title: How to get rid of `grep: warning: GREP_OPTIONS is deprecated; please use an alias or script`?
body: <p>I have zsh + zprezto installed on my Arch linux. Every time I open the console the annoying warning is being displayed:  </p>
  
  <pre><code>grep: warning: GREP_OPTIONS is deprecated; please use an alias or script
  </code></pre>
  
  <p>Following the instructions in <a href="https://bbs.archlinux.org/viewtopic.php?id=190262" rel="noreferrer">[SOLVED] grep: warning: GREP_OPTIONS is deprecated</a> doesn't help. How can I get rid of this warning?</p>