Mysql 登录，修改密码问题？

官网下载的 mysql-5.7.10-osx10.10-x86_64.dmg 文件，安装好之后。
在.zshrc 中配置了环境变量。
输入这个命令
➜ /Users/gang >mysql -u root -p password 123456

mysql Ver 14.14 Distrib 5.7.10, for osx10.9 (x86_64) using EditLine wrapper
Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Usage: mysql [OPTIONS] [database]
...

输入
mysql -u root -p password 123
也能也出来

mysql Ver 14.14 Distrib 5.7.10, for osx10.9 (x86_64) using EditLine wrapper
Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.

执行
mysqladmin -u root -p

也是同样的

修改密码
mysqladmin -u root -p password 123456

Enter password:
mysqladmin: connect to server at 'localhost' failed
error: 'Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2)

刚安装的，不默认没有密码么？
baidu,google 都解决不了。
求解决，感谢🙏