></pre>
  
  <p>However I want the last frame to hold for a while on screen so that one can see the ending of the animation more clearly. Say, I want the last frame to last for 3 seconds while keeping the delay time for the other frames not changed. I studied the document for the convert command but it seems it does not have such a choice. </p>
  
  <p>So how can I do this with the convert command? </p>