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 file. A description of error logging is given later in this section.

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 5.1.3, "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, "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:


For backward compatibility, mysqld_safe also reads [safe_mysqld] sections, although you should rename such sections to [mysqld_safe] in MySQL 5.7 installations.

mysqld_safe supports the following options. It also reads option files and supports the options for processing them described at Section, "Command-Line Options that Affect Option-File Handling".

Table 4.1. mysqld_safe Options

Format Option File Description
--basedir=path basedir The path to the MySQL installation directory
--core-file-size=size core-file-size The size of the core file that mysqld should be able to create
--datadir=path datadir The path to the data directory
--defaults-extra-file=path defaults-extra-file The name of an option file to be read in addition to the usual option files
--defaults-file=file_name defaults-file The name of an option file to be read instead of the usual option files
--help Display a help message and exit
--ledir=path ledir Use this option to indicate the path name to the directory where the server is located
--log-error=file_name log-error Write the error log to the given file
--malloc-lib=[lib-name] malloc-lib Alternative malloc library to use for mysqld
--mysqld=prog_name mysqld The name of the server program (in the ledir directory) that you want to start
--mysqld-version=suffix mysqld-version This option is similar to the --mysqld option, but you specify only the suffix for the server program name
--nice=priority nice Use the nice program to set the server's scheduling priority to the given value
--no-defaults no-defaults Do not read any option files
--open-files-limit=count open-files-limit The number of files that mysqld should be able to open
--pid-file=file_name pid-file=file_name The path name of the process ID file
--plugin-dir=path plugin-dir=path The directory where plugins are located
--port=number port The port number that the server should use when listening for TCP/IP connections
--skip-kill-mysqld skip-kill-mysqld Do not try to kill stray mysqld processes
--skip-syslog skip-syslog Do not write error messages to syslog; use error log file
--socket=path socket The Unix socket file that the server should use when listening for local connections
--syslog syslog Write error messages to syslog
--syslog-tag=tag syslog-tag Tag suffix for messages written to syslog
--timezone=timezone timezone Set the TZ time zone environment variable to the given option value
--user={user_name|user_id} user Run the mysqld server as the user having the name user_name or the 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 2.1.5, "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_directoryshell> 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.

In MySQL 5.7, mysqld_safe tries to use the sleep and date system utilities to determine how many times it has attempted to start this second, and—if these are present and this is greater than 5 times—is forced to wait 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.

If --syslog and --log-error are both given, a warning is issued and --log-error takes precedence.

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.

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.

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