*http://dev.mysql.com/doc/refman/4.1/ja/resetting-permissions.html
=====Ubuntu 初期パスワードの場所=====
*確認
<pre>
$ sudo cat /etc/mysql/debian.cnf
socket = /var/run/mysqld/mysqld.sock
</pre>
*ログイン
<pre>
piroto@jinmu:/etc/mysql$ mysql -u debian-sys-maint -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 15
Server version: 8.0.21-0ubuntu0.20.04.4 (Ubuntu)
Copyright (c) 2000, 2020, 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>
</pre>
=====mysqldを--skip-grant-tables オプションで起動=====
# mysqld --skip-grant-tables &