4.3.2 mysqld_safe — MySQL Server Startup Script

mysqld_safe 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. Descriptions of error logging and NetWare-specific behaviors are given later in this section.

Note

In MySQL 5.1.20 (only), the default error logging behavior with mysqld_safe is to write errors to syslog on systems that support the logger program. This differs from the default behavior of writing an error log file for other versions.

In 5.1.20, logging to syslog may fail to operate correctly in some cases; if so, use --skip-syslog to use the default log file or --log-error=file_name to specify a log file name explicitly.

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 4.2.3.3, “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 you should rename such sections to [mysqld_safe] in MySQL 5.1 installations.

mysqld_safe supports the options in the following list. It also reads option files and supports the options for processing them described at Section 4.2.3.4, “Command-Line Options that Affect Option-File Handling”.

Table 4.1 mysqld_safe Options

FormatOption FileDescriptionIntroduced
--autocloseautocloseOn NetWare, mysqld_safe provides a screen presence 
--basedir=pathbasedirThe path to the MySQL installation directory 
--core-file-size=sizecore-file-sizeThe size of the core file that mysqld should be able to create 
--datadir=pathdatadirThe path to the data directory 
--defaults-extra-file=pathdefaults-extra-fileRead option file in addition to the usual option files 
--defaults-file=file_namedefaults-fileRead only the given option file 
--help Display a help message and exit 
--ledir=pathledirUse this option to indicate the path name to the directory where the server is located 
--log-error=file_namelog-errorWrite the error log to the given file 
--mysqld=prog_namemysqldThe name of the server program (in the ledir directory) that you want to start 
--mysqld-version=suffixmysqld-versionThis option is similar to the --mysqld option, but you specify only the suffix for the server program name 
--nice=priorityniceUse the nice program to set the server's scheduling priority to the given value 
--no-defaultsno-defaultsDo not read any option files 
--open-files-limit=countopen-files-limitThe number of files that mysqld should be able to open 
--pid-file=file_namepid-file=file_nameThe path name of the process ID file 
--port=numberportThe port number that the server should use when listening for TCP/IP connections 
--skip-kill-mysqldskip-kill-mysqldDo not try to kill stray mysqld processes 
--skip-syslogskip-syslogDo not write error messages to syslog; use error log file5.1.20
--socket=pathsocketThe Unix socket file that the server should use when listening for local connections 
--syslogsyslogWrite error messages to syslog5.1.20
--syslog-tag=tagsyslog-tagTag suffix for messages written to syslog5.1.21
--timezone=timezonetimezoneSet the TZ time zone environment variable to the given option value 
--user={user_name|user_id}userRun 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_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.

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.

As of MySQL 5.1.20, 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.

Note

In MySQL 5.1.20 only, the default is --syslog. This differs from logging behavior for other versions of MySQL, for which the default is to write messages to the default error log file.

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.

Before MySQL 5.1.20, error logging is controlled only with the --log-error option. If it is given, messages go to the named error file. Otherwise, messages go to the default error file.

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:

  1. Runs a number of system and option checks.

  2. Runs a check on MyISAM tables.

  3. Provides a screen presence for the MySQL server.

  4. Starts mysqld, monitors it, and restarts it if it terminates in error.

  5. Sends error messages from mysqld to the host_name.err file in the data directory.

  6. Sends mysqld_safe screen output to the host_name.safe file in the data directory.