title: how to chop last n bytes of a string in bash string choping?
body: <p>for example <code>qa_sharutils-2009-04-22-15-20-39</code>, want chop last 20 bytes, and get '<code>qa_sharutils</code>'.</p>
  
  <p>I know how to do it in sed, but why <code>$A=${A/.\{20\}$/}</code> does not work?</p>
  
  <p>Thanks!</p>