title: How to merge images in command line?
body: <p>I would like to try the <a href="http://www.w3schools.com/css/css_image_sprites.asp">CSS Sprite</a> technique to load a few thumbnails as a single image. So I need to "merge" a few thumbnails in a single file offline in the server. </p>
  
  <p>Suppose I have 10 thumbnails of the same size. How would you suggest I "merge" them from Linux command line?</p>