title: script for changing prefix of filename in bash
body: <p>From</p>
  
  <pre><code>abcd_if_vb.c
  abcd_if_av.c
  </code></pre>
  
  <p>to</p>
  
  <pre><code>edfg_if_vb.c
  edfg_if_av.c
  </code></pre>
  
  <p>The problem is to catch what file have <code>abcd</code> prefix.</p>