---Arch Linux: install mysql 8.x

Under  Arch Linux, install mysql 8
==========================

$ sudo pacman -S mysql 
$ sudo systemctl start mysql.service  (启动失败)
$journalctl -xeu mysqld.service

arch linux mysql   Table 'mysql.plugin' doesn't exist  Please perform the MySQL upgrade procedure

solution:
   清除目录: /var/lib/mysql 内容, 就好了
   sudo mysqld --initialize --user=mysql

跟着测试用空密码就不能登录:
      mysql -uroot -p   

    "sudo mysqld --initialize --user=mysql"  的时候给了一次性密码,   需要立即修改密码
你用它登录后马上改密码就ok了
mysql -uroot -p"${defaultmysqlpwd}" --connect-expired-password <<...EOF...
ALTER USER 'root'@'localhost' IDENTIFIED BY "$newmysqlpwd";
...EOF...

 ref:
https://unix.stackexchange.com/questions/669809/problem-running-mysql-in-arch-linux
   ==> https://dev.mysql.com/doc/refman/5.7/en/data-directory-initialization.html#data-directory-initialization-overview