MySQL 8.0 Reference Manual Including MySQL NDB Cluster 8.0

4.3.2 mysqld_safe — MySQL Server Startup Script

mysqld_safe is the recommended way to start a mysqld server on Unix. mysqld_safe adds some safety features such as restarting the server when an error occurs and logging runtime information to an error log. A description of error logging is given later in this section.

Note

For some Linux platforms, MySQL installation from RPM or Debian packages includes systemd support for managing MySQL server startup and shutdown. On these platforms, mysqld_safe is not installed because it is unnecessary. For more information, see Section 2.5.9, “Managing MySQL Server with systemd”.

mysqld_safe tries to start an executable named mysqld. 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 Section 5.1.7, “Server Command Options”.

Options unknown to mysqld_safe are passed to mysqld if they are specified on the command line, but ignored if they are specified in the [mysqld_safe] group of an option file. See Section 4.2.2.2, “Using Option Files”.

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:

[mysqld]
log-error=error.log

For backward compatibility, mysqld_safe also reads [safe_mysqld] sections, but to be current you should rename such sections to [mysqld_safe].

mysqld_safe accepts options on the command line and in option files, as described in the following table. For information about option files used by MySQL programs, see Section 4.2.2.2, “Using Option Files”.

Table 4.6 mysqld_safe Options

Option Name Description
--basedir Path to MySQL installation directory
--core-file-size Size of core file that mysqld should be able to create
--datadir Path to data directory
--defaults-extra-file Read named option file in addition to usual option files
--defaults-file Read only named option file
--help Display help message and exit
--ledir Path to directory where server is located
--log-error Write error log to named file
--malloc-lib Alternative malloc library to use for mysqld
--mysqld Name of server program to start (in ledir directory)
--mysqld-safe-log-timestamps Timestamp format for logging
--mysqld-version Suffix for server program name
--nice Use nice program to set server scheduling priority
--no-defaults Read no option files
--open-files-limit Number of files that mysqld should be able to open
--pid-file Path name of server process ID file
--plugin-dir Directory where plugins are installed
--port Port number on which to listen for TCP/IP connections
--skip-kill-mysqld Do not try to kill stray mysqld processes
--skip-syslog Do not write error messages to syslog; use error log file
--socket Socket file on which to listen for Unix socket connections
--syslog Write error messages to syslog
--syslog-tag Tag suffix for messages written to syslog
--timezone Set TZ time zone environment variable to named value
--user Run mysqld as user having name user_name or numeric user ID user_id

If you execute mysqld_safe with the --defaults-file or --defaults-extra-file 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 2.1.4, “Installation Layouts”.) mysqld_safe expects one of the following conditions to be true:

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, specify the --ledir and --datadir options to indicate the directories in which the server and databases are located on your system.

mysqld_safe tries to use the sleep and date system utilities to determine how many times per second it has attempted to start. If these utilities are present and the attempted starts per second is greater than 5, mysqld_safe waits 1 full second before starting again. This is intended to prevent excessive CPU usage in the event of repeated failures. (Bug #11761530, Bug #54035)

When you use mysqld_safe to start mysqld, mysqld_safe arranges for error (and notice) messages from itself and from mysqld to go to the same destination.

There are several mysqld_safe options for controlling the destination of these messages:

If none of these options is given, the default is --skip-syslog.

When mysqld_safe writes a message, notices go to the logging destination (syslog or the error log file) and stdout. Errors go to the logging destination and stderr.

Note

Controlling mysqld logging from mysqld_safe is deprecated. Use the server's native syslog support instead. For more information, see Section 5.4.2.7, “Error Logging to the System Log”.