1、停止mysql服務

[[email protected] ~]# ps -ef | grep mysql
root       5365      1  0 15:47 pts/0    00:00:00 /bin/sh /usr/local/mysql/bin/mysqld_safe --datadir=/usr/local/mysql/data --pid-file=/usr/local/mysql/data/CentOS.pid
mysql      5452   5365  4 15:47 pts/0    00:00:00 /usr/local/mysql/bin/mysqld --basedir=/usr/local/mysql --datadir=/usr/local/mysql/data --plugin-dir=/usr/local/mysql/lib/plugin --user=mysql --log-error=CentOS.err --pid-file=/usr/local/mysql/data/CentOS.pid
root       5485   5210  0 15:47 pts/0    00:00:00 grep --color=auto mysql
[
 
[email protected] ~]# service mysql stop    # 停止 mysql 服務
Shutting down MySQL.. SUCCESS! 
[[email protected] ~]# 

2、使用 mysqld_safe 來啟動mysql服務

[[email protected] ~]# cd /usr/local/mysql/bin/
[[email protected] bin]# ./mysqld_safe --skip-grant-tables
2018-03-02T07:49:52.491532Z mysqld_safe Logging to '/usr/local/mysql/data/CentOS.err'.
2018-03-02T07:49:52.528458Z mysqld_safe Starting mysqld daemon with databases from /usr/local/mysql/data
 

如上所示，執行 ./mysqld_safe --skip-grant-tables 後會暫停輸出。其中 --skip-grant-tables 選項表示MySql伺服器不載入許可權判斷，任何使用者都能訪問資料庫。

3、然後另外開啟一個終端視窗，免密碼登入mysql

[[email protected] bin]# ./mysql -u root -p
Enter password:                     # 此處為空密碼
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.7.21 MySQL Community Server (GPL)

Copyright (c) 2000, 2018, 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.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> 
 

4、修改 root 密碼

mysql> flush privileges;
Query OK, 0 rows affected (0.01 sec)

mysql> SET PASSWORD FOR 'root'@'localhost' = PASSWORD('root');    # 將 root 密碼修改為 'root'
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql>