title: bash script: how to insert text between two specific characters
body: <p>For example, I have a file containing a line as below:<br></p>
  
  <pre><code>"abc":"def"
  </code></pre>
  
  <p>I need to insert <code>123</code> between <code>"abc":"</code> and <code>def"</code> so that the line will become: <code>"abc":"123def"</code>.</p>
  
  <p>As <code>"abc"</code> appears only once so I think I can just search it and do the insertion.<br></p>
  
  <p>How to do this with bash script such as <code>sed</code> or <code>awk</code>?</p>