title: How to search and replace using grep
body: <p>I need to recursively search for a specified string within all files and subdirectories within a directory and replace this string with another string.</p>
  <p>I know that the command to find it might look like this:</p>
  <pre class="lang-bash prettyprint-override"><code>grep 'string_to_find' -r ./*
  </code></pre>
  <p>But how can I replace every instance of <code>string_to_find</code> with another string?</p>