5.1.6 Server Command Options

When you start the mysqld server, you can specify program options using any of the methods described in Section 4.2.2, “Specifying Program Options”. The most common methods are to provide options in an option file or on the command line. However, in most cases it is desirable to make sure that the server uses the same options each time it runs. The best way to ensure this is to list them in an option file. See Section 4.2.2.2, “Using Option Files”. That section also describes option file format and syntax.

mysqld reads options from the [mysqld] and [server] groups. mysqld_safe reads options from the [mysqld], [server], [mysqld_safe], and [safe_mysqld] groups. mysql.server reads options from the [mysqld] and [mysql.server] groups.

An embedded MySQL server usually reads options from the [server], [embedded], and [xxxxx_SERVER] groups, where xxxxx is the name of the application into which the server is embedded.

mysqld accepts many command options. For a brief summary, execute this command:

mysqld --help

To see the full list, use this command:

mysqld --verbose --help

Some of the items in the list are actually system variables that can be set at server startup. These can be displayed at runtime using the SHOW VARIABLES statement. Some items displayed by the preceding mysqld command do not appear in SHOW VARIABLES output; this is because they are options only and not system variables.

The following list shows some of the most common server options. Additional options are described in other sections:

Options that affect security: See Section 6.1.4, “Security-Related mysqld Options and Variables”.
SSL-related options: See Command Options for Encrypted Connections.
Binary log control options: See Section 5.4.4, “The Binary Log”.
Replication-related options: See Section 16.1.6, “Replication and Binary Logging Options and Variables”.
Options for loading plugins such as pluggable storage engines: See Section 5.5.1, “Installing and Uninstalling Plugins”.
Options specific to particular storage engines: See Section 14.15, “InnoDB Startup Options and System Variables” and Section 15.2.1, “MyISAM Startup Options”.

Some options control the size of buffers or caches. For a given buffer, the server might need to allocate internal data structures. These structures typically are allocated from the total memory allocated to the buffer, and the amount of space required might be platform dependent. This means that when you assign a value to an option that controls a buffer size, the amount of space actually available might differ from the value assigned. In some cases, the amount might be less than the value assigned. It is also possible that the server adjusts a value upward. For example, if you assign a value of 0 to an option for which the minimal value is 1024, the server sets the value to 1024.

Values for buffer sizes, lengths, and stack sizes are given in bytes unless otherwise specified.

Some options take file name values. Unless otherwise specified, the default file location is the data directory if the value is a relative path name. To specify the location explicitly, use an absolute path name. Suppose that the data directory is /var/mysql/data. If a file-valued option is given as a relative path name, it is located under /var/mysql/data. If the value is an absolute path name, its location is as given by the path name.

You can also set the values of server system variables at server startup by using variable names as options. To assign a value to a server system variable, use an option of the form --var_name=value. For example, --sort_buffer_size=384M sets the sort_buffer_size variable to a value of 384MB.

When you assign a value to a variable, MySQL might automatically correct the value to stay within a given range, or adjust the value to the closest permissible value if only certain values are permitted.

To restrict the maximum value to which a system variable can be set at runtime with the SET statement, specify this maximum by using an option of the form --maximum-var_name=value at server startup.

You can change the values of most system variables at runtime with the SET statement. See Section 13.7.4.1, “SET Syntax for Variable Assignment”.

Section 5.1.7, “Server System Variables”, provides a full description for all variables, and additional information for setting them at server startup and runtime. For information on changing system variables, see Section 5.1.1, “Configuring the Server”.

--help, -?
Command-Line Format --help
Display a short help message and exit. Use both the --verbose and --help options to see the full message.
--allow-suspicious-udfs
Command-Line Format --allow-suspicious-udfs[={OFF|ON}]
Type Boolean
Default Value OFF
This option controls whether loadable functions that have only an xxx 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. See Loadable Function Security Precautions.
--ansi
Command-Line Format --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 1.7, “MySQL Standards Compliance”, and Section 5.1.10, “Server SQL Modes”.
--basedir=dir_name, -b dir_name
Command-Line Format --basedir=dir_name
System Variable basedir
Scope Global
Dynamic No
Type Directory name
Default Value configuration-dependent default
The path to the MySQL installation directory. This option sets the basedir system variable.
--bootstrap
Command-Line Format --bootstrap
Deprecated Yes
This option is used by the mysql_install_db program to create the MySQL privilege tables without having to start a full MySQL server.
Note
mysql_install_db is deprecated because its functionality has been integrated into mysqld, the MySQL server. Consequently, the --bootstrap server option that mysql_install_db passes to mysqld is also deprecated. To initialize a MySQL installation, invoke mysqld with the --initialize or --initialize-insecure option. For more information, see Section 2.10.1, “Initializing the Data Directory”. Expect mysql_install_db and the --bootstrap server option to be removed in a future release of MySQL.
--bootstrap is mutually exclusive with --daemonize, --initialize, and --initialize-insecure.
Global transaction identifiers (GTIDs) are not disabled when --bootstrap is used. --bootstrap was used (Bug #20980271). See Section 16.1.3, “Replication with Global Transaction Identifiers”.
When the server operates in bootstap mode, some functionality is unavailable that limits the statements permitted in any file named by the init_file system variable. For more information, see the description of that variable. In addition, the disabled_storage_engines system variable has no effect.
--character-set-client-handshake
Command-Line Format --character-set-client-handshake[={OFF|ON}]
Type Boolean
Default Value ON
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.
--chroot=dir_name, -r dir_name
Command-Line Format --chroot=dir_name
Type Directory 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 and SELECT ... INTO OUTFILE.
--console
Command-Line Format --console
Platform Specific Windows
(Windows only.) Write the error log to stderr and stdout (the console). mysqld does not close the console window if this option is used.
--console takes precedence over --log-error if both are given. (In MySQL 5.5 and 5.6, this is reversed: --log-error takes precedence over --console if both are given.)
--core-file
Command-Line Format --core-file[={OFF|ON}]
Type Boolean
Default Value OFF
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.
--daemonize
Command-Line Format --daemonize[={OFF|ON}]
Type Boolean
Default Value OFF
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 2.5.10, “Managing MySQL Server with systemd”.
--daemonize is mutually exclusive with --bootstrap, --initialize, and --initialize-insecure.
--datadir=dir_name, -h dir_name
Command-Line Format --datadir=dir_name
System Variable datadir
Scope Global
Dynamic No
Type Directory name
The path to the MySQL server data directory. This option sets the datadir system variable. See the description of that variable.

Command-Line Format	`--help`

Command-Line Format	`--allow-suspicious-udfs[={OFF\|ON}]`
Type	Boolean
Default Value	`OFF`

Command-Line Format	`--ansi`

Command-Line Format	`--basedir=dir_name`
System Variable	`basedir`
Scope	Global
Dynamic	No
Type	Directory name
Default Value	`configuration-dependent default`

Command-Line Format	`--bootstrap`
Deprecated	Yes

Command-Line Format	`--character-set-client-handshake[={OFF\|ON}]`
Type	Boolean
Default Value	`ON`

Command-Line Format	`--chroot=dir_name`
Type	Directory name

Command-Line Format	`--console`
Platform Specific	Windows

Command-Line Format	`--core-file[={OFF\|ON}]`
Type	Boolean
Default Value	`OFF`

Command-Line Format	`--daemonize[={OFF\|ON}]`
Type	Boolean
Default Value	`OFF`

Command-Line Format	`--datadir=dir_name`
System Variable	`datadir`
Scope	Global
Dynamic	No
Type	Directory name

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

Command-Line Format	`--debug[=debug_options]`
System Variable	`debug`
Scope	Global, Session
Dynamic	Yes
Type	String
Default Value (Unix)	`d:t:i:o,/tmp/mysqld.trace`
Default Value (Windows)	`d:t:i:O,\mysqld.trace`

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 5.8.3, “The DBUG Package”.

--debug-sync-timeout[=N]
Command-Line Format --debug-sync-timeout[=#]
Type Integer
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 2.9.7, “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-time-zone=timezone
Command-Line Format --default-time-zone=name
Type String
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.
The system_time_zone variable differs from time_zone. Although they might have the same value, the latter variable is used to initialize the time zone for each client that connects. See Section 5.1.13, “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. If file_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, see Section 4.2.2.3, “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. If file_name is not an absolute path name, it is interpreted relative to the current directory.
Note
This must be the first option on the command line if it is used, except that if the server is started with the --defaults-file and --install (or --install-manual) options, --install (or --install-manual) must be first.
For additional information about this and other option-file options, see Section 4.2.2.3, “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 of str. 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, see Section 4.2.2.3, “Command-Line Options that Affect Option-File Handling”.
--des-key-file=file_name
Command-Line Format --des-key-file=file_name
Deprecated Yes
Read the default DES keys from this file. These keys are used by the DES_ENCRYPT() and DES_DECRYPT() functions.
Note
The DES_ENCRYPT() and DES_DECRYPT() functions are deprecated in MySQL 5.7, are removed in MySQL 8.0, and should no longer be used. Consequently, --des-key-file also is deprecated and is removed in MySQL 8.0.
--disable-partition-engine-check
Command-Line Format --disable-partition-engine-check[={OFF|ON}]
Introduced 5.7.17
Deprecated 5.7.17
Type Boolean
Default Value (≥ 5.7.21) ON
Default Value (≥ 5.7.17, ≤ 5.7.20) OFF
Whether to disable the startup check for tables with nonnative partitioning.
As of MySQL 5.7.17, the generic partitioning handler in the MySQL server is deprecated, and is removed in MySQL 8.0, when the storage engine used for a given table is expected to provide its own (“native”) partitioning handler. Currently, only the InnoDB and NDB storage engines do this.
Use of tables with nonnative partitioning results in an ER_WARN_DEPRECATED_SYNTAX warning. In MySQL 5.7.17 through 5.7.20, the server automatically performs a check at startup to identify tables that use nonnative partitioning; for any that are found, the server writes a message to its error log. To disable this check, use the --disable-partition-engine-check option. In MySQL 5.7.21 and later, this check is not performed; in these versions, you must start the server with --disable-partition-engine-check=false, if you wish for the server to check for tables using the generic partitioning handler (Bug #85830, Bug #25846957).
Use of tables with nonnative partitioning results in an ER_WARN_DEPRECATED_SYNTAX warning. Also, the server performs a check at startup to identify tables that use nonnative partitioning; for any found, the server writes a message to its error log. To disable this check, use the --disable-partition-engine-check option.
To prepare for migration to MySQL 8.0, any table with nonnative partitioning should be changed to use an engine that provides native partitioning, or be made nonpartitioned. For example, to change a table to InnoDB, execute this statement:
```
ALTER TABLE table_name ENGINE = INNODB;
```
--early-plugin-load=plugin_list
Command-Line Format --early-plugin-load=plugin_list
Introduced 5.7.11
Type String
Default Value (≥ 5.7.12) empty string
Default Value (5.7.11) keyring_file plugin library file name
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 with PLUGIN_OPT_ALLOW_EARLY. If multiple --early-plugin-load options are given, only the last one applies.
The option value is a semicolon-separated list of plugin_library and name=plugin_library values. Each plugin_library is the name of a library file that contains plugin code, and each name 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 libary. 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 are contained in the plugin library files myplug1.so and myplug2.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 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.
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 facilitate InnoDB recovery for encrypted tables. For example, administrators who want the keyring_file plugin loaded at startup should use --early-plugin-load with the appropriate option value (such as keyring_file.so on Unix and Unix-like systems or keyring_file.dll on Windows).
Important
In MySQL 5.7.11, the default --early-plugin-load value is the name of the keyring_file plugin library file, causing that plugin to be loaded by default. In MySQL 5.7.12 and higher, the default --early-plugin-load value is empty; to load the keyring_file plugin, you must explicitly specify the option with a value naming the keyring_file plugin library file.
This change of default --early-plugin-load value introduces an incompatibility for InnoDB tablespace encryption for upgrades from 5.7.11 to 5.7.12 or higher. Administrators who have encrypted InnoDB tablespaces must take explicit action to ensure continued loading of the keyring plugin: Start the server with an --early-plugin-load option that names the plugin library file. For additional information, see Section 6.4.4.1, “Keyring Plugin Installation”.
For information about InnoDB tablespace encryption, see Section 14.14, “InnoDB Data-at-Rest Encryption”. For general information about plugin loading, see Section 5.5.1, “Installing and Uninstalling Plugins”.
--exit-info[=flags], -T [flags]
Command-Line Format --exit-info[=flags]
Type Integer
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
Command-Line Format --external-locking[={OFF|ON}]
Type Boolean
Default Value OFF
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
Command-Line Format --flush[={OFF|ON}]
System Variable flush
Scope Global
Dynamic Yes
Type Boolean
Default Value OFF
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.3.3.3, “What to Do If MySQL Keeps Crashing”.
Note
If --flush is specified, the value of flush_time does not matter and changes to flush_time have no effect on flush behavior.
--gdb
Command-Line Format --gdb[={OFF|ON}]
Type Boolean
Default Value OFF
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 5.8.1.4, “Debugging mysqld under gdb”.
--ignore-db-dir=dir_name
Command-Line Format --ignore-db-dir=dir_name
Deprecated 5.7.16
Type Directory name
This option tells the server to ignore the given directory name for purposes of the SHOW DATABASES statement or INFORMATION_SCHEMA tables. For example, if a MySQL configuration locates the data directory at the root of a file system on Unix, the system might create a lost+found directory there that the server should ignore. Starting the server with --ignore-db-dir=lost+found causes that name not to be listed as a database.
To specify more than one name, use this option multiple times, once for each name. Specifying the option with an empty value (that is, as --ignore-db-dir=) resets the directory list to the empty list.
Instances of this option given at server startup are used to set the ignore_db_dirs system variable.
This option is deprecated in MySQL 5.7. With the introduction of the data dictionary in MySQL 8.0, it became superfluous and was removed in that version.
--initialize
Command-Line Format --initialize[={OFF|ON}]
Type Boolean
Default Value OFF
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, “Initializing the Data Directory”.
When the server is started with --initialize, some functionality is unavailable that limits the statements permitted in any file named by the init_file system variable. For more information, see the description of that variable. In addition, the disabled_storage_engines system variable has no effect.
In MySQL NDB Cluster 7.5.4 and later, the --ndbcluster option is ignored when used together with --initialize. (Bug #81689, Bug #23518923)
--initialize is mutually exclusive with --bootstrap and --daemonize.
--initialize-insecure
Command-Line Format --initialize-insecure[={OFF|ON}]
Type Boolean
Default Value OFF
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, “Initializing the Data Directory”.
--initialize-insecure is mutually exclusive with --bootstrap and --daemonize.
--innodb-xxx
Set an option for the InnoDB storage engine. The InnoDB options are listed in Section 14.15, “InnoDB Startup Options and System Variables”.
--install [service_name]
Command-Line Format --install [service_name]
Platform Specific Windows
(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 2.3.4.8, “Starting MySQL as a Windows Service”.
Note
If the server is started with the --defaults-file and --install options, --install must be first.
--install-manual [service_name]
Command-Line Format --install-manual [service_name]
Platform Specific Windows
(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 2.3.4.8, “Starting MySQL as a Windows Service”.
Note
If the server is started with the --defaults-file and --install-manual options, --install-manual must be first.

Command-Line Format	`--debug-sync-timeout[=#]`
Type	Integer

Command-Line Format	`--default-time-zone=name`
Type	String

Command-Line Format	`--des-key-file=file_name`
Deprecated	Yes

Command-Line Format	`--disable-partition-engine-check[={OFF\|ON}]`
Introduced	5.7.17
Deprecated	5.7.17
Type	Boolean
Default Value (≥ 5.7.21)	`ON`
Default Value (≥ 5.7.17, ≤ 5.7.20)	`OFF`

Command-Line Format	`--early-plugin-load=plugin_list`
Introduced	5.7.11
Type	String
Default Value (≥ 5.7.12)	`empty string`
Default Value (5.7.11)	`keyring_file plugin library file name`

Command-Line Format	`--exit-info[=flags]`
Type	Integer

Command-Line Format	`--external-locking[={OFF\|ON}]`
Type	Boolean
Default Value	`OFF`

Command-Line Format	`--flush[={OFF\|ON}]`
System Variable	`flush`
Scope	Global
Dynamic	Yes
Type	Boolean
Default Value	`OFF`

Command-Line Format	`--gdb[={OFF\|ON}]`
Type	Boolean
Default Value	`OFF`

Command-Line Format	`--ignore-db-dir=dir_name`
Deprecated	5.7.16
Type	Directory name

Command-Line Format	`--initialize[={OFF\|ON}]`
Type	Boolean
Default Value	`OFF`

Command-Line Format	`--initialize-insecure[={OFF\|ON}]`
Type	Boolean
Default Value	`OFF`

Command-Line Format	`--install [service_name]`
Platform Specific	Windows

Command-Line Format	`--install-manual [service_name]`
Platform Specific	Windows

--language=lang_name, -L lang_name

Command-Line Format	`--language=name`
Deprecated	Yes; use `lc-messages-dir` instead
System Variable	`language`
Scope	Global
Dynamic	No
Type	Directory name
Default Value	`/usr/local/mysql/share/mysql/english/`

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 10.12, “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 release of MySQL.

--large-pages
Command-Line Format --large-pages[={OFF|ON}]
System Variable large_pages
Scope Global
Dynamic No
Platform Specific Linux
Type Boolean
Default Value OFF
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 8.12.4.2, “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
Command-Line Format --lc-messages=name
System Variable lc_messages
Scope Global, Session
Dynamic Yes
Type String
Default Value en_US
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 10.12, “Setting the Error Message Language”.
--lc-messages-dir=dir_name
Command-Line Format --lc-messages-dir=dir_name
System Variable lc_messages_dir
Scope Global
Dynamic No
Type Directory 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 10.12, “Setting the Error Message Language”.
--local-service
Command-Line Format --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 2.3.4.8, “Starting MySQL as a Windows Service”.
--log-error[=file_name]
Command-Line Format --log-error[=file_name]
System Variable log_error
Scope Global
Dynamic No
Type File name
Write the error log and startup messages to this file. See Section 5.4.2, “The Error Log”.
If the option names no file, the error log file name on Unix and Unix-like systems is host_name.err in the data directory. The file name 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 error log file has that name (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.
On Windows, --console takes precedence over --log-error if both are given. In this case, the server writes the error log to the console rather than to a file. (In MySQL 5.5 and 5.6, this is reversed: --log-error takes precedence over --console if both are given.)
--log-isam[=file_name]
Command-Line Format --log-isam[=file_name]
Type File name
Log all MyISAM changes to this file (used only when debugging MyISAM).
--log-raw
Command-Line Format --log-raw[={OFF|ON}]
Type Boolean
Default Value OFF
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:
- Without --log-raw, the server logs the statement returned by the query rewrite plugin. This may differ from the statement as received.
- With --log-raw, the server logs the original statement as received.
For more information, see Section 6.1.2.3, “Passwords and Logging”.
--log-short-format
Command-Line Format --log-short-format[={OFF|ON}]
Type Boolean
Default Value OFF
Log less information to the slow query log, if it has been activated.
--log-tc=file_name
Command-Line Format --log-tc=file_name
Type File name
Default Value tc.log
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.

Command-Line Format	`--large-pages[={OFF\|ON}]`
System Variable	`large_pages`
Scope	Global
Dynamic	No
Platform Specific	Linux
Type	Boolean
Default Value	`OFF`

Command-Line Format	`--lc-messages=name`
System Variable	`lc_messages`
Scope	Global, Session
Dynamic	Yes
Type	String
Default Value	`en_US`

Command-Line Format	`--lc-messages-dir=dir_name`
System Variable	`lc_messages_dir`
Scope	Global
Dynamic	No
Type	Directory name

Command-Line Format	`--local-service`

Command-Line Format	`--log-error[=file_name]`
System Variable	`log_error`
Scope	Global
Dynamic	No
Type	File name

Command-Line Format	`--log-isam[=file_name]`
Type	File name

Command-Line Format	`--log-raw[={OFF\|ON}]`
Type	Boolean
Default Value	`OFF`

Command-Line Format	`--log-short-format[={OFF\|ON}]`
Type	Boolean
Default Value	`OFF`

Command-Line Format	`--log-tc=file_name`
Type	File name
Default Value	`tc.log`

--log-tc-size=size

Command-Line Format	`--log-tc-size=#`
Type	Integer
Default Value (64-bit platforms, ≥ 5.7.21)	`6 * page size`
Default Value (64-bit platforms, ≤ 5.7.20)	`24576`
Default Value (32-bit platforms, ≥ 5.7.21)	`6 * page size`
Default Value (32-bit platforms, ≤ 5.7.20)	`24576`
Minimum Value	`6 * page size`
Maximum Value (64-bit platforms)	`18446744073709551615`
Maximum Value (32-bit platforms)	`4294967295`

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. (Before MySQL 5.7.21, the default size is 24KB.)

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

Command-Line Format	`--log-warnings[=#]`
Deprecated	Yes
System Variable	`log_warnings`
Scope	Global
Dynamic	Yes
Type	Integer
Default Value	`2`
Minimum Value	`0`
Maximum Value (64-bit platforms)	`18446744073709551615`
Maximum Value (32-bit platforms)	`4294967295`

Note

The log_error_verbosity system variable is preferred over, and should be used instead of, the --log-warnings option or log_warnings system variable. For more information, see the descriptions of log_error_verbosity and log_warnings. The --log-warnings command-line option and log_warnings system variable are deprecated; expect them to be removed in a future release of MySQL.

Whether to produce additional warning messages to the error log. This option is enabled by default. To disable it, use --log-warnings=0. Specifying the option without a level value increments the current value by 1. The server logs messages about statements that are unsafe for statement-based logging if the value is greater than 0. Aborted connections and access-denied errors for new connection attempts are logged if the value is greater than 1. See Section B.3.2.9, “Communication Errors and Aborted Connections”.

--memlock
Command-Line Format --memlock[={OFF|ON}]
Type Boolean
Default Value OFF
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:
```
$> 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;
```
Important
Use of this option may require you to run the server as root, which, for reasons of security, is normally not a good idea. See Section 6.1.5, “How to Run MySQL as a Normal User”.
On Linux and perhaps other systems, you can avoid the need to run the server as root by changing the limits.conf file. See the notes regarding the memlock limit in Section 8.12.4.2, “Enabling Large Page Support”.
You must not use this option on a system that does not support the mlockall() system call; if you do so, mysqld is very likely to exit as soon as you try to start it.
--myisam-block-size=N
Command-Line Format --myisam-block-size=#
Type Integer
Default Value 1024
Minimum Value 1024
Maximum Value 16384
The block size to be used for MyISAM 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, see Section 4.2.2.3, “Command-Line Options that Affect Option-File Handling”.
--old-style-user-limits
Command-Line Format --old-style-user-limits[={OFF|ON}]
Type Boolean
Default Value OFF
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 6.2.16, “Setting Account Resource Limits”.
--partition[=value]
Command-Line Format --partition[={OFF|ON}]
Deprecated 5.7.16
Disabled by skip-partition
Type Boolean
Default Value ON
Enables or disables user-defined partitioning support in the MySQL Server.
This option is deprecated in MySQL 5.7.16, and is removed from MySQL 8.0 because in MySQL 8.0, the partitioning engine is replaced by native partitioning, which cannot be disabled.
--performance-schema-xxx
Configure a Performance Schema option. For details, see Section 25.14, “Performance Schema Command Options”.
--plugin-load=plugin_list
Command-Line Format --plugin-load=plugin_list
System Variable plugin_load
Scope Global
Dynamic No
Type String
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 of plugin_library and name=plugin_library values. Each plugin_library is the name of a library file that contains plugin code, and each name 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 libary. 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 are contained in the plugin library files myplug1.so and myplug2.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 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.
During the normal startup sequence, 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, plugins registered in the mysql.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.
For additional information about plugin loading, see Section 5.5.1, “Installing and Uninstalling Plugins”.
--plugin-load-add=plugin_list
Command-Line Format --plugin-load-add=plugin_list
System Variable plugin_load_add
Scope Global
Dynamic No
Type String
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 5.5.1, “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 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 4.2.2.4, “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.
--port=port_num, -P port_num
Command-Line Format --port=port_num
System Variable port
Scope Global
Dynamic No
Type Integer
Default Value 3306
Minimum Value 0
Maximum Value 65535
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 operating system user. Setting this option to 0 causes the default value to be used.
--port-open-timeout=num
Command-Line Format --port-open-timeout=#
Type Integer
Default Value 0
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 4.2.2.3, “Command-Line Options that Affect Option-File Handling”.
--remove [service_name]
Command-Line Format --remove [service_name]
Platform Specific Windows
(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 2.3.4.8, “Starting MySQL as a Windows Service”.
--safe-user-create
Command-Line Format --safe-user-create[={OFF|ON}]
Type Boolean
Default Value OFF
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:
```
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 the GRANT statement to give privileges to other users.
--skip-grant-tables
Command-Line Format --skip-grant-tables[={OFF|ON}]
Type Boolean
Default Value OFF
This option affects the server startup sequence:
- --skip-grant-tables causes the server not to read the grant tables in the mysql system database, and thus to start without using the privilege system at all. This gives anyone with access to the server unrestricted access to all databases.
  To cause a server started with --skip-grant-tables to load the grant tables at runtime, perform a privilege-flushing operation, which can be done in these ways:
  - Issue a MySQL FLUSH PRIVILEGES statement after connecting to the server.
  - Execute a mysqladmin flush-privileges or mysqladmin reload command from the command line.
  Privilege flushing might also occur implicitly as a result of other actions performed after startup, thus causing the server to start using the grant tables. For example, mysql_upgrade flushes the privileges during the upgrade procedure.
- --skip-grant-tables causes the server not to load certain other objects registered in the mysql system database:
  - Plugins installed using INSTALL PLUGIN and registered in the mysql.plugin system table.
    To cause plugins to be loaded even when using --skip-grant-tables, use the --plugin-load or --plugin-load-add option.
  - Scheduled events installed using CREATE EVENT and registered in the mysql.event system table.
  - Loadable functions installed using CREATE FUNCTION and registered in the mysql.func system table.
- --skip-grant-tables causes the disabled_storage_engines system variable to have no effect.
--skip-host-cache
Command-Line Format --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.
Starting the server with --skip-host-cache does not prevent runtime 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 5.1.11.2, “DNS Lookups and the Host Cache”.
--skip-innodb
Disable the InnoDB storage engine. In this case, because the default storage engine is InnoDB, the server cannot 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. Expect this option to be removed in a future release of MySQL.
--skip-new
Command-Line Format --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 causes OPTIMIZE TABLE to be mapped to ALTER TABLE for storage engines for which OPTIMIZE TABLE is not supported.
--skip-partition
Command-Line Format
--skip-partition
--disable-partition

Deprecated 5.7.16
Disables user-defined partitioning. Partitioned tables can be seen using SHOW TABLES or by querying the INFORMATION_SCHEMA.TABLES table, but cannot be created or modified, nor can data in such tables be accessed. All partition-specific columns in the INFORMATION_SCHEMA.PARTITIONS table display NULL.
Since DROP TABLE removes table definition (.frm) files, this statement works on partitioned tables even when partitioning is disabled using the option. The statement, however, does not remove partition definitions associated with partitioned tables in such cases. For this reason, you should avoid dropping partitioned tables with partitioning disabled, or take action to remove orphaned .par files manually (if present).
Note
In MySQL 5.7, partition definition (.par) files are no longer created for partitioned InnoDB tables. Instead, partition definitions are stored in the InnoDB internal data dictionary. Partition definition (.par) files continue to be used for partitioned MyISAM tables.
This option is deprecated in MySQL 5.7.16, and is removed from MySQL 8.0 because in MySQL 8.0, the partitioning engine is replaced by native partitioning, which cannot be disabled.
--skip-show-database
Command-Line Format --skip-show-database
System Variable skip_show_database
Scope Global
Dynamic No
Type Boolean
Default Value OFF
This option sets the skip_show_database system variable that controls who is permitted to use the SHOW DATABASES statement. See Section 5.1.7, “Server System Variables”.
--skip-stack-trace
Command-Line Format --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 5.8, “Debugging MySQL”.
--slow-start-timeout=timeout
Command-Line Format --slow-start-timeout=#
Type Integer
Default Value 15000
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
Command-Line Format --socket={file_name|pipe_name}
System Variable socket
Scope Global
Dynamic No
Type String
Default Value (Windows) MySQL
Default Value (Other) /tmp/mysql.sock
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).

Command-Line Format	`--memlock[={OFF\|ON}]`
Type	Boolean
Default Value	`OFF`

Command-Line Format	`--myisam-block-size=#`
Type	Integer
Default Value	`1024`
Minimum Value	`1024`
Maximum Value	`16384`

Command-Line Format	`--old-style-user-limits[={OFF\|ON}]`
Type	Boolean
Default Value	`OFF`

Command-Line Format	`--partition[={OFF\|ON}]`
Deprecated	5.7.16
Disabled by	`skip-partition`
Type	Boolean
Default Value	`ON`

Command-Line Format	`--plugin-load=plugin_list`
System Variable	`plugin_load`
Scope	Global
Dynamic	No
Type	String

Command-Line Format	`--plugin-load-add=plugin_list`
System Variable	`plugin_load_add`
Scope	Global
Dynamic	No
Type	String

Command-Line Format	`--port=port_num`
System Variable	`port`
Scope	Global
Dynamic	No
Type	Integer
Default Value	`3306`
Minimum Value	`0`
Maximum Value	`65535`

Command-Line Format	`--port-open-timeout=#`
Type	Integer
Default Value	`0`

Command-Line Format	`--remove [service_name]`
Platform Specific	Windows

Command-Line Format	`--safe-user-create[={OFF\|ON}]`
Type	Boolean
Default Value	`OFF`

Command-Line Format	`--skip-grant-tables[={OFF\|ON}]`
Type	Boolean
Default Value	`OFF`

Command-Line Format	`--skip-host-cache`

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

Command-Line Format	`--sql-mode=name`
System Variable	`sql_mode`
Scope	Global, Session
Dynamic	Yes
Type	Set
Default Value	`ONLY_FULL_GROUP_BY STRICT_TRANS_TABLES NO_ZERO_IN_DATE NO_ZERO_DATE ERROR_FOR_DIVISION_BY_ZERO NO_AUTO_CREATE_USER NO_ENGINE_SUBSTITUTION`
Valid Values	`ALLOW_INVALID_DATES` `ANSI_QUOTES` `ERROR_FOR_DIVISION_BY_ZERO` `HIGH_NOT_PRECEDENCE` `IGNORE_SPACE` `NO_AUTO_CREATE_USER` `NO_AUTO_VALUE_ON_ZERO` `NO_BACKSLASH_ESCAPES` `NO_DIR_IN_CREATE` `NO_ENGINE_SUBSTITUTION` `NO_FIELD_OPTIONS` `NO_KEY_OPTIONS` `NO_TABLE_OPTIONS` `NO_UNSIGNED_SUBTRACTION` `NO_ZERO_DATE` `NO_ZERO_IN_DATE` `ONLY_FULL_GROUP_BY` `PAD_CHAR_TO_FULL_LENGTH` `PIPES_AS_CONCAT` `REAL_AS_FLOAT` `STRICT_ALL_TABLES` `STRICT_TRANS_TABLES`

Set the SQL mode. See Section 5.1.10, “Server SQL Modes”.

Note

MySQL installation programs may configure the SQL mode during the installation process. If the SQL mode differs from the default or from what you expect, check for a setting in an option file that the server reads at startup.

--ssl, --skip-ssl
Command-Line Format --ssl[={OFF|ON}]
Disabled by skip-ssl
Type Boolean
Default Value ON
The --ssl option specifies that the server permits but does not require encrypted connections. This option is enabled by default.
--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 does not permit encrypted connections, regardless of the settings of the tls_xxx and ssl_xxx system variables.
For more information about configuring whether the server permits clients to connect using SSL and indicating where to find SSL keys and certificates, see Section 6.3.1, “Configuring MySQL to Use Encrypted Connections”, which also describes server capabilities for certificate and key file autogeneration and autodiscovery. Consider setting at least the ssl_cert and ssl_key system variables on the server side and the --ssl-ca (or --ssl-capath) option on the client side.
--standalone
Command-Line Format --standalone
Platform Specific Windows
Available on Windows only; instructs the MySQL server not to run as a service.
--super-large-pages
Command-Line Format --super-large-pages[={OFF|ON}]
Platform Specific Solaris
Type Boolean
Default Value OFF
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
Command-Line Format --symbolic-links[={OFF|ON}]
Type Boolean
Default Value ON
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 8.12.3.2, “Using Symbolic Links for MyISAM Tables on Unix”.
This option has no meaning on Windows.
--sysdate-is-now
Command-Line Format --sysdate-is-now[={OFF|ON}]
Type Boolean
Default Value OFF
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 a synonym 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 5.1.7, “Server System Variables”.
--tc-heuristic-recover={COMMIT|ROLLBACK}
Command-Line Format --tc-heuristic-recover=name
Type Enumeration
Default Value OFF
Valid Values
OFF
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, the ROLLBACK option is not safe and causes recovery to halt with the following error:
```
[ERROR] --tc-heuristic-recover rollback
strategy is not safe on systems with more than one 2-phase-commit-capable
storage engine. Aborting crash recovery.
```
--temp-pool
Command-Line Format --temp-pool[={OFF|ON}]
Deprecated 5.7.18
Type Boolean
Default Value (Linux) ON
Default Value (Other) OFF
This option is ignored except on Linux. On Linux, it causes most temporary files created by the server to use a small set of names, rather than a unique name for each new file. This works around a problem in the Linux kernel dealing with creating many new files with different names. With the old behavior, Linux seems to “leak” memory, because it is being allocated to the directory entry cache rather than to the disk cache.
As of MySQL 5.7.18, this option is deprecated and is removed in MySQL 8.0.

--transaction-isolation=level

Command-Line Format	`--transaction-isolation=name`
System Variable (≥ 5.7.20)	`transaction_isolation`
Scope (≥ 5.7.20)	Global, Session
Dynamic (≥ 5.7.20)	Yes
Type	Enumeration
Default Value	`REPEATABLE-READ`
Valid Values	`READ-UNCOMMITTED` `READ-COMMITTED` `REPEATABLE-READ` `SERIALIZABLE`

Sets the default transaction isolation level. The level value can be READ-UNCOMMITTED, READ-COMMITTED, REPEATABLE-READ, or SERIALIZABLE. See Section 13.3.6, “SET TRANSACTION Statement”.

The default transaction isolation level can also be set at runtime using the SET TRANSACTION statement or by setting the tx_isolation (or, as of MySQL 5.7.20, transaction_isolation) system variable.

--transaction-read-only
Command-Line Format --transaction-read-only[={OFF|ON}]
System Variable (≥ 5.7.20) transaction_read_only
Scope (≥ 5.7.20) Global, Session
Dynamic (≥ 5.7.20) Yes
Type Boolean
Default Value OFF
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 tx_read_only (or, as of MySQL 5.7.20, transaction_read_only) system variable. See Section 13.3.6, “SET TRANSACTION Statement”.
--tmpdir=dir_name, -t dir_name
Command-Line Format --tmpdir=dir_name
System Variable tmpdir
Scope Global
Dynamic No
Type Directory 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 the slave_load_tmpdir system variable. For a replication replica, the temporary files used to replicate LOAD 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, see Section B.3.3.5, “Where MySQL Stores Temporary Files”.
--user={user_name|user_id}, -u {user_name|user_id}
Command-Line Format --user=name
Type String
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-user-plugins[={OFF|ON}]
Command-Line Format --validate-user-plugins[={OFF|ON}]
Type Boolean
Default Value 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:
- The account requires an authentication plugin that is not loaded.
- The account requires the sha256_password authentication plugin but the server was started with neither SSL nor RSA enabled as required by this plugin.
Enabling --validate-user-plugins slows down server initialization and FLUSH 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.

Command-Line Format	`--skip-show-database`
System Variable	`skip_show_database`
Scope	Global
Dynamic	No
Type	Boolean
Default Value	`OFF`

Command-Line Format	`--slow-start-timeout=#`
Type	Integer
Default Value	`15000`

Command-Line Format	`--socket={file_name\|pipe_name}`
System Variable	`socket`
Scope	Global
Dynamic	No
Type	String
Default Value (Windows)	`MySQL`
Default Value (Other)	`/tmp/mysql.sock`

Command-Line Format	`--ssl[={OFF\|ON}]`
Disabled by	`skip-ssl`
Type	Boolean
Default Value	`ON`

Command-Line Format	`--super-large-pages[={OFF\|ON}]`
Platform Specific	Solaris
Type	Boolean
Default Value	`OFF`

Command-Line Format	`--symbolic-links[={OFF\|ON}]`
Type	Boolean
Default Value	`ON`

Command-Line Format	`--sysdate-is-now[={OFF\|ON}]`
Type	Boolean
Default Value	`OFF`

Command-Line Format	`--tc-heuristic-recover=name`
Type	Enumeration
Default Value	`OFF`
Valid Values	`OFF` `COMMIT` `ROLLBACK`

Command-Line Format	`--temp-pool[={OFF\|ON}]`
Deprecated	5.7.18
Type	Boolean
Default Value (Linux)	`ON`
Default Value (Other)	`OFF`

Command-Line Format	`--transaction-read-only[={OFF\|ON}]`
System Variable (≥ 5.7.20)	`transaction_read_only`
Scope (≥ 5.7.20)	Global, Session
Dynamic (≥ 5.7.20)	Yes
Type	Boolean
Default Value	`OFF`

Command-Line Format	`--tmpdir=dir_name`
System Variable	`tmpdir`
Scope	Global
Dynamic	No
Type	Directory name

Command-Line Format	`--validate-user-plugins[={OFF\|ON}]`
Type	Boolean
Default Value	`ON`