很多MIS人員常常為了設定公司員工的密碼，而想不出一個簡單的方法；Ben老師在 課堂上給學員的作業便是，請各位學員使用bash寫出一個密碼產生器。

#!/bin/bash

declare -i count=0
chars='1234567890abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOQPRSTUVWXYZ._!@#$%^&*()'
declare -i chars_length=`expr length $chars`
while [ $count -le 7 ]
do
declare -i pos=`expr $RANDOM % $chars_length`+1

#Double quotation mark is necessary otherwise the following current directory files will be presented if echo is ‘*’:
echo -n "`expr substr $chars $pos 1`"
count=$count+1
done
echo