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 4.2.6, “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, although it is preferable to rename [safe_mysqld] sections to [mysqld_safe] sections.

mysqld_safe supports the following options. It also reads option files and supports the options for processing them described at Section 4.2.7, “Command-Line Options that Affect Option-File Handling”.

Table 4.1 mysqld_safe Options

FormatDescriptionIntroduced
--basedir=pathPath to MySQL installation directory 
--core-file-size=sizeSize of core file that mysqld should be able to create 
--datadir=pathPath to data directory 
--defaults-extra-file=file_nameRead option file in addition to usual option files 
--defaults-file=file_nameRead only named option file 
--helpDisplay help message and exit 
--ledir=pathPath to directory where server is located 
--log-error=file_nameWrite error log to named file 
--malloc-lib=[lib-name]Alternative malloc library to use for mysqld 
--mysqld=prog_nameName of server program to start (in ledir directory) 
--mysqld-version=suffixSuffix for server program name 
--nice=priorityUse nice program to set server scheduling priority 
--no-defaultsRead no option files 
--open-files-limit=countNumber of files that mysqld should be able to open 
--pid-file=file_namePath name of process ID file 
--plugin-dir=pathDirectory where plugins are installed5.5.3
--port=numberPort number on which to listen for TCP/IP connections 
--skip-kill-mysqldDo not try to kill stray mysqld processes 
--skip-syslogDo not write error messages to syslog; use error log file 
--socket=pathSocket file on which to listen for Unix socket connections 
--syslogWrite error messages to syslog 
--syslog-tag=tagTag suffix for messages written to syslog 
--timezone=timezoneSet TZ time zone environment variable to named value 
--user={user_name|user_id}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 2.1.5, “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_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.

Beginning with MySQL 5.5.21, 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 --log-error and --syslog 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.