Movatterモバイル変換

Options that affect security: SeeSection 8.1.4, “Security-Related mysqld Options and Variables”.

SSL-related options: SeeCommand Options for Encrypted Connections.

Binary log control options: SeeSection 7.4.4, “The Binary Log”.

Replication-related options: SeeSection 19.1.6, “Replication and Binary Logging Options and Variables”.

Options for loading plugins such as pluggable storage engines: SeeSection 7.6.1, “Installing and Uninstalling Plugins”.

Options specific to particular storage engines: SeeSection 17.14, “InnoDB Startup Options and System Variables” andSection 18.2.1, “MyISAM Startup Options”.

--help,-?

Display a short help message and exit. Use both the--verbose and--help options to see the full message.

--admin-ssl,--skip-admin-ssl

The--admin-ssl option is like the--ssl option, except that it applies to the administrative connection interface rather than the main connection interface. For information about these interfaces, seeSection 7.1.12.1, “Connection Interfaces”.

The--admin-ssl option specifies that the server permits but does not require encrypted connections on the administrative interface. This option is enabled by default.

--admin-ssl can be specified in negated form as--skip-admin-ssl or a synonym (--admin-ssl=OFF,--disable-admin-ssl). In this case, the option specifies that the server doesnot permit encrypted connections, regardless of the settings of theadmin_tsl_xxx andadmin_ssl_xxx system variables.

The--admin-ssl option has an effect only at server startup on whether the administrative interface supports encrypted connections. It is ignored and has no effect on the operation ofALTER INSTANCE RELOAD TLS at runtime. For example, you can use--admin-ssl=OFF to start the administrative interface with encrypted connections disabled, then reconfigure TLS and executeALTER INSTANCE RELOAD TLS FOR CHANNEL mysql_admin to enable encrypted connections at runtime.

For general information about configuring connection-encryption support, seeSection 8.3.1, “Configuring MySQL to Use Encrypted Connections”. That discussion is written for the main connection interface, but the parameter names are similar for the administrative connection interface. Consider setting at least theadmin_ssl_cert andadmin_ssl_key system variables on the server side and the--ssl-ca (or--ssl-capath) option on the client side. For additional information specifically about the administrative interface, seeAdministrative Interface Support for Encrypted Connections.

Because support for encrypted connections is enabled by default, it is normally unnecessary to specify--admin-ssl. As of MySQL 8.0.26,--admin-ssl is deprecated and subject to removal in a future MySQL version. If it is desired to disable encrypted connections, that can be done without specifying--admin-ssl in negated form. Set theadmin_tls_version system variable to the empty value to indicate that no TLS versions are supported. For example, these lines in the servermy.cnf file disable encrypted connections:

[mysqld]admin_tls_version=''

--allow-suspicious-udfs

This option controls whether loadable functions that have only anxxx symbol for the main function can be loaded. By default, the option is off and only loadable functions that have at least one auxiliary symbol can be loaded; this prevents attempts at loading functions from shared object files other than those containing legitimate functions. SeeLoadable Function Security Precautions.

--ansi

Use standard (ANSI) SQL syntax instead of MySQL syntax. For more precise control over the server SQL mode, use the--sql-mode option instead. SeeSection 1.6, “MySQL Standards Compliance”, andSection 7.1.11, “Server SQL Modes”.

--basedir=dir_name,-bdir_name

The path to the MySQL installation directory. This option sets thebasedir system variable.

The server executable determines its own full path name at startup and uses the parent of the directory in which it is located as the defaultbasedir value. This in turn enables the server to use thatbasedir when searching for server-related information such as theshare directory containing error messages.

--character-set-client-handshake

Do not ignore character set information sent by the client. To ignore client information and use the default server character set, use--skip-character-set-client-handshake.

This option is deprecated in MySQL 8.0.35 and later MySQL 8.0 releases, where a warning is issued whenever it is used, and is to be removed in a future version of MySQL. Applications which depen on this option should begin migration away from it as soon as possible.

--check-table-functions=value

When performing an upgade of the server, we scan the data dictionary for functions used in table constraints and other expressions, includingDEFAULT expressions, partitioning expressions, and virtual columns. It is possible that a change in the behavior of the function causes it to raise an error in the new version of the server, where no such error occurred before in which case the table cannot be opened. This option provides a choice in how to handle such problems, according to which of the two values shown here is used:

The default behaviour is to abort the upgrade, so that the user can fix the issue using the older version of the server, before upgrading to the newer one. UseWARN to continue the upgrade in interactive mode while reporting any issues.

The--check-table-functions option was introduced in MySQL 8.0.42.

--chroot=dir_name,-rdir_name

Put themysqld server in a closed environment during startup by using thechroot() system call. This is a recommended security measure. Use of this option somewhat limitsLOAD DATA andSELECT ... INTO OUTFILE.

--console

(Windows only.) Cause the default error log destination to be the console. This affects log sinks that base their own output destination on the default destination. SeeSection 7.4.2, “The Error Log”.mysqld does not close the console window if this option is used.

--console takes precedence over--log-error if both are given.

--core-file

When this option is used, write a core file ifmysqld dies; no arguments are needed (or accepted). The name and location of the core file is system dependent. On Linux, a core file namedcore.pid is written to the current working directory of the process, which formysqld is the data directory.pid represents the process ID of the server process. On macOS, a core file namedcore.pid is written to the/cores directory. On Solaris, use thecoreadm command to specify where to write the core file and how to name it.

For some systems, to get a core file you must also specify the--core-file-size option tomysqld_safe. SeeSection 6.3.2, “mysqld_safe — MySQL Server Startup Script”. On some systems, such as Solaris, you do not get a core file if you are also using the--user option. There might be additional restrictions or limitations. For example, it might be necessary to executeulimit -c unlimited before starting the server. Consult your system documentation.

Theinnodb_buffer_pool_in_core_file variable can be used to reduce the size of core files on operating systems that support it. For more information, seeSection 17.8.3.7, “Excluding Buffer Pool Pages from Core Files”.

--daemonize,-D

This option causes the server to run as a traditional, forking daemon, permitting it to work with operating systems that use systemd for process control. For more information, seeSection 2.5.9, “Managing MySQL Server with systemd”.

--daemonize is mutually exclusive with--initialize and--initialize-insecure.

If the server is started using the--daemonize option and is not connected to a tty device, a default error logging option of--log-error="" is used in the absence of an explicit logging option, to direct error output to the default log file.

-D is a synonym for--daemonize.

--datadir=dir_name,-hdir_name

The path to the MySQL server data directory. This option sets thedatadir system variable. See the description of that variable.

--debug[=debug_options],-# [debug_options]

If MySQL is configured with the-DWITH_DEBUG=1CMake option, you can use this option to get a trace file of whatmysqld is doing. A typicaldebug_options string isd:t:o,file_name. The default isd:t:i:o,/tmp/mysqld.trace on Unix andd:t:i:O,\mysqld.trace on Windows.

Using-DWITH_DEBUG=1 to configure MySQL with debugging support enables you to use the--debug="d,parser_debug" option when you start the server. This causes the Bison parser that is used to process SQL statements to dump a parser trace to the server's standard error output. Typically, this output is written to the error log.

This option may be given multiple times. Values that begin with+ or- are added to or subtracted from the previous value. For example,--debug=T--debug=+P sets the value toP:T.

For more information, seeSection 7.9.4, “The DBUG Package”.

--debug-sync-timeout[=N]

Controls whether the Debug Sync facility for testing and debugging is enabled. Use of Debug Sync requires that MySQL be configured with the-DWITH_DEBUG=ONCMake option (seeSection 2.8.7, “MySQL Source-Configuration Options”); otherwise, this option is not available. The option value is a timeout in seconds. The default value is 0, which disables Debug Sync. To enable it, specify a value greater than 0; this value also becomes the default timeout for individual synchronization points. If the option is given without a value, the timeout is set to 300 seconds.

For a description of the Debug Sync facility and how to use synchronization points, seeMySQL Internals: Test Synchronization.

--default-time-zone=timezone

Set the default server time zone. This option sets the globaltime_zone system variable. If this option is not given, the default time zone is the same as the system time zone (given by the value of thesystem_time_zone system variable.

Thesystem_time_zone variable differs fromtime_zone. Although they might have the same value, the latter variable is used to initialize the time zone for each client that connects. SeeSection 7.1.15, “MySQL Server Time Zone Support”.

--defaults-extra-file=file_name

Read this option file after the global option file but (on Unix) before the user option file. If the file does not exist or is otherwise inaccessible, an error occurs. Iffile_name is not an absolute path name, it is interpreted relative to the current directory. This must be the first option on the command line if it is used.

For additional information about this and other option-file options, seeSection 6.2.2.3, “Command-Line Options that Affect Option-File Handling”.

--defaults-file=file_name

Read only the given option file. If the file does not exist or is otherwise inaccessible, an error occurs. Iffile_name is not an absolute path name, it is interpreted relative to the current directory.

Exception: Even with--defaults-file,mysqld readsmysqld-auto.cnf.

For additional information about this and other option-file options, seeSection 6.2.2.3, “Command-Line Options that Affect Option-File Handling”.

--defaults-group-suffix=str

Read not only the usual option groups, but also groups with the usual names and a suffix ofstr. For example,mysqld normally reads the[mysqld] group. If this option is given as--defaults-group-suffix=_other,mysqld also reads the[mysqld_other] group.

For additional information about this and other option-file options, seeSection 6.2.2.3, “Command-Line Options that Affect Option-File Handling”.

--early-plugin-load=plugin_list

This option tells the server which plugins to load before loading mandatory built-in plugins and before storage engine initialization. Early loading is supported only for plugins compiled withPLUGIN_OPT_ALLOW_EARLY. If multiple--early-plugin-load options are given, only the last one applies.

The option value is a semicolon-separated list ofplugin_library andname=plugin_library values. Eachplugin_library is the name of a library file that contains plugin code, and eachname is the name of a plugin to load. If a plugin library is named without any preceding plugin name, the server loads all plugins in the library. With a preceding plugin name, the server loads only the named plugin from the library. The server looks for plugin library files in the directory named by theplugin_dir system variable.

For example, if plugins namedmyplug1 andmyplug2 are contained in the plugin library filesmyplug1.so andmyplug2.so, use this option to perform an early plugin load:

mysqld --early-plugin-load="myplug1=myplug1.so;myplug2=myplug2.so"

Quotes surround the argument value because otherwise some command interpreters interpret semicolon (;) as a special character. (For example, Unix shells treat it as a command terminator.)

Each named plugin is loaded early for a single invocation ofmysqld only. After a restart, the plugin is not loaded early unless--early-plugin-load is used again.

If the server is started using--initialize or--initialize-insecure, plugins specified by--early-plugin-load are not loaded.

If the server is run with--help, plugins specified by--early-plugin-load are loaded but not initialized. This behavior ensures that plugin options are displayed in the help message.

InnoDB tablespace encryption relies on the MySQL Keyring for encryption key management, and the keyring plugin to be used must be loaded prior to storage engine initialization to facilitateInnoDB recovery for encrypted tables. For example, administrators who want thekeyring_file plugin loaded at startup should use--early-plugin-load with the appropriate option value (such askeyring_file.so on Unix and Unix-like systems orkeyring_file.dll on Windows).

For information aboutInnoDB tablespace encryption, seeSection 17.13, “InnoDB Data-at-Rest Encryption”. For general information about plugin loading, seeSection 7.6.1, “Installing and Uninstalling Plugins”.

--exit-info[=flags],-T [flags]

This is a bitmask of different flags that you can use for debugging themysqld server. Do not use this option unless you knowexactly what it does!

--external-locking

Enable external locking (system locking), which is disabled by default. If you use this option on a system on whichlockd does not fully work (such as Linux), it is easy formysqld to deadlock.

To disable external locking explicitly, use--skip-external-locking.

External locking affects onlyMyISAM table access. For more information, including conditions under which it can and cannot be used, seeSection 10.11.5, “External Locking”.

--flush

Flush (synchronize) all changes to disk after each SQL statement. Normally, MySQL does a write of all changes to disk only after each SQL statement and lets the operating system handle the synchronizing to disk. SeeSection B.3.3.3, “What to Do If MySQL Keeps Crashing”.

--gdb

Install an interrupt handler forSIGINT (needed to stopmysqld with^C to set breakpoints) and disable stack tracing and core file handling. SeeSection 7.9.1.4, “Debugging mysqld under gdb”.

On Windows, this option also suppresses the forking that is used to implement theRESTART statement: Forking enables one process to act as a monitor to the other, which acts as the server. However, forking makes determining the server process to attach to for debugging more difficult, so starting the server with--gdb suppresses forking. For a server started with this option,RESTART simply exits and does not restart.

In non-debug settings,--no-monitor may be used to suppress forking the monitor process.

--initialize,-I

This option is used to initialize a MySQL installation by creating the data directory and populating the tables in themysql system schema. For more information, seeSection 2.9.1, “Initializing the Data Directory”.

This option limits the effects of, or is not compatible with, a number of other startup options for the MySQL server. Some of the most common issues of this sort are noted here:

The items in the preceding list also apply when initializing the server using the--initialize-insecure option.

--initialize-insecure

This option is used to initialize a MySQL installation by creating the data directory and populating the tables in themysql system schema. This option implies--initialize, and the same restrictions and limitations apply; for more information, see the description of that option, andSection 2.9.1, “Initializing the Data Directory”.

--innodb-xxx

Set an option for theInnoDB storage engine. TheInnoDB options are listed inSection 17.14, “InnoDB Startup Options and System Variables”.

--install [service_name]

(Windows only) Install the server as a Windows service that starts automatically during Windows startup. The default service name isMySQL if noservice_name value is given. For more information, seeSection 2.3.4.8, “Starting MySQL as a Windows Service”.

--install-manual [service_name]

(Windows only) Install the server as a Windows service that must be started manually. It does not start automatically during Windows startup. The default service name isMySQL if noservice_name value is given. For more information, seeSection 2.3.4.8, “Starting MySQL as a Windows Service”.

--language=lang_name, -Llang_name

The language to use for error messages.lang_name can be given as the language name or as the full path name to the directory where the language files are installed. SeeSection 12.12, “Setting the Error Message Language”.

--lc-messages-dir and--lc-messages should be used rather than--language, which is deprecated (and handled as a synonym for--lc-messages-dir). You should expect the--language option to be removed in a future MySQL release.

--large-pages

Some hardware/operating system architectures support memory pages greater than the default (usually 4KB). The actual implementation of this support depends on the underlying hardware and operating system. Applications that perform a lot of memory accesses may obtain performance improvements by using large pages due to reduced Translation Lookaside Buffer (TLB) misses.

MySQL supports the Linux implementation of large page support (which is called HugeTLB in Linux). SeeSection 10.12.3.3, “Enabling Large Page Support”. For Solaris support of large pages, see the description of the--super-large-pages option.

--large-pages is disabled by default.

--lc-messages=locale_name

The locale to use for error messages. The default isen_US. The server converts the argument to a language name and combines it with the value of--lc-messages-dir to produce the location for the error message file. SeeSection 12.12, “Setting the Error Message Language”.

--lc-messages-dir=dir_name

The directory where error messages are located. The server uses the value together with the value of--lc-messages to produce the location for the error message file. SeeSection 12.12, “Setting the Error Message Language”.

--local-service

(Windows only) A--local-service option following the service name causes the server to run using theLocalService Windows account that has limited system privileges. If both--defaults-file and--local-service are given following the service name, they can be in any order. SeeSection 2.3.4.8, “Starting MySQL as a Windows Service”.

--log-error[=file_name]

Set the default error log destination to the named file. This affects log sinks that base their own output destination on the default destination. SeeSection 7.4.2, “The Error Log”.

If the option names no file, the default error log destination on Unix and Unix-like systems is a file namedhost_name.err in the data directory. The default destination on Windows is the same, unless the--pid-file option is specified. In that case, the file name is the PID file base name with a suffix of.err in the data directory.

If the option names a file, the default destination is that file (with an.err suffix added if the name has no suffix), located under the data directory unless an absolute path name is given to specify a different location.

If error log output cannot be redirected to the error log file, an error occurs and startup fails.

On Windows,--console takes precedence over--log-error if both are given. In this case, the default error log destination is the console rather than a file.

--log-isam[=file_name]

Log allMyISAM changes to this file (used only when debuggingMyISAM).

--log-raw

Passwords in certain statements written to the general query log, slow query log, and binary log are rewritten by the server not to occur literally in plain text. Password rewriting can be suppressed for the general query log by starting the server with the--log-raw option. This option may be useful for diagnostic purposes, to see the exact text of statements as received by the server, but for security reasons is not recommended for production use.

If a query rewrite plugin is installed, the--log-raw option affects statement logging as follows:

For more information, seeSection 8.1.2.3, “Passwords and Logging”.

--log-short-format

Log less information to the slow query log, if it has been activated.

--log-tc=file_name

The name of the memory-mapped transaction coordinator log file (for XA transactions that affect multiple storage engines when the binary log is disabled). The default name istc.log. The file is created under the data directory if not given as a full path name. This option is unused.

--log-tc-size=size

The size in bytes of the memory-mapped transaction coordinator log. The default and minimum values are 6 times the page size, and the value must be a multiple of the page size.

--memlock

Lock themysqld process in memory. This option might help if you have a problem where the operating system is causingmysqld to swap to disk.

--memlock works on systems that support themlockall() system call; this includes Solaris, most Linux distributions that use a 2.4 or higher kernel, and perhaps other Unix systems. On Linux systems, you can tell whether or notmlockall() (and thus this option) is supported by checking to see whether or not it is defined in the systemmman.h file, like this:

$> grep mlockall /usr/include/sys/mman.h

Ifmlockall() is supported, you should see in the output of the previous command something like the following:

extern int mlockall (int __flags) __THROW;

--myisam-block-size=N

The block size to be used forMyISAM index pages.

--no-defaults

Do not read any option files. If program startup fails due to reading unknown options from an option file,--no-defaults can be used to prevent them from being read. This must be the first option on the command line if it is used.

For additional information about this and other option-file options, seeSection 6.2.2.3, “Command-Line Options that Affect Option-File Handling”.

--no-dd-upgrade

Prevent automatic upgrade of the data dictionary tables during the MySQL server startup process. This option is typically used when starting the MySQL server following an in-place upgrade of an existing installation to a newer MySQL version, which may include changes to data dictionary table definitions.

When--no-dd-upgrade is specified, and the server finds that its expected version of the data dictionary differs from the version stored in the data dictionary itself, startup fails with an error stating that data dictionary upgrade is prohibited;

[ERROR] [MY-011091] [Server] Data dictionary upgrade prohibited by thecommand line option '--no_dd_upgrade'.[ERROR] [MY-010020] [Server] Data Dictionary initialization failed.

During a normal startup, the data dictionary version of the server is compared to the version stored in the data dictionary to determine whether data dictionary table definitions should be upgraded. If an upgrade is necessary and supported, the server creates data dictionary tables with updated definitions, copies persisted metadata to the new tables, atomically replaces the old tables with the new ones, and reinitializes the data dictionary. If an upgrade is not necessary, startup continues without updating data dictionary tables.

--no-monitor

(Windows only). This option suppresses the forking that is used to implement theRESTART statement: Forking enables one process to act as a monitor to the other, which acts as the server. For a server started with this option,RESTART simply exits and does not restart.

--no-monitor is not available prior to MySQL 8.0.12. The--gdb option can be used as a workaround.

--old-style-user-limits

Enable old-style user limits. (Before MySQL 5.0.3, account resource limits were counted separately for each host from which a user connected rather than per account row in theuser table.) SeeSection 8.2.21, “Setting Account Resource Limits”.

This option is deprecated, and, as of MySQL 8.0.30, using it on the command line or in an option file causes MySQL to raise a warning. Expect this option to be removed in a future release; you should check your applications now for use of--old-style-user-limits and remove any dependencies they might have on it, before this happens.

--performance-schema-xxx

Configure a Performance Schema option. For details, seeSection 29.14, “Performance Schema Command Options”.

--plugin-load=plugin_list

This option tells the server to load the named plugins at startup. If multiple--plugin-load options are given, only the last one applies. Additional plugins to load may be specified using--plugin-load-add options.

The option value is a semicolon-separated list ofplugin_library andname=plugin_library values. Eachplugin_library is the name of a library file that contains plugin code, and eachname is the name of a plugin to load. If a plugin library is named without any preceding plugin name, the server loads all plugins in the library. With a preceding plugin name, the server loads only the named plugin from the library. The server looks for plugin library files in the directory named by theplugin_dir system variable.

For example, if plugins namedmyplug1 andmyplug2 are contained in the plugin library filesmyplug1.so andmyplug2.so, use this option to perform an early plugin load:

mysqld --plugin-load="myplug1=myplug1.so;myplug2=myplug2.so"

Quotes surround the argument value because otherwise some command interpreters interpret semicolon (;) as a special character. (For example, Unix shells treat it as a command terminator.)

Each named plugin is loaded for a single invocation ofmysqld only. After a restart, the plugin is not loaded unless--plugin-load is used again. This is in contrast toINSTALL PLUGIN, which adds an entry to themysql.plugins table to cause the plugin to be loaded for every normal server startup.

During the normal startup sequence, the server determines which plugins to load by reading themysql.plugins system table. If the server is started with the--skip-grant-tables option, plugins registered in themysql.plugins table are not loaded and are unavailable.--plugin-load enables plugins to be loaded even when--skip-grant-tables is given.--plugin-load also enables plugins to be loaded at startup that cannot be loaded at runtime.

This option does not set a corresponding system variable. The output ofSHOW PLUGINS provides information about loaded plugins. More detailed information can be found in the Information SchemaPLUGINS table. SeeSection 7.6.2, “Obtaining Server Plugin Information”.

For additional information about plugin loading, seeSection 7.6.1, “Installing and Uninstalling Plugins”.

--plugin-load-add=plugin_list

This option complements the--plugin-load option.--plugin-load-add adds a plugin or plugins to the set of plugins to be loaded at startup. The argument format is the same as for--plugin-load.--plugin-load-add can be used to avoid specifying a large set of plugins as a single long unwieldy--plugin-load argument.

--plugin-load-add can be given in the absence of--plugin-load, but any instance of--plugin-load-add that appears before--plugin-load has no effect because--plugin-load resets the set of plugins to load. In other words, these options:

--plugin-load=x --plugin-load-add=y

are equivalent to this option:

--plugin-load="x;y"

But these options:

--plugin-load-add=y --plugin-load=x

are equivalent to this option:

--plugin-load=x

This option does not set a corresponding system variable. The output ofSHOW PLUGINS provides information about loaded plugins. More detailed information can be found in the Information SchemaPLUGINS table. SeeSection 7.6.2, “Obtaining Server Plugin Information”.

For additional information about plugin loading, seeSection 7.6.1, “Installing and Uninstalling Plugins”.

--plugin-xxx

Specifies an option that pertains to a server plugin. For example, many storage engines can be built as plugins, and for such engines, options for them can be specified with a--plugin prefix. Thus, the--innodb-file-per-table option forInnoDB can be specified as--plugin-innodb-file-per-table.

For boolean options that can be enabled or disabled, the--skip prefix and other alternative formats are supported as well (seeSection 6.2.2.4, “Program Option Modifiers”). For example,--skip-plugin-innodb-file-per-table disablesinnodb-file-per-table.

The rationale for the--plugin prefix is that it enables plugin options to be specified unambiguously if there is a name conflict with a built-in server option. For example, were a plugin writer to name a plugin“sql” and implement a“mode” option, the option name might be--sql-mode, which would conflict with the built-in option of the same name. In such cases, references to the conflicting name are resolved in favor of the built-in option. To avoid the ambiguity, users can specify the plugin option as--plugin-sql-mode. Use of the--plugin prefix for plugin options is recommended to avoid any question of ambiguity.

--port=port_num,-Pport_num

The port number to use when listening for TCP/IP connections. On Unix and Unix-like systems, the port number must be 1024 or higher unless the server is started by theroot operating system user. Setting this option to 0 causes the default value to be used.

--port-open-timeout=num

On some systems, when the server is stopped, the TCP/IP port might not become available immediately. If the server is restarted quickly afterward, its attempt to reopen the port can fail. This option indicates how many seconds the server should wait for the TCP/IP port to become free if it cannot be opened. The default is not to wait.

--print-defaults

Print the program name and all options that it gets from option files. Password values are masked. This must be the first option on the command line if it is used, except that it may be used immediately after--defaults-file or--defaults-extra-file.

For additional information about this and other option-file options, seeSection 6.2.2.3, “Command-Line Options that Affect Option-File Handling”.

--remove [service_name]

(Windows only) Remove a MySQL Windows service. The default service name isMySQL if noservice_name value is given. For more information, seeSection 2.3.4.8, “Starting MySQL as a Windows Service”.

--safe-user-create

This option is deprecated, and ignored as of MySQL 8.0.11. For related information, seeServer Changes.

If this option is enabled, a user cannot create new MySQL users by using theGRANT statement unless the user has theINSERT privilege for themysql.user system table or any column in the table. If you want a user to have the ability to create new users that have those privileges that the user has the right to grant, you should grant the user the following privilege:

GRANT INSERT(user) ON mysql.user TO 'user_name'@'host_name';

This ensures that the user cannot change any privilege columns directly, but has to use theGRANT statement to give privileges to other users.

--skip-grant-tables

This option affects the server startup sequence:

--skip-host-cache

Disable use of the internal host cache for faster name-to-IP resolution. With the cache disabled, the server performs a DNS lookup every time a client connects.

Use of--skip-host-cache is similar to setting thehost_cache_size system variable to 0, buthost_cache_size is more flexible because it can also be used to resize, enable, or disable the host cache at runtime, not just at server startup.

Beginning with MySQL 8.0.30, this option is deprecated; you should useSET GLOBAL host_cache_size = 0 instead.

Starting the server with--skip-host-cache does not prevent runtime changes to the value ofhost_cache_size, but such changes have no effect and the cache is not re-enabled even ifhost_cache_size is set larger than 0.

For more information about how the host cache works, seeSection 7.1.12.3, “DNS Lookups and the Host Cache”.

--skip-innodb

Disable theInnoDB storage engine. In this case, because the default storage engine isInnoDB, the server does not start unless you also use--default-storage-engine and--default-tmp-storage-engine to set the default to some other engine for both permanent andTEMPORARY tables.

TheInnoDB storage engine cannot be disabled, and the--skip-innodb option is deprecated and has no effect. Its use results in a warning. Expect this option to be removed in a future MySQL release.

--skip-new

This option disables (what used to be considered) new, possibly unsafe behaviors. It results in these settings:delay_key_write=OFF,concurrent_insert=NEVER,automatic_sp_privileges=OFF. It also causesOPTIMIZE TABLE to be mapped toALTER TABLE for storage engines for whichOPTIMIZE TABLE is not supported.

This option is deprecated as of MySQL 8.0.35, and is subject to removal in a future release.

--skip-show-database

This option sets theskip_show_database system variable that controls who is permitted to use theSHOW DATABASES statement. SeeSection 7.1.8, “Server System Variables”.

--skip-stack-trace

Do not write stack traces. This option is useful when you are runningmysqld under a debugger. On some systems, you also must use this option to get a core file. SeeSection 7.9, “Debugging MySQL”.

--slow-start-timeout=timeout

This option controls the Windows service control manager's service start timeout. The value is the maximum number of milliseconds that the service control manager waits before trying to kill the windows service during startup. The default value is 15000 (15 seconds). If the MySQL service takes too long to start, you may need to increase this value. A value of 0 means there is no timeout.

--socket=path

On Unix, this option specifies the Unix socket file to use when listening for local connections. The default value is/tmp/mysql.sock. If this option is given, the server creates the file in the data directory unless an absolute path name is given to specify a different directory. On Windows, the option specifies the pipe name to use when listening for local connections that use a named pipe. The default value isMySQL (not case-sensitive).

--sql-mode=value[,value[,value...]]

Set the SQL mode. SeeSection 7.1.11, “Server SQL Modes”.

--ssl,--skip-ssl

The--ssl option specifies that the server permits but does not require encrypted connections on the main connection interface. This option is enabled by default.

A similar option,--admin-ssl, is like the--ssl, except that it applies to the administrative connection interface rather than the main connection interface. For information about these interfaces, seeSection 7.1.12.1, “Connection Interfaces”.

--ssl can be specified in negated form as--skip-ssl or a synonym (--ssl=OFF,--disable-ssl). In this case, the option specifies that the server doesnot permit encrypted connections, regardless of the settings of thetls_xxx andssl_xxx system variables.

The--ssl option has an effect only at server startup on whether the server supports encrypted connections. It is ignored and has no effect on the operation ofALTER INSTANCE RELOAD TLS at runtime. For example, you can use--ssl=OFF to start the server with encrypted connections disabled, then reconfigure TLS and executeALTER INSTANCE RELOAD TLS to enable encrypted connections at runtime.

For more information about configuring whether the server permits clients to connect using SSL and indicating where to find SSL keys and certificates, seeSection 8.3.1, “Configuring MySQL to Use Encrypted Connections”, which also describes server capabilities for certificate and key file autogeneration and autodiscovery. Consider setting at least thessl_cert andssl_key system variables on the server side and the--ssl-ca (or--ssl-capath) option on the client side.

Because support for encrypted connections is enabled by default, it is normally unnecessary to specify--ssl. As of MySQL 8.0.26,--ssl is deprecated and subject to removal in a future MySQL version. If it is desired to disable encrypted connections, that can be done without specifying--ssl in negated form. Set thetls_version system variable to the empty value to indicate that no TLS versions are supported. For example, these lines in the servermy.cnf file disable encrypted connections:

[mysqld]tls_version=''

--standalone

Available on Windows only; instructs the MySQL server not to run as a service.

--super-large-pages

Standard use of large pages in MySQL attempts to use the largest size supported, up to 4MB. Under Solaris, a“super large pages” feature enables uses of pages up to 256MB. This feature is available for recent SPARC platforms. It can be enabled or disabled by using the--super-large-pages or--skip-super-large-pages option.

--symbolic-links,--skip-symbolic-links

Enable or disable symbolic link support. On Unix, enabling symbolic links means that you can link aMyISAM index file or data file to another directory with theINDEX DIRECTORY orDATA DIRECTORY option of theCREATE TABLE statement. If you delete or rename the table, the files that its symbolic links point to also are deleted or renamed. SeeSection 10.12.2.2, “Using Symbolic Links for MyISAM Tables on Unix”.

This option has no meaning on Windows.

--sysdate-is-now

SYSDATE() by default returns the time at which it executes, not the time at which the statement in which it occurs begins executing. This differs from the behavior ofNOW(). This option causesSYSDATE() to be a synonym forNOW(). For information about the implications for binary logging and replication, see the description forSYSDATE() inSection 14.7, “Date and Time Functions” and forSET TIMESTAMP inSection 7.1.8, “Server System Variables”.

--tc-heuristic-recover={COMMIT|ROLLBACK}

The decision to use in a manual heuristic recovery.

If a--tc-heuristic-recover option is specified, the server exits regardless of whether manual heuristic recovery is successful.

On systems with more than one storage engine capable of two-phase commit, theROLLBACK option is not safe and causes recovery to halt with the following error:

[ERROR] --tc-heuristic-recover rollbackstrategy is not safe on systems with more than one 2-phase-commit-capablestorage engine. Aborting crash recovery.

--transaction-isolation=level

Sets the default transaction isolation level. Thelevel value can beREAD-UNCOMMITTED,READ-COMMITTED,REPEATABLE-READ, orSERIALIZABLE. SeeSection 15.3.7, “SET TRANSACTION Statement”.

The default transaction isolation level can also be set at runtime using theSET TRANSACTION statement or by setting thetransaction_isolation system variable.

--transaction-read-only

Sets the default transaction access mode. By default, read-only mode is disabled, so the mode is read/write.

To set the default transaction access mode at runtime, use theSET TRANSACTION statement or set thetransaction_read_only system variable. SeeSection 15.3.7, “SET TRANSACTION Statement”.

--tmpdir=dir_name,-tdir_name

The path of the directory to use for creating temporary files. It might be useful if your default/tmp directory resides on a partition that is too small to hold temporary tables. This option accepts several paths that are used in round-robin fashion. Paths should be separated by colon characters (:) on Unix and semicolon characters (;) on Windows.

--tmpdir can be a non-permanent location, such as a directory on a memory-based file system or a directory that is cleared when the server host restarts. If the MySQL server is acting as a replica, and you are using a non-permanent location for--tmpdir, consider setting a different temporary directory for the replica using thereplica_load_tmpdir orslave_load_tmpdir system variable. For a replica, the temporary files used to replicateLOAD DATA statements are stored in this directory, so with a permanent location they can survive machine restarts, although replication can now continue after a restart if the temporary files have been removed.

For more information about the storage location of temporary files, seeSection B.3.3.5, “Where MySQL Stores Temporary Files”.

--upgrade=value

This option controls whether and how the server performs an automatic upgrade at startup. Automatic upgrade involves two steps:

For details about upgrade steps 1 and 2, seeSection 3.4, “What the MySQL Upgrade Process Upgrades”.

These--upgrade option values are permitted:

The following table summarizes the actions taken by the server for each option value.

--user={user_name|user_id},-u {user_name|user_id}

Run themysqld server as the user having the nameuser_name or the numeric user IDuser_id. (“User” in this context refers to a system login account, not a MySQL user listed in the grant tables.)

This option ismandatory when startingmysqld asroot. The server changes its user ID during its startup sequence, causing it to run as that particular user rather than asroot. SeeSection 8.1.1, “Security Guidelines”.

To avoid a possible security hole where a user adds a--user=root option to amy.cnf file (thus causing the server to run asroot),mysqld uses only the first--user option specified and produces a warning if there are multiple--user options. Options in/etc/my.cnf and$MYSQL_HOME/my.cnf are processed before command-line options, so it is recommended that you put a--user option in/etc/my.cnf and specify a value other thanroot. The option in/etc/my.cnf is found before any other--user options, which ensures that the server runs as a user other thanroot, and that a warning results if any other--user option is found.

--validate-config

Validate the server startup configuration. If no errors are found, the server terminates with an exit code of 0. If an error is found, the server displays a diagnostic message and terminates with an exit code of 1. Warning and information messages may also be displayed, depending on thelog_error_verbosity value, but do not produce immediate validation termination or an exit code of 1. For more information, seeSection 7.1.3, “Server Configuration Validation”.

--validate-user-plugins[={OFF|ON}]

If this option is enabled (the default), the server checks each user account and produces a warning if conditions are found that would make the account unusable:

Enabling--validate-user-plugins slows down server initialization andFLUSH PRIVILEGES. If you do not require the additional checking, you can disable this option at startup to avoid the performance decrement.

--verbose,-v

Use this option with the--help option for detailed help.

--version,-V

Display version information and exit.