passwd

设置或修改系统用户密码

[root@poppy ~]# passwd poppy
Changing password for user poppy.
New password:
Retype new password:
passwd: all authentication tokens updated successfully.

用户自己修改

输入旧密码验证，然后输入新密码，设置新密码

[poppy@poppy ~]$ passwd
Changing password for user poppy.
Changing password for poppy.
(current) UNIX password:
New password:
Retype new password:
passwd: all authentication tokens updated successfully.

非交互式修改密码

将poppy用户的密码设置为alvin

[root@poppy ~]# echo alvin|passwd --stdin poppy
Changing password for user poppy.
passwd: all authentication tokens updated successfully.