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Updated: July 2014

mysqld_safe (1)


mysqld_safe - MySQL server startup script


mysqld_safe options


MySQL Database System                              MYSQLD_SAFE(1)

     mysqld_safe - MySQL server startup script

     mysqld_safe options

     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 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 5.5 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".

     o   --help

         Display a help message and exit.

     o   --basedir=path

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         The path to the MySQL installation directory.

     o   --core-file-size=size

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

     o   --datadir=path

         The path to the data directory.

     o   --defaults-extra-file=path

         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. If the file does not exist
         or is otherwise inaccessible, the server will exit with
         an error.

     o   --defaults-file=file_name

         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.

     o   --ledir=path

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

     o   --log-error=file_name

         Write the error log to the given file. See
         Section 5.2.2, "The Error Log".

     o   --malloc-lib=[lib_name]

         The name of the library to use for memory allocation
         instead of the system malloc() library. Any library can
         be used by specifying its path name, but there is a
         shortcut form to enable use of the tcmalloc library that
         is shipped with binary MySQL distributions for Linux in
         MySQL 5.5.

         The --malloc-lib option works by modifying the
         LD_PRELOAD environment value to affect dynamic linking
         to enable the loader to find the memory-allocation
         library when mysqld runs:

         o   If the option is not given, or is given without a
             value (--malloc-lib=), LD_PRELOAD is not modified

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             and no attempt is made to use tcmalloc.

         o   If the option is given as --malloc-lib=tcmalloc,
             mysqld_safe looks for a tcmalloc library in /usr/lib
             and then in the MySQL pkglibdir location (for
             example, /usr/local/mysql/lib or whatever is
             appropriate). If tmalloc is found, its path name is
             added to the beginning of the LD_PRELOAD value for
             mysqld. If tcmalloc is not found, mysqld_safe aborts
             with an error.

         o   If the option is given as
             --malloc-lib=/path/to/some/library, that full path
             is added to the beginning of the LD_PRELOAD value.
             If the full path points to a nonexistent or
             unreadable file, mysqld_safe aborts with an error.

         o   For cases where mysqld_safe adds a path name to
             LD_PRELOAD, it adds the path to the beginning of any
             existing value the variable already has.

         Linux users can use the included
         in binary packages by adding these lines to the my.cnf


         Those lines also suffice for users on any platform who
         have installed a tcmalloc package in /usr/lib. To use a
         specific tcmalloc library, specify its full path name.


     o   --mysqld=prog_name

         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 path name to the directory where
         the server is located.

     o   --mysqld-version=suffix

         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

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         mysqld-debug program in the ledir directory. If the
         argument to --mysqld-version is empty, mysqld_safe uses
         mysqld in the ledir directory.

     o   --nice=priority

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

     o   --no-defaults

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

     o   --open-files-limit=count

         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

     o   --pid-file=file_name

         The path name of the process ID file.

     o   --plugin-dir=path

         The path name of the plugin directory. This option was
         added in MySQL 5.5.3.

     o   --port=port_num

         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.

     o   --skip-kill-mysqld

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

     o   --socket=path

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

     o   --syslog, --skip-syslog

         --syslog causes error messages to be sent to syslog on
         systems that support the logger program.  --skip-syslog
         suppresses the use of syslog; messages are written to an

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         error log file.

         When syslog is used, the daemon.err syslog
         priority/facility is used for all log messages.

     o   --syslog-tag=tag

         For logging to syslog, messages from mysqld_safe and
         mysqld are written with a tag of mysqld_safe and mysqld,
         respectively. To specify a suffix for the tag, use
         --syslog-tag=tag, which modifies the tags to be
         mysqld_safe-tag and mysqld-tag.

     o   --timezone=timezone

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

     o   --user={user_name|user_id}

         Run the mysqld server as the user having the name
         user_name or the numeric user ID user_id. ("User" 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-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:

     o   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

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         met if you execute mysqld_safe from your MySQL
         installation directory (for example, /usr/local/mysql
         for a binary distribution).

     o   If the server and databases cannot be found relative to
         the working directory, mysqld_safe attempts to locate
         them by absolute path names. 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.

     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:

     o   --syslog: Write error messages to syslog on systems that
         support the logger program.

     o   --skip-syslog: Do not write error messages to syslog.
         Messages are written to the default error log file
         (host_name.err in the data directory), or to a named
         file if the --log-error option is given.

     o   --log-error=file_name: Write error messages to the named
         error file.

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     If none of these options is given, the default is

     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

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