title: find with regex and fixed quantifier
body: <p>I have files in format <code>name with spaeces.xxx.txt</code> where <code>xxx</code> are three digits. I want to match them with <code>find</code>. I have tried:</p>
  
  <pre><code>find . -maxdepth 1 -type f -regex '.*\.[0-9]{3}\.txt'
  </code></pre>
  
  <p>but that does not work. 
  This does not work either:</p>
  
  <pre><code>find . -maxdepth 1 -type f -regex '.*[0-9]{3}\.txt'
  </code></pre>
  
  <p>This one:</p>
  
  <pre><code>find . -maxdepth 1 -type f -regex '.*[0-9]\.txt'
  </code></pre>
  
  <p>works and it seems there is a problem with repeat operator. I tested the regex in online testers and it does match my filenames. I have tried o change <code>-regextype</code> to a few values without any luck. The manual says that by default, <code>find</code> uses <code>emacs</code> style regex, the wiki for <code>emacs</code> says it does know the fixed quantifier, so I am lost.</p>
  
  <p>What am I doing wrong?</p>