環境
- MySQL 14.14
- Vagrant 1.8.1
- CentOS 7.0
内容
MySQLをインストールし，まず以下のコマンドでMySQLサーバを起動
> systemctl start mysqld.service
その後，ログインするときに，
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: N O)
となり，ログインできなかった．
対処
まず，MySQLサーバの停止
> systemctl stop mysqld.service
MySQLをセーフモードで起動
> mysqld_safe --skip-grant-tables &
MySQLにログイン
もう一つコマンドラインを開き，MySQLに接続する
> mysql
ユーザの設定
まず，ユーザの設定を確認してみます．
mysql> use mysql;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
mysql> select * from user;
+-----------+-----------+-------------+-------------+-------------+-------------+-------------+-----------+-------------+---------------+--------------+-----------+------------+-----------------+------------+------------+--------------+------------+-----------------------+------------------+--------------+-----------------+------------------+------------------+----------------+---------------------+--------------------+------------------+------------+--------------+------------------------+----------+------------+-------------+--------------+---------------+-------------+-----------------+----------------------+-----------------------+-------------------------------------------+------------------+-----------------------+-------------------+----------------+
| Host | User | Select_priv | Insert_priv | Update_priv | Delete_priv | Create_priv | Drop_priv | Reload_priv | Shutdown_priv | Process_priv | File_priv | Grant_priv | References_priv | Index_priv | Alter_priv | Show_db_priv | Super_priv | Create_tmp_table_priv | Lock_tables_priv | Execute_priv | Repl_slave_priv | Repl_client_priv | Create_view_priv | Show_view_priv | Create_routine_priv | Alter_routine_priv | Create_user_priv | Event_priv | Trigger_priv | Create_tablespace_priv | ssl_type | ssl_cipher | x509_issuer | x509_subject | max_questions | max_updates | max_connections | max_user_connections | plugin | authentication_string | password_expired | password_last_changed | password_lifetime | account_locked |
+-----------+-----------+-------------+-------------+-------------+-------------+-------------+-----------+-------------+---------------+--------------+-----------+------------+-----------------+------------+------------+--------------+------------+-----------------------+------------------+--------------+-----------------+------------------+------------------+----------------+---------------------+--------------------+------------------+------------+--------------+------------------------+----------+------------+-------------+--------------+---------------+-------------+-----------------+----------------------+-----------------------+-------------------------------------------+------------------+-----------------------+-------------------+----------------+
| localhost | root | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | | | | | 0 | 0 | 0 | 0 | mysql_native_password | *596C07564BAC98CD26D0D1C356CD293F7C605A14 | Y | 2016-03-29 07:55:31 | NULL | N |
| localhost | mysql.sys | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | | | | | 0 | 0 | 0 | 0 | mysql_native_password | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE | N | 2016-03-29 07:55:31 | NULL | Y |
+-----------+-----------+-------------+-------------+-------------+-------------+-------------+-----------+-------------+---------------+--------------+-----------+------------+-----------------+------------+------------+--------------+------------+-----------------------+------------------+--------------+-----------------+------------------+------------------+----------------+---------------------+--------------------+------------------+------------+--------------+------------------------+----------+------------+-------------+--------------+---------------+-------------+-----------------+----------------------+-----------------------+-------------------------------------------+------------------+-----------------------+-------------------+----------------+
2 rows in set (0.00 sec)
今思うと確認はしてませんが，authentication_stringがデフォルトのパスワードなのかも？
ひとまず，全て消してrootユーザを作成します．
mysql> truncate table user;
Query OK, 0 rows affected (0.01 sec)
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)
mysql> grant all privileges on *.* to root@localhost identified by 'password' with grant option;
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)
mysql> select host, user from user;
+-----------+------+
| host | user |
+-----------+------+
| localhost | root |
+-----------+------+
1 row in set (0.01 sec)
flush privilegesで設定の反映を行っていますが，grant文では不要なようです．参考文献
MySQLサーバの起動
先ほどセーフモードで起動していたものをCtrl+Cで止めた後，通常の起動方法で起動します．
> systemctl start mysqld.service
MySQLにログイン
> mysql -u root -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 5
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>
これで接続完了！やったね╮(´･ᴗ･` )╭