1、passwd 命令，手动修改：
    [root@localhost testuser]# passwd testuser
    Changing password for user testuser.
    New password:
    Retype new password:
    passwd: all authentication tokens updated successfully.
    [root@localhost testuser]#

    2、passwd 命令，命令行修改：
    [root@localhost testuser]# echo ‘!@#$5678’|passwd —stdin testuser

    3、chpasswd 命令，命令行修改
    [root@localhost testuser]# echo ‘testuser:!@#$5678’|chpasswd