1)初始化随机密码 mysqld --initialize
[root@host-172-16-61-102 bin]# ./mysqld --initialize
2020-02-15T07:01:38.309015Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
2020-02-15T07:01:38.309069Z 0 [Warning] 'NO_ZERO_DATE', 'NO_ZERO_IN_DATE' and 'ERROR_FOR_DIVISION_BY_ZERO' sql modes should be used with strict mode. They will be merged with strict mode in a future release.
2020-02-15T07:01:38.497402Z 0 [Warning] InnoDB: New log files created, LSN=45790
2020-02-15T07:01:38.541219Z 0 [Warning] InnoDB: Creating foreign key constraint system
tables.
2020-02-15T07:01:38.553509Z 0 [Warning] No existing UUID has been found, so we assume that this is the first time that this server has been started. Generating a new UUID: 02fb69c1-4fc1-11ea-8b4e-fa163d34f78d.
2020-02-15T07:01:38.556591Z 0 [Warning] Gtid table is not ready to be used. Table 'mysql.gtid_executed' cannot be opened.
2020-02-15T07:01:38.980429Z 0 [Warning] CA certificate ca.pem is self signed.
2020-02-15T07:01:39.723869Z 1 [Note] A temporary password is generated for root@localhost: +:NoRLu2kwhd
生成的密码是：+:NoRLu2kwhd
以上的指令，默认读取配置文件/etc/my.cnf，需要/etc/my.cnf文件中指定了数据库的地址，并且生成一个root用户的密码，还有如下的参数可以设置
--user=mysql //生成指定用户的密码
--datadir=/opt/mysql/mysql/data //指定生成的数据库数据地址
--defaults-file=/opt/mysql/mysql/etc/my.cnf//指定读取的配置文件，取代默认的配置
2)初始化空密码 mysqld --initialize-insecure
启动mysqld服务 ./mysqld --user=root
创建密码
[root@host-172-16-61-102 bin]# mysql -uroot -p
//提示密码输入，直接回车
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MySQL connection id is 11
Server version: 5.7.28 MySQL xxx
Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
//为root创建密码
MySQL [(none)]> set password = password("root");
Query OK, 0 rows affected, 1 warning (0.00 sec)
MySQL [(none)]> quit
注意：执行“mysqld --initialize”报错了。提示“initialize specified but the data directory has files in it. Aborting”，大意是提示/opt/mysql/mysql/data数据库地址下有文件，导致无法初始化数据库，这个时候，可以进入到该目录，将所有的数据删除，说明之前已经初始化过
