#!/bin/bash

MATRIX="0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
LENGTH="8"

while [ ${n:=1} -le $LENGTH ]; do
	PASS="$PASS${MATRIX:$(($RANDOM%${#MATRIX})):1}"
	let n+=1
done

echo $PASS