#!/bin/bash

C="abcdefghjkmnpqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ23456789!-_"
L=$1
P=""

for (( N=${L:=8}; N--; ))
do
	P="$P${C:$(( $RANDOM%${#C} )):1}"
done

echo $P