/******************************************************************************
* Busybox shell脚本修改密码
* 说明：
* 需要在在Busybox文件系统中修改密码，但是passwd命令需要交互才能修改密码，
* 原来Busybox提供了chpasswd命令，在shell中直接用passwd也是可行的。
*
* 2017-3-9 深圳 南山平山村 曾剑锋
*****************************************************************************/
一、参考文档：
1. how to change password with shell script in busybox 1.4.2
http://www.avrfreaks.net/forum/how-change-password-shell-script-busybox-142
2. How do you change a user password in a script with busybox and openssl?
http://*.com/questions/2059069/how-do-you-change-a-user-password-in-a-script-with-busybox-and-openssl
3. How to set a new password from bash?
http://unix.stackexchange.com/questions/26738/how-to-set-a-new-password-from-bash
二、passwd帮助：
[zengjf@root ~]# passwd -h
passwd: invalid option -- 'h'
BusyBox v1.25.0 (2016-09-21 23:53:28 CST) multi-call binary.
Usage: passwd [OPTIONS] [USER]
Change USER's password (default: current user)
-a ALG Encryption method
-d Set password to ''
-l Lock (disable) account
-u Unlock (enable) account
[zengjf@root ~]#
三、解决办法：
1. 方法1： compile your own busybox configuration with chpasswd command。
2. 方法2：
1. 编写一个脚本如下：
#!/bin/sh
passwd << EOF
<new password>
<new password>
EOF
2. 输出效果如下
[zengjf@root ~]# ./chpasswd
Changing password for root
New password:
Bad password: too weak
Retype password:
passwd: password for root changed by root
[zengjf@root ~]#
