title: Mac os - brew install unrar fails
body: <p>I'm trying to run <code>brew install unrar</code> on mac os <code>Big Sur</code> and I'm getting the following error:</p>
  <pre><code>Updating Homebrew...
  ==&gt; Auto-updated Homebrew!
  Updated 1 tap (homebrew/cask).
  ==&gt; Updated Casks
  Updated 1 cask.
  
  ==&gt; Searching for similarly named formulae...
  Error: No similarly named formulae found.
  Error: No available formula or cask with the name &quot;unrar&quot;.
  ==&gt; Searching for a previously deleted formula (in the last month)...
  Error: No previously deleted formula found.
  ==&gt; Searching taps on GitHub...
  Error: No formulae found in taps.
  </code></pre>
  <p>Please advise on how I can resolve this.</p>