urpass.sh

#! /bin/bash
SRC=/dev/urandom


len=${1-12}
i=1

while (( $i <= len )); do
  if (( ($i + 1) % 3 == 0 )) ; then
    cat $SRC | base64 | tr -dc aeiouy | head -c1
  elif (( ($i - 1) % 6 == 0 )); then
    cat $SRC | base64 | tr -dc QWTYPSDFGHJKLZXCVBNMY | head -c1
  else
    cat $SRC | base64 | tr -dc qwrtpsdfghjklzxcvbnm | head -c1
  fi
  (( $i > 0 )) && (($i < len)) && (( $i % 6 == 0 )) && echo -n "-"
  i=$(( $i + 1 ))
done

echo