mysql8.0卸载，安装5.6报错，error: Can't open and lock privilege tables: Table 'mysql.user' doesn't exist

本来初始化配置是这样的：

scripts/mysql_install_db --basedir=/usr/local/mysql --datadir=/usr/local/mysql/data --user=mysql

出现了

[root@localhost mysql-5.6.14]# service mysql restart
 ERROR! MySQL server PID file could not be found!
Starting MySQL. ERROR! The server quit without updating PID file (/var/lib/mysql/localhost.localdomain.pid).

在日志中出现了如下错误：

Can't open and lock privilege tables: Table 'mysql.user' doesn't exist

后来采用了下面的语句就可以了：

scripts/mysql_install_db --basedir=/usr/local/mysql --datadir=/usr/local/mysql/data --user=mysql --ldata=/var/lib/mysql