Pretty good, I use

alias genpass { return $eval($ $+ +( $str($!iif($r(0,1),$iif($r(0,1),$r(A,Z),$r(a,z)),$r(0,9)) $+ $chr(44),$1) ),2) }

it can generate up to a length of 79 characters //echo -b $genpass(9)