mysqld_multi 旨在管理多个 mysqld 进程，这些进程监听不同的 Unix 套接字文件和 TCP/IP 端口上的连接。它可以启动或停止服务器，或者报告它们的当前状态。mysqld_multi is designed to manage several mysqld processes that listen for connections on different Unix socket files and TCP/IP ports. It can start or stop servers, or report their current status.

mysqld_multi 会在 my.cnf（或在 --defaults-file 选项指定的文件中）查找名为 [mysqldN] 的分组。N 可以是任何正整数。以下讨论中，这个数字称为选项组编号，或 GNR。组编号用于区分不同的选项组，并作为 mysqld_multi 的参数，指定要启动、停止或获取状态报告的服务器。列在这些组中的选项与用于启动 mysqld 时在 [mysqld] 组中使用的选项相同。（例如，请参见 第 2.9.5 节，“自动启动和停止 MySQL”。）然而，当使用多个服务器时，每个服务器必须使用自己独有的选项值，例如 Unix 套接字文件和 TCP/IP 端口号。有关在多服务器环境中哪些选项必须唯一的更多信息，请参见 第 7.8 节，“在一台机器上运行多个 MySQL 实例”。mysqld_multi searches for groups named [mysqldN] in my.cnf (or in the file named by the --defaults-file option). N can be any positive integer. This number is referred to in the following discussion as the option group number, or GNR. Group numbers distinguish option groups from one another and are used as arguments to mysqld_multi to specify which servers you want to start, stop, or obtain a status report for. Options listed in these groups are the same that you would use in the [mysqld] group used for starting mysqld. (See, for example, Section 2.9.5, “Starting and Stopping MySQL Automatically”.) However, when using multiple servers, it is necessary that each one use its own value for options such as the Unix socket file and TCP/IP port number. For more information on which options must be unique per server in a multiple-server environment, see Section 7.8, “Running Multiple MySQL Instances on One Machine”.

要调用 mysqld_multi，请使用以下语法：To invoke mysqld_multi, use the following syntax:

mysqld_multi [options] {start|stop|reload|report} [GNR[,GNR] ...]

start、stop、reload（停止并重启）以及 report 表示要执行的操作。您可以根据选项名称后面的 GNR 列表，对单个服务器或多个服务器执行指定操作。如果没有列表，mysqld_multi 将对选项文件中的所有服务器执行该操作。start, stop, reload (stop and restart), and report indicate which operation to perform. You can perform the designated operation for a single server or multiple servers, depending on the GNR list that follows the option name. If there is no list, mysqld_multi performs the operation for all servers in the option file.

每个 GNR 值表示一个选项组编号或一系列组编号。该值应为选项文件中组名称末尾的数字。例如，名称为 [mysqld17] 的组的 GNR 是 17。要指定一个数字范围，请用短横线分隔起始和结束数字。GNR 值 10-13 表示组 [mysqld10] 到 [mysqld13]。命令行上可以指定多个组或组范围，用逗号分隔。GNR 列表中不能有空白字符（空格或制表符）；空白字符之后的内容将被忽略。Each GNR value represents an option group number or range of group numbers. The value should be the number at the end of the group name in the option file. For example, the GNR for a group named [mysqld17] is 17. To specify a range of numbers, separate the first and last numbers by a dash. The GNR value 10-13 represents groups [mysqld10] through [mysqld13]. Multiple groups or group ranges can be specified on the command line, separated by commas. There must be no whitespace characters (spaces or tabs) in the GNR list; anything after a whitespace character is ignored.

此命令使用选项组 [mysqld17] 启动单个服务器：This command starts a single server using option group [mysqld17]:

mysqld_multi start 17

此命令停止多个服务器，使用选项组 [mysqld8] 和 [mysqld10] 到 [mysqld13]：This command stops several servers, using option groups [mysqld8] and [mysqld10] through [mysqld13]:

mysqld_multi stop 8,10-13

关于如何设置选项文件的示例，可以使用以下命令：For an example of how you might set up an option file, use this command:

mysqld_multi --example

mysqld_multi 按如下方式搜索选项文件：mysqld_multi searches for option files as follows:

有关这些选项文件及其他选项文件选项的更多信息，请参见 第 6.2.2.3 节，“影响选项文件处理的命令行选项”。For additional information about these and other option-file options, see Section 6.2.2.3, “Command-Line Options that Affect Option-File Handling”.

读取的选项文件会搜索 [mysqld_multi] 和 [mysqldN] 选项组。[mysqld_multi] 组可用于 mysqld_multi 本身的选项。[mysqldN] 组可用于传递给特定 mysqld 实例的选项。Option files read are searched for [mysqld_multi] and [mysqldN] option groups. The [mysqld_multi] group can be used for options to mysqld_multi itself. [mysqldN] groups can be used for options passed to specific mysqld instances.

[mysqld] 或 [mysqld_safe] 组可以用于所有 mysqld 或 mysqld_safe 实例读取的通用选项。您可以指定 --defaults-file=file_name 选项来为该实例使用不同的配置文件，在这种情况下，该实例将使用该文件中的 [mysqld] 或 [mysqld_safe] 组。The [mysqld] or [mysqld_safe] groups can be used for common options read by all instances of mysqld or mysqld_safe. You can specify a --defaults-file=file_name option to use a different configuration file for that instance, in which case the [mysqld] or [mysqld_safe] groups from that file are used for that instance.

mysqld_multi 支持以下选项。mysqld_multi supports the following options.

关于 mysqld_multi 的一些笔记：Some notes about mysqld_multi:

下面的示例展示了如何设置一个选项文件以供 mysqld_multi 使用。mysqld 程序启动或停止的顺序取决于它们在选项文件中出现的顺序。组号不必形成连续序列。在示例中故意省略了第一个和第五个 [mysqldN] 组，以说明选项文件中可以存在 “空隙”。这为您提供了更多的灵活性。The following example shows how you might set up an option file for use with mysqld_multi. The order in which the mysqld programs are started or stopped depends on the order in which they appear in the option file. Group numbers need not form an unbroken sequence. The first and fifth [mysqldN] groups were intentionally omitted from the example to illustrate that you can have “gaps” in the option file. This gives you more flexibility.

# This is an example of a my.cnf file for mysqld_multi.
# Usually this file is located in home dir ~/.my.cnf or /etc/my.cnf

[mysqld_multi]
mysqld     = /usr/local/mysql/bin/mysqld_safe
mysqladmin = /usr/local/mysql/bin/mysqladmin
user       = multi_admin
password   = my_password

[mysqld2]
socket     = /tmp/mysql.sock2
port       = 3307
pid-file   = /usr/local/mysql/data2/hostname.pid2
datadir    = /usr/local/mysql/data2
language   = /usr/local/mysql/share/mysql/english
user       = unix_user1

[mysqld3]
mysqld     = /path/to/mysqld_safe
ledir      = /path/to/mysqld-binary/
mysqladmin = /path/to/mysqladmin
socket     = /tmp/mysql.sock3
port       = 3308
pid-file   = /usr/local/mysql/data3/hostname.pid3
datadir    = /usr/local/mysql/data3
language   = /usr/local/mysql/share/mysql/swedish
user       = unix_user2

[mysqld4]
socket     = /tmp/mysql.sock4
port       = 3309
pid-file   = /usr/local/mysql/data4/hostname.pid4
datadir    = /usr/local/mysql/data4
language   = /usr/local/mysql/share/mysql/estonia
user       = unix_user3

[mysqld6]
socket     = /tmp/mysql.sock6
port       = 3311
pid-file   = /usr/local/mysql/data6/hostname.pid6
datadir    = /usr/local/mysql/data6
language   = /usr/local/mysql/share/mysql/japanese
user       = unix_user4

参见 第 6.2.2.2 节，“使用选项文件”。See Section 6.2.2.2, “Using Option Files”.