$re = '/^.*([A-Za-z0-9]{24}).*$/im';
$str = '/v1/api2/5eb98050122d484001708a11f
/v1/api1/5eb98050122d484001708a11f/61b3330151e541232146bfb7/';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php