title: Use of :upper: in bash script for checking if filename contains an uppercase character
body: <p>I came across this piece of bash script for converting filenames which contain an uppercase character into a lowercase name.</p>
  
  <pre><code>LIST="$(ls)"
  
  for name in "$LIST"; do
  
  if [[ "$name" != *[[:upper:]]* ]]; then
  continue
  fi
  #... remainder omitted
  </code></pre>
  
  <p>It's the <code>\*[[:upper:]]\*</code> character class which I am not sure about. Does it read as <em>zero or more characters followed by an upper case letter followed by zero or more characters</em>?  </p>