  MATRIX="abcdefghijkmnopqrstuvwxyz" # On peut commencer par n'importe quelle lettre
  LENGTH="5"   # ==> You may change 'LENGTH' for a longer password.
  n=1
  while [ "${n:=1}" -le "$LENGTH" ] 
  do
    LETTER="${MATRIX:$(($RANDOM%${#MATRIX})):1}"

    case "$LETTER" in
      [auiou])
          MATRIX="bcdfghjklmnprstvxz"
          ;;
      [bcdfghjklmnprstvxz])
          MATRIX="auiou"
    esac

    PASS=$PASS$LETTER
    let n+=1
  done
echo $PASS
