昨天在centos下安裝mysql5.7後，卻發現無法登陸，才新安裝的mysql，初始密碼應該沒有，但是無論如何都無法登陸（提示密碼錯誤），沒辦法，只好強行修改mysql密碼。

輸入

[[email protected] bin]# mysqld_safe --skip-grant-tables &

這句話相當於進入mysql的安全模式。

輸入上面這條命令可能會出現錯誤如下：

[3] 7135
[2]   Exit 127                mysqld_stae --skip-grant-tables
[[email protected] bin]# Usage: grep [OPTION]... PATTERN [FILE]...
Try `grep --help' for more information.
grep: write error: Broken pipe
2016-04-02T10:16:02.306271Z mysqld_safe Logging to '/opt/mysql/data/localhost.localdomain.err'.
2016-04-02T10:16:02.315564Z mysqld_safe The file /usr/local/mysql/bin/mysqld
does not exist or is not executable. Please cd to the mysql installation
directory and restart this script from there as follows:
./bin/mysqld_safe&
See http://dev.mysql.com/doc/mysql/en/mysqld-safe.html for more information

[3]+  Exit 1                  mysqld_safe --skip-grant-tables
 

建立好資料夾後，準備開啟mysql，但是在這之前先檢查一下mysql是否開啟

[[email protected] ~]# ps -ef|grep mysqld

如果開啟使用kill -15 [pid]殺死mysql。如下：

[[email protected] ~]# ps -ef|grep mysqld
root      6946     1  0 18:15 ?        00:00:00 /bin/sh /opt/mysql/bin/mysqld_safe --datadir=/opt/mysql/data --pid-file=/opt/mysql/data/localhost.localdomain.pid
mysql     7104  6946  0 18:15 ?        00:00:00 /opt/mysql/bin/mysqld --basedir=/opt/mysql --datadir=/opt/mysql/data --plugin-dir=/opt/mysql/lib/plugin --user=mysql --log-error=/opt/mysql/data/localhost.localdomain.err --pid-file=/opt/mysql/data/localhost.localdomain.pid --port=3306
root      7558  7542  0 18:22 pts/0    00:00:00 grep mysqld
[
 
[email protected] ~]# kill -15 7104

再次使用      ps -ef|grep mysqld       確認mysql已經被殺死 

開啟mysql，如下：

[[email protected] ~]# mysqld_safe --skip-grant-tables &
[1] 7566
[[email protected] ~]# 2016-04-02T10:23:22.463266Z mysqld_safe Logging to '/opt/mysql/data/localhost.localdomain.err'.
2016-04-02T10:23:22.514395Z mysqld_safe Starting mysqld daemon with databases from /opt/mysql/data
mysql
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.11 MySQL Community Server (GPL)

Copyright (c) 2000, 2016, 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> UPDATE mysql.user SET authentication_string=password('YourPassword') WHERE User='root'  AND Host='localhost';

好了，測試一下用新密碼能不能進入：

[[email protected] ~]# mysql -uroot -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 6
Server version: 5.7.11

Copyright (c) 2000, 2016, 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> 

一定要注意以前的password變成了authentication_string