Are you sure you want the ~ in front of the matches? This makes your test to always succeed; if the match succeeds, the result of the ~/pattern/ is 4294967294 or 18446744073709551614 depending whether you have 32 or 64 bit integers. If the match fails, ~/pattern/ is 4294967295 or 18446744073709551615, depending on the bit size of your integers. All these values are true values.