title: How to replace a whole line with sed?
body: <p>Suppose I have a file with lines</p>
  <pre><code>aaa=bbb
  </code></pre>
  <p>Now I would like to replace them with:</p>
  <pre><code>aaa=xxx
  </code></pre>
  <p>I can do that as follows:</p>
  <pre><code>sed &quot;s/aaa=bbb/aaa=xxx/g&quot;
  </code></pre>
  <p>Now I have a file with a few lines as follows:</p>
  <pre><code>aaa=bbb
  aaa=ccc
  aaa=ddd
  aaa=[something else]
  </code></pre>
  <p>How can I replace <em>all</em> these lines <code>aaa=[something]</code> with <code>aaa=xxx</code> using <em>sed</em>?</p>