~$ mysql -u root -p
Enter password: 
ERROR 1698 (28000): Access denied for user 'root'@'localhost'

~$ sudo service mysql stop

~$ sudo mysqld_safe --skip-grant-tables &

~$ mysql -u root
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.10 MySQL Community Server (GPL) 

mysql> select user, plugin from mysql.user;
+-----------+-----------------------+
| user   | plugin        |
+-----------+-----------------------+
| root   | auth_socket      |
| mysql.sys | mysql_native_password |
| dev    | mysql_native_password |
+-----------+-----------------------+
<strong>3</strong> rows in set (<strong>0.01</strong> sec)

mysql> update mysql.user set authentication_string=PASSWORD('newPwd'), plugin='mysql_native_password' where user='root';
Query OK, <strong>1</strong> row affected, <strong>1</strong> warning (<strong>0.00</strong> sec)
Rows matched: <strong>1</strong> Changed: <strong>1</strong> Warnings: <strong>1</strong>
mysql> flush privileges;
Query OK, <strong>0</strong> rows affected (<strong>0.00</strong> sec)

~$ sudo service mysql stop
...
 * MySQL Community Server 5.7.10 is stopped
~$ sudo service mysql start
..
 * MySQL Community Server 5.7.10 is started
~$ mysql -u root -p
Enter password: 
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.10 MySQL Community Server (GPL)