1. 關掉mysql服務，打開系統設置最后的mysql,然后將mysql先關掉
2. 生成一個文件命名mysql-init，文件中放入：一句話，這句話不同版本不一樣，如下：（括號里面不包含）
alter user ‘root’@‘localhost’ identified by ‘新密碼’；(MySQL 5.7.6 and later)
set password for ‘root’@‘localhost’=password(‘新密碼’);(MySQL 5.7.5 and earlier)
3. cd /usr/local/mysql/bin/
sudo su
mysqld_safe —init-file=/home/me/mysql-init &
mysqld_safe —skip-grant-tables &
./mysql
flush privileges;
update mysql.user set authentication_string = password(‘你在文件中定義的新密碼’)，password_expired = ’N’ where user = ‘root’ and host = ‘localhost’;
flush privileges;
quit;
./mysql -u root -p
輸入你的新密碼就好了
參考：B.5.3.2.2 Resetting the Root Password: Unix and Unix-Like Systems小節(http://dev.mysql.com/doc/refman/5.7/en/resetting-permissions.html)