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Section: MySQL Database System (1)
Updated: 11/15/2007
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mysqld_safe - MySQL server startup script
safe_mysqld - MySQL server startup script  


mysqld_safe options



is the recommended way to start a mysqld server on Unix and NetWare. mysqld_safe adds some safety features such as restarting the server when an error occurs and logging runtime information to an error log file. NetWare-specific behaviors are listed later in this section.


To preserve backward compatibility with older versions of MySQL, MySQL binary distributions still include safe_mysqld as a symbolic link to mysqld_safe. However, you should not rely on this because it is removed as of MySQL 5.1.

By default, mysqld_safe before MySQL 5.0.27 tries to start an executable named mysqld-max if it exists, and mysqld otherwise. Be aware of the implications of this behavior:

On Linux, the MySQL-Max RPM relies on this mysqld_safe behavior. The RPM installs an executable named mysqld-max, which causes mysqld_safe to automatically use that executable rather than mysqld from that point on.
If you install a MySQL-Max distribution that includes a server named mysqld-max, and then upgrade later to a non-Max version of MySQL, mysqld_safe will still attempt to run the old mysqld-max server. If you perform such an upgrade, you should manually remove the old mysqld-max server to ensure that mysqld_safe runs the new mysqld server.

To override the default behavior and specify explicitly the name of the server you want to run, specify a --mysqld or --mysqld-version option to mysqld_safe. You can also use --ledir to indicate the directory where mysqld_safe should look for the server.

Many of the options to mysqld_safe are the same as the options to mysqld. See the section called lqCOMMAND OPTIONSrq.

All options specified to mysqld_safe on the command line are passed to mysqld. If you want to use any options that are specific to mysqld_safe and that mysqld doesn't support, do not specify them on the command line. Instead, list them in the [mysqld_safe] group of an option file. See Section 3.2, lqUsing Option Filesrq.

mysqld_safe reads all options from the [mysqld], [server], and [mysqld_safe] sections in option files. For example, if you specify a [mysqld] section like this, mysqld_safe will find and use the --log-error option:


For backward compatibility, mysqld_safe also reads [safe_mysqld] sections, although you should rename such sections to [mysqld_safe] in MySQL 5.0 installations.

mysqld_safe supports the following options:


Display a help message and exit. (Added in MySQL 5.0.3)


(NetWare only) On NetWare, mysqld_safe provides a screen presence. When you unload (shut down) the mysqld_safe NLM, the screen does not by default go away. Instead, it prompts for user input:

*<NLM has terminated; Press any key to close the screen>*
If you want NetWare to close the screen automatically instead, use the --autoclose option to mysqld_safe.

The path to the MySQL installation directory.


The size of the core file that mysqld should be able to create. The option value is passed to ulimit -c.


The path to the data directory.


The name of an option file to be read in addition to the usual option files. This must be the first option on the command line if it is used. As of MySQL 5.0.6, if the file does not exist or is otherwise inaccessible, the server will exit with an error.


The name of an option file to be read instead of the usual option files. This must be the first option on the command line if it is used.


If mysqld_safe cannot find the server, use this option to indicate the pathname to the directory where the server is located.


Write the error log to the given file. See Section 8.1, lqThe Error Logrq.


The name of the server program (in the ledir directory) that you want to start. This option is needed if you use the MySQL binary distribution but have the data directory outside of the binary distribution. If mysqld_safe cannot find the server, use the --ledir option to indicate the pathname to the directory where the server is located.


This option is similar to the --mysqld option, but you specify only the suffix for the server program name. The basename is assumed to be mysqld. For example, if you use --mysqld-version=debug, mysqld_safe starts the mysqld-debug program in the ledir directory. If the argument to --mysqld-version is empty, mysqld_safe uses mysqld in the ledir directory.


Use the nice program to set the server's scheduling priority to the given value.


Do not read any option files. This must be the first option on the command line if it is used.


The number of files that mysqld should be able to open. The option value is passed to ulimit -n. Note that you need to start mysqld_safe as root for this to work properly!


The pathname of the process ID file.


The port number that the server should use when listening for TCP/IP connections. The port number must be 1024 or higher unless the server is started by the root system user.


Do not try to kill stray mysqld processes at startup. This option works only on Linux.


The Unix socket file that the server should use when listening for local connections.


Set the TZ time zone environment variable to the given option value. Consult your operating system documentation for legal time zone specification formats.


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

If you execute mysqld_safe with the --defaults-file or --defaults-extra-option option to name an option file, the option must be the first one given on the command line or the option file will not be used. For example, this command will not use the named option file:

mysql> mysqld_safe --port=port_num --defaults-file=file_name

Instead, use the following command:

mysql> mysqld_safe --defaults-file=file_name --port=port_num

The mysqld_safe script is written so that it normally can start a server that was installed from either a source or a binary distribution of MySQL, even though these types of distributions typically install the server in slightly different locations. (See Section 4.6, lqInstallation Layoutsrq.) mysqld_safe expects one of the following conditions to be true:

The server and databases can be found relative to the working directory (the directory from which mysqld_safe is invoked). For binary distributions, mysqld_safe looks under its working directory for bin and data directories. For source distributions, it looks for libexec and var directories. This condition should be met if you execute mysqld_safe from your MySQL installation directory (for example, /usr/local/mysql for a binary distribution).
If the server and databases cannot be found relative to the working directory, mysqld_safe attempts to locate them by absolute pathnames. Typical locations are /usr/local/libexec and /usr/local/var. The actual locations are determined from the values configured into the distribution at the time it was built. They should be correct if MySQL is installed in the location specified at configuration time.

Because mysqld_safe tries to find the server and databases relative to its own working directory, you can install a binary distribution of MySQL anywhere, as long as you run mysqld_safe from the MySQL installation directory:

shell> cd mysql_installation_directory
shell> bin/mysqld_safe &

If mysqld_safe fails, even when invoked from the MySQL installation directory, you can specify the --ledir and --datadir options to indicate the directories in which the server and databases are located on your system.

Normally, you should not edit the mysqld_safe script. Instead, configure mysqld_safe by using command-line options or options in the [mysqld_safe] section of a my.cnf option file. In rare cases, it might be necessary to edit mysqld_safe to get it to start the server properly. However, if you do this, your modified version of mysqld_safe might be overwritten if you upgrade MySQL in the future, so you should make a copy of your edited version that you can reinstall.

On NetWare, mysqld_safe is a NetWare Loadable Module (NLM) that is ported from the original Unix shell script. It starts the server as follows:

Runs a number of system and option checks.
Runs a check on MyISAM tables.
Provides a screen presence for the MySQL server.
Starts mysqld, monitors it, and restarts it if it terminates in error.
Sends error messages from mysqld to the host_name.err file in the data directory.
Sends mysqld_safe screen output to the file in the data directory.


Copyright 2007 MySQL AB

This documentation is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; version 2 of the License.

This documentation is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

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For more information, please refer to the MySQL Reference Manual, which may already be installed locally and which is also available online at  






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