5.1.7 Server Command Options

Options that affect security: See Section 6.1.4, “Security-Related mysqld Options and Variables”.

SSL-related options: See Section 6.4.2, “Command Options for Encrypted Connections”.

Binary log control options: See Section 5.4.4, “The Binary Log”.

Replication-related options: See Section 17.1.6, “Replication and Binary Logging Options and Variables”.

Options for loading plugins such as pluggable storage engines: See Section 5.6.1, “Installing and Uninstalling Plugins”.

Options specific to particular storage engines: See Section 15.13, “InnoDB Startup Options and System Variables” and Section 16.2.1, “MyISAM Startup Options”.

--help, -?

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

--allow-suspicious-udfs

This option controls whether user-defined functions that have only an xxx symbol for the main function can be loaded. By default, the option is off and only UDFs 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 UDFs. See Section 29.4.2.6, “UDF 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. See Section 1.8, “MySQL Standards Compliance”, and Section 5.1.11, “Server SQL Modes”.

--basedir=dir_name, -b dir_name

The path to the MySQL installation directory. This option sets the basedir 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 default basedir value. This in turn enables the server to use that basedir when searching for server-related information such as the share directory containing error messages.

--big-tables

Enable large result sets by saving all temporary sets in files. This option prevents most “table full” errors, but also slows down queries for which in-memory tables would suffice. The server is able to handle large result sets automatically by using memory for small temporary tables and switching to disk tables where necessary.

--bind-address=addr

The MySQL server listens on one or more network sockets for TCP/IP connections. Each socket is bound to one address, but it is possible for an address to map onto multiple network interfaces. To specify how the server should listen for TCP/IP connections, use the --bind-address option at server startup:

IP addresses can be specified as IPv4 or IPv6 addresses. For any option value that is a host name, the server resolves the name to an IP address and binds to that address. If a host name resolves to multiple IP addresses, the server uses the first IPv4 address if there are any, or the first IPv6 address otherwise.

The server treats different types of addresses as follows:

If binding to any address fails, the server produces an error and does not start.

Examples:

When --bind-address names a single value (wildcard or non-wildcard), the server listens on a single socket, which for a wildcard address may be bound to multiple network interfaces. When --bind-address names a list of multiple values, the server listens on one socket per value, with each socket bound to a single network interface. The number of sockets is linear with the number of values specified. Depending on operating system connection-acceptance efficiency, long value lists might incur a performance penalty for accepting TCP/IP connections.

If you intend to bind the server to a specific address, be sure that the mysql.user system table contains an account with administrative privileges that you can use to connect to that address. Otherwise, you will not be able to shut down the server. For example, if you bind the server to *, you can connect to it using all existing accounts. But if you bind the server to ::1, it accepts connections only on that address. In that case, first make sure that the 'root'@'::1' account is present in the mysql.user table so you can still connect to the server to shut it down.

The server also permits administrative connections on a dedicated interface. See Section 8.12.4.1, “How MySQL Handles Client Connections”.

--binlog-format={ROW|STATEMENT|MIXED}

Specify whether to use row-based, statement-based, or mixed replication. Statement-based is the default in MySQL 8.0. See Section 17.2.1, “Replication Formats”.

Under some conditions, changing this variable at runtime is not possible, or causes replication to fail. See Section 5.4.4.2, “Setting The Binary Log Format”, for more information.

Setting the binary logging format without enabling binary logging sets the binlog_format global system variable and logs a warning.

--character-sets-dir=dir_name

The directory where character sets are installed. See Section 10.14, “Character Set Configuration”.

--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 makes MySQL behave like MySQL 4.0.

--character-set-filesystem=charset_name

The file system character set. This option sets the character_set_filesystem system variable.

--character-set-server=charset_name, -C charset_name

Use charset_name as the default server character set. See Section 10.14, “Character Set Configuration”. If you use this option to specify a nondefault character set, you should also use --collation-server to specify the collation.

--chroot=dir_name, -r dir_name

Put the mysqld server in a closed environment during startup by using the chroot() system call. This is a recommended security measure. Use of this option somewhat limits LOAD DATA INFILE and SELECT ... INTO OUTFILE.

--collation-server=collation_name

Use collation_name as the default server collation. See Section 10.14, “Character Set Configuration”.

--console

(Windows only.) Cause the default error log destination to be the console. This affects log writers that base their own output destination on the default destination. See Section 5.4.2, “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

Write a core file if mysqld dies. The name and location of the core file is system dependent. On Linux, a core file named core.pid is written to the current working directory of the process, which for mysqld is the data directory. pid represents the process ID of the server process. On macOS, a core file named core.pid is written to the /cores directory. On Solaris, use the coreadm 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 to mysqld_safe. See Section 4.3.2, “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 execute ulimit -c unlimited before starting the server. Consult your system documentation.

To reduce the size of core files, the innodb_buffer_pool_in_core_file option can be disabled to prevent InnoDB buffer pool pages from being written to 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, see Section 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, -h dir_name

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

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

If MySQL is configured with the -DWITH_DEBUG=1 CMake option, you can use this option to get a trace file of what mysqld is doing. A typical debug_options string is d:t:o,file_name. The default is d:t:i:o,/tmp/mysqld.trace on Unix and d: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 to P:T.

For more information, see Section 29.5.3, “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 -DENABLE_DEBUG_SYNC=1 CMake option (see Section 2.9.4, “MySQL Source-Configuration Options”). If Debug Sync is not compiled in, 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, see MySQL Internals: Test Synchronization.

--default-storage-engine=type

Set the default storage engine for tables. See Chapter 16, Alternative Storage Engines. This option sets the storage engine for permanent tables only. To set the storage engine for TEMPORARY tables, set the default_tmp_storage_engine system variable.

If you disable the default storage engine at server startup, you must set the default engine for both permanent and TEMPORARY tables to a different engine or the server will not start.

--default-time-zone=timezone

Set the default server time zone. This option sets the global time_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 the system_time_zone system variable.

--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. file_name is interpreted relative to the current directory if given as a relative path name rather than a full path name. This must be the first option on the command line if it is used.

For additional information about this and other option-file options, see Section 4.2.8, “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. file_name is interpreted relative to the current directory if given as a relative path name rather than a full path name.

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

For additional information about this and other option-file options, see Section 4.2.8, “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 of str. For example, mysqld normally reads the [mysqld] group. If the --defaults-group-suffix=_other option is given, mysqld also reads the [mysqld_other] group.

For additional information about this and other option-file options, see Section 4.2.8, “Command-Line Options that Affect Option-File Handling”.

--delay-key-write[={OFF|ON|ALL}]

Specify how to use delayed key writes. Delayed key writing causes key buffers not to be flushed between writes for MyISAM tables. OFF disables delayed key writes. ON enables delayed key writes for those tables that were created with the DELAY_KEY_WRITE option. ALL delays key writes for all MyISAM tables. See Section 5.1.1, “Configuring the Server”, and Section 16.2.1, “MyISAM Startup Options”.

--des-key-file=file_name

This option was removed in MySQL 8.0.3.

--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. If multiple --early-plugin-load options are given, only the last one is used.

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

For example, if plugins named myplug1 and myplug2 have library files myplug1.so and myplug2.so, use this option to perform an early plugin load:

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

Quotes are used around the argument value because otherwise a semicolon (;) is interpreted as a special character by some command interpreters. (Unix shells treat it as a command terminator, for example.)

Each named plugin is loaded early for a single invocation of mysqld 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.

The default --early-plugin-load value is empty. To load the keyring_file plugin, you must use an explicit --early-plugin-load option with a nonempty value.

The InnoDB tablespace encryption feature relies on the keyring_file plugin for encryption key management, and the keyring_file plugin must be loaded prior to storage engine initialization to facilitate InnoDB recovery for encrypted tables. Administrators who want the keyring_file plugin loaded at startup should use the appropriate nonempty option value; for example, keyring_file.so on Unix and Unix-like systems and keyring_file.dll on Windows.

For information about InnoDB tablespace encryption, see Section 15.6.3.9, “Tablespace Encryption”. For general information about plugin loading, see Section 5.6.1, “Installing and Uninstalling Plugins”.

--enable-named-pipe

Enable support for named pipes. This option applies only on Windows.

--event-scheduler[=value]

Enable or disable, and start or stop, the event scheduler.

For detailed information, see The --event-scheduler Option.

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

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

--external-locking

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

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

External locking affects only MyISAM table access. For more information, including conditions under which it can and cannot be used, see Section 8.11.5, “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. See Section B.5.3.3, “What to Do If MySQL Keeps Crashing”.

--gdb

Install an interrupt handler for SIGINT (needed to stop mysqld with ^C to set breakpoints) and disable stack tracing and core file handling. See Section 29.5, “Debugging and Porting MySQL”.

On Windows, this option also suppresses the forking that is used to implement the RESTART 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.

--general-log[={0|1}]

Specify the initial general query log state. With no argument or an argument of 1, the --general-log option enables the log. If omitted or given with an argument of 0, the option disables the log.

--initialize, -I

This option is used to initialize a MySQL installation by creating the data directory and populating the tables in the mysql system database. For more information, see Section 2.10.1.1, “Initializing the Data Directory Manually Using mysqld”.

When the server is started with --initialize, some functionality is unavailable that limits the statements permitted in any file named by the --init-file option. For more information, see the description of that option. In addition, the disabled_storage_engines system variable has no effect.

The --ndbcluster option is ignored when used together with --initialize.

--initialize is mutually exclusive with --daemonize.

-I is a synonym for --initialize.

--initialize-insecure

This option is used to initialize a MySQL installation by creating the data directory and populating the tables in the mysql system database. This option implies --initialize. For more information, see the description of that option, and Section 2.10.1.1, “Initializing the Data Directory Manually Using mysqld”.

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

--init-file=file_name

Read SQL statements from this file at startup. Each statement must be on a single line and should not include comments.

If the server is started with the --initialize or --initialize-insecure option, it operates in bootstap mode and some functionality is unavailable that limits the statements permitted in the file. These include statements that relate to account management (such as CREATE USER or GRANT), replication, and global transaction identifiers. See Section 17.1.3, “Replication with Global Transaction Identifiers”.

--innodb-xxx

Set an option for the InnoDB storage engine. The InnoDB options are listed in Section 15.13, “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 is MySQL if no service_name value is given. For more information, see Section 2.3.5.8, “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 is MySQL if no service_name value is given. For more information, see Section 2.3.5.8, “Starting MySQL as a Windows Service”.

--language=lang_name, -L lang_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. See Section 10.11, “Setting the Error Message Language”.

--lc-messages-dir and --lc-messages should be used rather than --language, which is deprecated (and handled as an alias for --lc-messages-dir). The --language option will 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). See Section 8.12.3.2, “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 is en_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. See Section 10.11, “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. See Section 10.11, “Setting the Error Message Language”.

--local-service

(Windows only) A --local-service option following the service name causes the server to run using the LocalService 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. See Section 2.3.5.8, “Starting MySQL as a Windows Service”.

--log-error[=file_name]

Set the default error log destination to the named file. This affects log writers that base their own output destination on the default destination. See Section 5.4.2, “The Error Log”.

If the option names no file, the default error log destination on Unix and Unix-like systems is a file named host_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 all MyISAM changes to this file (used only when debugging MyISAM).

--log-queries-not-using-indexes

If you are using this option with the slow query log enabled, queries that are expected to retrieve all rows are logged. See Section 5.4.5, “The Slow Query Log”. This option does not necessarily mean that no index is used. For example, a query that uses a full index scan uses an index but would be logged because the index would not limit the number of rows.

--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, see Section 6.1.2.3, “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 is tc.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.

--log-warnings[=level], -W [level]

This option was removed in MySQL 8.0.3. Use the log_error_verbosity system variable instead.

--low-priority-updates

Give table-modifying operations (INSERT, REPLACE, DELETE, UPDATE) lower priority than selects. This can also be done using {INSERT | REPLACE | DELETE | UPDATE} LOW_PRIORITY ... to lower the priority of only one query, or by SET LOW_PRIORITY_UPDATES=1 to change the priority in one thread. This affects only storage engines that use only table-level locking (MyISAM, MEMORY, MERGE). See Section 8.11.2, “Table Locking Issues”.

--min-examined-row-limit=number

When this option is set, queries which examine fewer than number rows are not written to the slow query log. The default is 0.

--memlock

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

--memlock works on systems that support the mlockall() 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 not mlockall() (and thus this option) is supported by checking to see whether or not it is defined in the system mman.h file, like this:

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

If mlockall() 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 for MyISAM index pages.

--myisam-recover-options[=option[,option]...]]

Set the MyISAM storage engine recovery mode. The option value is any combination of the values of OFF, DEFAULT, BACKUP, FORCE, or QUICK. If you specify multiple values, separate them by commas. Specifying the option with no argument is the same as specifying DEFAULT, and specifying with an explicit value of "" disables recovery (same as a value of OFF). If recovery is enabled, each time mysqld opens a MyISAM table, it checks whether the table is marked as crashed or was not closed properly. (The last option works only if you are running with external locking disabled.) If this is the case, mysqld runs a check on the table. If the table was corrupted, mysqld attempts to repair it.

The following options affect how the repair works.

Before the server automatically repairs a table, it writes a note about the repair to the error log. If you want to be able to recover from most problems without user intervention, you should use the options BACKUP,FORCE. This forces a repair of a table even if some rows would be deleted, but it keeps the old data file as a backup so that you can later examine what happened.

See Section 16.2.1, “MyISAM Startup Options”.

--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, see Section 4.2.8, “Command-Line Options that Affect Option-File Handling”.

--no-dd-upgrade

Prevents the automatic upgrade of data dictionary tables when starting the MySQL server. This option would typically be used when starting the MySQL server following an in-place upgrade of the MySQL server to a new version, which may include changes to data dictionary table definitions.

When --no-dd-upgrade is specified, and the server finds that the data dictionary version of the server is different from the version stored in the data dictionary, startup fails with an error stating that data dictionary upgrade is prohibited.

During a normal startup, the data dictionary version of the server is compared to the version stored in the data dictionary to determine if 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 the RESTART 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-alter-table

When this option is given, the server does not use the optimized method of processing an ALTER TABLE operation. It reverts to using a temporary table, copying over the data, and then renaming the temporary table to the original, as used by MySQL 5.0 and earlier. For more information on the operation of ALTER TABLE, see Section 13.1.9, “ALTER TABLE Syntax”.

--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 the user table.) See Section 6.3.6, “Setting Account Resource Limits”.

--open-files-limit=count

Changes the number of file descriptors available to mysqld. You should try increasing the value of this option if mysqld gives you the error Too many open files. mysqld uses the option value to reserve descriptors with setrlimit(). Internally, the maximum value for this option is the maximum unsigned integer value, but the actual maximum is platform dependent. If the requested number of file descriptors cannot be allocated, mysqld writes a warning to the error log.

mysqld may attempt to allocate more than the requested number of descriptors (if they are available), using the values of max_connections and table_open_cache to estimate whether more descriptors will be needed.

On Unix, the value cannot be set greater than ulimit -n.

--performance-schema-xxx

Configure a Performance Schema option. For details, see Section 26.14, “Performance Schema Command Options”.

--pid-file=file_name

The path name of the process ID file. The server creates the file in the data directory unless an absolute path name is given to specify a different directory. If you specify this option, you must specify a value. If you do not specify this option, MySQL uses a default value of host_name.pid, where host_name is the name of the host machine.

The process ID file is used by other programs such as mysqld_safe to determine the server's process ID. On Windows, this variable also affects the default error log file name. See Section 5.4.2, “The Error Log”.

--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 for InnoDB 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 (see Section 4.2.6, “Program Option Modifiers”). For example, --skip-plugin-innodb_file_per_table disables innodb_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.

--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 is used. Additional plugins to load may be specified using --plugin-load-add options.

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

For example, if plugins named myplug1 and myplug2 have library files myplug1.so and myplug2.so, use this option to perform an early plugin load:

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

Quotes are used around the argument value here because otherwise semicolon (;) is interpreted as a special character by some command interpreters. (Unix shells treat it as a command terminator, for example.)

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

Under normal startup, the server determines which plugins to load by reading the mysql.plugins system table. If the server is started with the --skip-grant-tables option, it does not consult the mysql.plugins table and does not load plugins listed there. --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.

For additional information about plugin loading, see Section 5.6.1, “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

For additional information about plugin loading, see Section 5.6.1, “Installing and Uninstalling Plugins”.

--port=port_num, -P port_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 the root 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, see Section 4.2.8, “Command-Line Options that Affect Option-File Handling”.

--remove [service_name]

(Windows only) Remove a MySQL Windows service. The default service name is MySQL if no service_name value is given. For more information, see Section 2.3.5.8, “Starting MySQL as a Windows Service”.

--safe-user-create

If this option is enabled, a user cannot create new MySQL users by using the GRANT statement unless the user has the INSERT privilege for the mysql.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:

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

--secure-auth

This option was removed in MySQL 8.0.3.

--secure-file-priv=dir_name

This option sets the secure_file_priv system variable, which is used to limit the effect of data import and export operations, such as those performed by the LOAD DATA and SELECT ... INTO OUTFILE statements and the LOAD_FILE() function. For more information, see the description of secure_file_priv.

--shared-memory

Enable shared-memory connections by local clients. This option is available only on Windows.

--shared-memory-base-name=name

The name of shared memory to use for shared-memory connections. This option is available only on Windows. The default name is MYSQL. The name is case sensitive.

--skip-concurrent-insert

Turn off the ability to select and insert at the same time on MyISAM tables. (This is to be used only if you think you have found a bug in this feature.) See Section 8.11.3, “Concurrent Inserts”.

--skip-event-scheduler

Turns the Event Scheduler OFF. This is not the same as disabling the Event Scheduler, which requires setting --event-scheduler=DISABLED; see The --event-scheduler Option, for more information.

--skip-grant-tables

This option causes the server to start without using the privilege system at all, which gives anyone with access to the server unrestricted access to all databases. You can cause a running server to start using the grant tables again by executing mysqladmin flush-privileges or mysqladmin reload command from a system shell, or by issuing a MySQL FLUSH PRIVILEGES statement after connecting to the server.

If the server is started with the --skip-grant-tables option to disable authentication checks, the server enables --skip-networking automatically to prevent remote connections.

This option also causes the server to suppress during its startup sequence the loading of user-defined functions (UDFs), scheduled events, and plugins that were installed with the INSTALL PLUGIN statement. To cause plugins to be loaded anyway, use the --plugin-load option. --skip-grant-tables also causes the disabled_storage_engines system variable to have no effect.

This option does not cause loading of server components to be suppressed during server startup.

FLUSH PRIVILEGES might be executed implicitly by other actions performed after startup. For example, mysql_upgrade flushes the privileges during the upgrade procedure.

--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 the host_cache_size system variable to 0, but host_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.

If you start the server with --skip-host-cache, that does not prevent changes to the value of host_cache_size, but such changes have no effect and the cache is not re-enabled even if host_cache_size is set larger than 0.

For more information about how the host cache works, see Section 8.12.4.2, “DNS Lookup Optimization and the Host Cache”.

--skip-innodb

Disable the InnoDB storage engine. In this case, because the default storage engine is InnoDB, the server will 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 and TEMPORARY tables.

The InnoDB storage engine cannot be disabled, and the --skip-innodb option is deprecated and has no effect. Its use results in a warning. This option will be removed in a future MySQL release.

--skip-name-resolve

Do not resolve host names when checking client connections. Use only IP addresses. If you use this option, all Host column values in the grant tables must be IP addresses. See Section 8.12.4.2, “DNS Lookup Optimization and the Host Cache”.

Depending on the network configuration of your system and the Host values for your accounts, clients may need to connect using an explicit --host option, such as --host=127.0.0.1 or --host=::1.

An attempt to connect to the host 127.0.0.1 normally resolves to the localhost account. However, this fails if the server is run with the --skip-name-resolve option. If you plan to do that, make sure that an account exists that can accept a connection. For example, to be able to connect as root using --host=127.0.0.1 or --host=::1, create these accounts:

--skip-networking

Do not listen for TCP/IP connections at all. All interaction with mysqld must be made using named pipes or shared memory (on Windows) or Unix socket files (on Unix). This option is highly recommended for systems where only local clients are permitted. See Section 8.12.4.2, “DNS Lookup Optimization and the Host Cache”.

If the server is started with the --skip-grant-tables option to disable authentication checks, the server enables --skip-networking to prevent remote connections.

--ssl*

Options that begin with --ssl specify whether to permit clients to connect using SSL and indicate where to find SSL keys and certificates. See Section 6.4.2, “Command Options for Encrypted Connections”.

--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 a MyISAM index file or data file to another directory with the INDEX DIRECTORY or DATA DIRECTORY option of the CREATE TABLE statement. If you delete or rename the table, the files that its symbolic links point to also are deleted or renamed. See Section 8.12.2.2, “Using Symbolic Links for MyISAM Tables on Unix”.

This option has no meaning on Windows.

--skip-show-database

This option sets the skip_show_database system variable that controls who is permitted to use the SHOW DATABASES statement. See Section 5.1.8, “Server System Variables”.

--skip-stack-trace

Do not write stack traces. This option is useful when you are running mysqld under a debugger. On some systems, you also must use this option to get a core file. See Section 29.5, “Debugging and Porting MySQL”.

--slow-query-log[={0|1}]

Specify the initial slow query log state. With no argument or an argument of 1, the --slow-query-log option enables the log. If omitted or given with an argument of 0, the option disables the log.

--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 is MySQL (not case sensitive).

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

Set the SQL mode. See Section 5.1.11, “Server SQL Modes”.

--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 of NOW(). This option causes SYSDATE() to be an alias for NOW(). For information about the implications for binary logging and replication, see the description for SYSDATE() in Section 12.7, “Date and Time Functions” and for SET TIMESTAMP in Section 5.1.8, “Server System Variables”.

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

The type of decision to use in the heuristic recovery process. To use this option, two or more storage engines that support XA transactions must be installed.

--temp-pool

This option is obsolete and was removed in MySQL 8.0.1.

--transaction-isolation=level

Sets the default transaction isolation level. The level value can be READ-UNCOMMITTED, READ-COMMITTED, REPEATABLE-READ, or SERIALIZABLE. See Section 13.3.7, “SET TRANSACTION Syntax”.

The default transaction isolation level can also be set at runtime using the SET TRANSACTION statement or by setting the transaction_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 the SET TRANSACTION statement or set the transaction_read_only system variable. See Section 13.3.7, “SET TRANSACTION Syntax”.

--tmpdir=dir_name, -t dir_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. If the MySQL server is acting as a replication slave, you should not set --tmpdir to point to a directory on a memory-based file system or to a directory that is cleared when the server host restarts. For more information about the storage location of temporary files, see Section B.5.3.5, “Where MySQL Stores Temporary Files”. A replication slave needs some of its temporary files to survive a machine restart so that it can replicate temporary tables or LOAD DATA INFILE operations. If files in the temporary file directory are lost when the server restarts, replication fails.

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

Run the mysqld server as the user having the name user_name or the numeric user ID user_id. (“User” in this context refers to a system login account, not a MySQL user listed in the grant tables.)

This option is mandatory when starting mysqld as root. The server changes its user ID during its startup sequence, causing it to run as that particular user rather than as root. See Section 6.1.1, “Security Guidelines”.

To avoid a possible security hole where a user adds a --user=root option to a my.cnf file (thus causing the server to run as root), 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 than root. The option in /etc/my.cnf is found before any other --user options, which ensures that the server runs as a user other than root, 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. Warnings and information messages may also be displayed, depending on the log_error_verbosity value, but do not produce immediate validation termination or an exit code of 1. For more information, see Section 5.1.3, “Server Configuration Validation”.

--verbose, -v

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

--version, -V

Display version information and exit.