Short random hash \ string for UIDs,URIs, etc.

randuid.php

<?php

function randuid($len = 8)
{
  $uid = '';
  do {
    $uid .= base_convert(random_int(PHP_INT_MIN, PHP_INT_MAX), 10, 36);
    $uid .= strtoupper(base_convert(random_int(PHP_INT_MIN, PHP_INT_MAX), 10, 36));
  } while(strlen($uid) < $len * 2);
  $uid = substr(str_shuffle($uid), 0, $len);

  return $uid;  
}