mysqld，也称为 MySQL 服务器，是一个单一的多线程程序，在 MySQL 安装中完成大部分工作。它不会生成额外的进程。MySQL 服务器管理对包含数据库和表的 MySQL 数据目录的访问。数据目录也是其他信息（如日志文件和状态文件）的默认位置。mysqld, also known as MySQL Server, is a single multithreaded program that does most of the work in a MySQL installation. It does not spawn additional processes. MySQL Server manages access to the MySQL data directory that contains databases and tables. The data directory is also the default location for other information such as log files and status files.

当 MySQL 服务器启动时，它会监听来自客户端程序的网络连接，并代表这些客户端管理对数据库的访问。When MySQL server starts, it listens for network connections from client programs and manages access to databases on behalf of those clients.

mysqld 程序有许多可以在启动时指定的选项。要查看完整的选项列表，请运行以下命令：The mysqld program has many options that can be specified at startup. For a complete list of options, run this command:

mysqld --verbose --help

MySQL 服务器还有一组系统变量，这些变量在其运行时会影响其操作。系统变量可以在服务器启动时设置，其中很多变量也可以在运行时更改，以实现动态服务器重新配置。MySQL 服务器还有一组状态变量，用于提供其操作的信息。您可以监控这些状态变量以获取运行时的性能特征。MySQL Server also has a set of system variables that affect its operation as it runs. System variables can be set at server startup, and many of them can be changed at runtime to effect dynamic server reconfiguration. MySQL Server also has a set of status variables that provide information about its operation. You can monitor these status variables to access runtime performance characteristics.

有关 MySQL 服务器命令选项、系统变量和状态变量的完整说明，请参阅 7.1 节，“MySQL 服务器”。有关安装 MySQL 和设置初始配置的信息，请参阅 第 2 章，安装 MySQL。For a full description of MySQL Server command options, system variables, and status variables, see Section 7.1, “The MySQL Server”. For information about installing MySQL and setting up the initial configuration, see Chapter 2, Installing MySQL.