systemd provides automatic MySQL server startup and shutdown. systemd提供自动启动和关闭MySQL服务器。It also enables manual server management using the systemctl command. 它还使用systemctl命令启用手动服务器管理。For example:例如：

shell> systemctl {start|stop|restart|status} mysqld

Alternatively, use the service command (with the arguments reversed), which is compatible with System V systems:或者，使用service命令（参数颠倒），该命令与System V systems兼容：

shell> service mysqld {start|stop|restart|status}

Support for systemd includes these files:对systemd的支持包括以下文件：

To add or change systemd options for MySQL, these methods are available:要添加或更改MySQL的systemd选项，可以使用以下方法：

To use a localized systemd configuration file, create the /etc/systemd/system/mysqld.service.d directory if it does not exist. 要使用本地化的systemd配置文件，请创建/etc/systemd/system/mysqld.service.d目录（如果不存在）。In that directory, create a file that contains a [Service] section listing the desired settings. 在该目录中，创建一个包含[Service]部分的文件，其中列出了所需的设置。For example:例如：

[Service]
LimitNOFILE=max_open_files
Nice=nice_level
LimitCore=core_file_limit
Environment="LD_PRELOAD=/path/to/malloc/library"
Environment="TZ=time_zone_setting"

The discussion here uses override.conf as the name of this file. 这里的讨论使用override.conf作为此文件的名称。Newer versions of systemd support the following command, which opens an editor and permits you to edit the file:较新版本的systemd支持以下命令，该命令可打开编辑器并允许您编辑文件：

systemctl edit mysqld  # RPM platforms
systemctl edit mysql   # Debian platforms

Whenever you create or change override.conf, reload the systemd configuration, then tell systemd to restart the MySQL service:无论何时创建或更改override.conf，请重新加载systemd配置，然后告诉systemd重新启动MySQL服务：

systemctl daemon-reload
systemctl restart mysqld  # RPM platforms
systemctl restart mysql   # Debian platforms

With systemd, the override.conf configuration method must be used for certain parameters, rather than settings in a [mysqld], [mysqld_safe], or [safe_mysqld] group in a MySQL option file:对于systemd，override.conf配置方法必须用于某些参数，而不是MySQL选项文件中[mysqld]、[mysqld_safe]或[safe_mysqld]组中的设置：

For additional information about using systemd rather than mysqld_safe, see Migrating from mysqld_safe to systemd.有关使用systemd而不是mysqld_safe的更多信息，请参阅从mysqld_safe迁移到systemd。

You can set the following parameters in override.conf:您可以在override.conf中设置以下参数：

Some MySQL parameters are configured using environment variables:一些MySQL参数是使用环境变量配置的：

There are multiple ways to specify environment variable values for use by the MySQL server process managed by systemd:有多种方法可以指定由systemd管理的MySQL服务器进程使用的环境变量值：

To specify options for mysqld without modifying systemd configuration files directly, set or unset the MYSQLD_OPTS systemd variable. 要在不直接修改systemd配置文件的情况下为mysqld指定选项，请设置或取消设置MYSQLD_OPTS systemd变量。For example:例如：

systemctl set-environment MYSQLD_OPTS="--general_log=1"
systemctl unset-environment MYSQLD_OPTS

MYSQLD_OPTS can also be set in the /etc/sysconfig/mysql file.MYSQLD_OPTS也可以在/etc/sysconfig/mysql文件中设置。

After modifying the systemd environment, restart the server to make the changes effective:修改systemd环境后，重新启动服务器以使更改生效：

systemctl restart mysqld  # RPM platforms
systemctl restart mysql   # Debian platforms

For platforms that use systemd, the data directory is initialized if empty at server startup. This might be a problem if the data directory is a remote mount that has temporarily disappeared: The mount point would appear to be an empty data directory, which then would be initialized as a new data directory. 对于使用systemd的平台，如果在服务器启动时数据目录为空，则会对其进行初始化。如果数据目录是临时消失的远程装载，则可能会出现问题：装载点似乎是空的数据目录，然后将其初始化为新的数据目录。To suppress this automatic initialization behavior, specify the following line in the /etc/sysconfig/mysql file (create the file if it does not exist):要抑制此自动初始化行为，请在/etc/sysconfig/mysql文件中指定以下行（如果该文件不存在，请创建该文件）：

NO_INIT=true

This section describes how to configure systemd for multiple instances of MySQL.本节介绍如何为多个MySQL实例配置systemd。

To use multiple-instance capability, modify the my.cnf option file to include configuration of key options for each instance. 要使用多实例功能，请修改my.cnf选项文件，以包含每个实例的关键选项配置。These file locations are typical:这些文件位置是典型的：

For example, to manage two instances named replica01 and replica02, add something like this to the option file:例如，要管理名为replica01和replica02的两个实例，请在选项文件中添加如下内容：

RPM platforms:RPM平台：

[mysqld@replica01]
datadir=/var/lib/mysql-replica01
socket=/var/lib/mysql-replica01/mysql.sock
port=3307
log-error=/var/log/mysqld-replica01.log

[mysqld@replica02]
datadir=/var/lib/mysql-replica02
socket=/var/lib/mysql-replica02/mysql.sock
port=3308
log-error=/var/log/mysqld-replica02.log

Debian platforms:Debian平台：

[mysqld@replica01]
datadir=/var/lib/mysql-replica01
socket=/var/lib/mysql-replica01/mysql.sock
port=3307
log-error=/var/log/mysql/replica01.log

[mysqld@replica02]
datadir=/var/lib/mysql-replica02
socket=/var/lib/mysql-replica02/mysql.sock
port=3308
log-error=/var/log/mysql/replica02.log

The replica names shown here use @ as the delimiter because that is the only delimiter supported by systemd.此处显示的副本名称使用@作为分隔符，因为这是systemd支持的唯一分隔符。

Instances then are managed by normal systemd commands, such as:然后，实例由正常的systemd命令管理，例如：

systemctl start mysqld@replica01
systemctl start mysqld@replica02

To enable instances to run at boot time, do this:要使实例在启动时运行，请执行以下操作：

systemctl enable mysqld@replica01
systemctl enable mysqld@replica02

Use of wildcards is also supported. 还支持使用通配符。For example, this command displays the status of all replica instances:例如，此命令显示所有副本实例的状态：

systemctl status 'mysqld@replica*'

For management of multiple MySQL instances on the same machine, systemd automatically uses a different unit file:为了管理同一台机器上的多个MySQL实例，systemd自动使用不同的单元文件：

In the unit file, %I and %i reference the parameter passed in after the @ marker and are used to manage the specific instance. 在单元文件中，%I和%i引用在@标记之后传入的参数，用于管理特定实例。For a command such as this:对于这样的命令：

systemctl start mysqld@replica01

systemd starts the server using a command such as this:systemd使用如下命令启动服务器：

mysqld --defaults-group-suffix=@%I ...

The result is that the [server], [mysqld], and [mysqld@replica01] option groups are read and used for that instance of the service.

Because mysqld_safe is not installed on platforms that use systemd to manage MySQL, options previously specified for that program (for example, in an [mysqld_safe] or [safe_mysqld] option group) must be specified another way: