Grep not matching regular expression
<p>I'm strugging a bit to get matching results from <code>grep</code>. </p>

<p>Given the following input file's contents</p>

<blockquote>
  <p>{"foo":29, "bar":30}</p>
</blockquote>

<p>and the following command <code>grep -o '"[^"]+":[0-9]+' input.txt</code>, I'm expecting two matching results. As far as I know it supports regular expressions, but I don't understand why <code>grep</code> doesn't return any results?</p>

<p>Other implementations of regexp are working fine (<a href="https://regex101.com/r/RcONXk/1" rel="nofollow">https://regex101.com/r/RcONXk/1</a>).</p>