今天看到了马哥的视频，讲道理passwd命令和管道的标准输入时，一个命令重置密码。
我测试了一下报错
echo "test" | password --stdin test
root@localhost:/home/test2# echo "test" | password --stdin test
未找到 'password' 命令，您要输入的是否是：
命令 'assword' 来自于包 'assword' (universe)
password：未找到命令
root@localhost:/home/test2# echo "test" | passwd --stdin test
passwd：无法识别的选项“--stdin”
Usage: passwd [options] [LOGIN]
Options:
-a,--all report password status on all accounts
-d,--delete delete the password for the named account
-e,--expire force expire the password for the named account
-h,--help display this help message and exit
-k,--keep-tokens change password only if expired
-i,--inactive INACTIVE set password inactive after expiration
to INACTIVE
-l,--lock lock the password of the named account
-n,--mindays MIN_DAYS set minimum number of days before password
change to MIN_DAYS
-q,--quiet quiet mode
-r,--repository REPOSITORY change password in REPOSITORY repository
-R,--root CHROOT_DIR directory to chroot into
-S,--status report password status on the named account
-u,--unlock unlock the password of the named account
-w,--warndays WARN_DAYS set expiration warning days to WARN_DAYS
-x,--maxdays MAX_DAYS set maximum number of days before password
change to MAX_DAYS
我看到这个错误，我以为是passwd --stdin这个参数问题，于是我上网百度了一下，大家都说没问题啊，
意外在Ubuntu论坛中发现了一个帖子
最近学习鸟哥的passwd用法时练习建立账号并修改密码（密码统一为“password”），程序如下
#!/bin/bash
groupadd myquotagrp
for username in myquota1 myquota2 myquota3 myquota4 quota5
do
useradd -g myquotagrp $username
echo "password" | passwd --stdin $username
done
运行后报错
passwd: unrecognized option '--stdin'
Usage: passwd [options] [LOGIN]
Options:
-a,--all report password status on all accounts
-d,--delete delete the password for the named account
-e,--expire force expire the password for the named account
-h,--help display this help message and exit
-k,--keep-tokens change password only if expired
-i,--inactive INACTIVE set password inactive after expiration
to INACTIVE
-l,--lock lock the password of the named account
-n,--mindays MIN_DAYS set minimum number of days before password
change to MIN_DAYS
-q,--quiet quiet mode
-r,--repository REPOSITORY change password in REPOSITORY repository
-S,--status report password status on the named account
-u,--unlock unlock the password of the named account
-w,--warndays WARN_DAYS set expiration warning days to WARN_DAYS
-x,--maxdays MAX_DAYS set maximim number of days before password
change to MAX_DAYS
我又查了下passwd的用法，虽然不是很懂，但尝试了openssl passwd -stdin
还是报错：
Usage: passwd [options] [passwords]
where options are
-crypt standard Unix password algorithm (default)
-1 MD5-based password algorithm
-apr1 MD5-based password algorithm,Apache variant
-salt string use provided salt
-in file read passwords from file
-stdin read passwords from stdin
-noverify never verify when reading password from terminal
-quiet no warnings
-table format output as table
-reverse switch table columns
最后看到了其中一个信息
passwd的--stdin参数ubuntu不支持，其实debian就不支持这个，自己后来在centos7中测试了一下，可以，原理问题就出在这里。
因为我的系统是Ubuntu14.04的系统，终于找到问题的原因了。
后来在网上找到了一个方法就是换行，模拟两次输入密码，但是发现还是不行，
root@localhost:/home/test2# echo "test\ntest" | passwd test2
输入新的 UNIX 密码： 重新输入新的 UNIX 密码： passwd: 认证令牌操作错误
passwd: password unchanged
自己直接重置密码可以。
root@localhost:/home/test2# passwd test2
输入新的 UNIX 密码：
重新输入新的 UNIX 密码：
passwd: password updated successfully
root@localhost:/home/test2#
自己想到这里也没有好的办法了，希望高手也可以留言，帮忙解决一下吧
