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.
As of MySQL 5.7.6, for MySQL installation using an RPM distribution, server startup and shutdown is managed by systemd on several Linux platforms. On these platforms, mysqld_safe is no longer installed because it is unnecessary. For more information, see Section 2.5.10, “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
to mysqld_safe. You can also use
--ledir to indicate the
directory where mysqld_safe should look for
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_safe] sections in option files. For
example, if you specify a
like this, mysqld_safe will find and use the
For backward compatibility, mysqld_safe also
[safe_mysqld] sections, but to be
current you should rename such sections to
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 4.2.6, “Using Option Files”.
|--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-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 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|
Display a help message and exit.
The path to the MySQL installation directory.
The size of the core file that mysqld should be able to create. The option value is passed to ulimit -c.
The path to the data directory.
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.
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.
If mysqld_safe cannot find the server, use this option to indicate the path name to the directory where the server is located.
Write the error log to the given file. See Section 5.2.2, “The Error Log”.
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
tcmalloclibrary that is shipped with binary MySQL distributions for Linux in MySQL 5.7. It is possible that the shortcut form will not work under certain configurations, in which case you should specify a path name instead.
If the option is not given, or is given without a value (
LD_PRELOADis not modified and no attempt is made to use
If the option is given as
--malloc-lib=tcmalloc, mysqld_safe looks for a
/usr/liband then in the MySQL
pkglibdirlocation (for example,
/usr/local/mysql/libor whatever is appropriate). If
tmallocis found, its path name is added to the beginning of the
LD_PRELOADvalue for mysqld. If
tcmallocis not found, mysqld_safe aborts with an error.
If the option is given as
--malloc-lib=, that full path is added to the beginning of the
LD_PRELOADvalue. If the full path points to a nonexistent or unreadable file, mysqld_safe aborts with an error.
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.
On systems that manage the server using systemd, mysqld_safe is not available. Instead, specify the allocation library by setting
Linux users can use the
libtcmalloc_minimal.soincluded in binary packages by adding these lines to the
Those lines also suffice for users on any platform who have installed a
/usr/lib. To use a specific
tcmalloclibrary, specify its full path name. Example:
The name of the server program (in the
ledirdirectory) 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
--lediroption to indicate the path name to the directory where the server is located.
This option is similar to the
--mysqldoption, but you specify only the suffix for the server program name. The base name is assumed to be mysqld. For example, if you use
--mysqld-version=debug, mysqld_safe starts the mysqld-debug program in the
ledirdirectory. If the argument to
--mysqld-versionis empty, mysqld_safe uses mysqld in the
niceprogram to set the server's scheduling priority to the given value.
Do not read any option files. This must be the first option on the command line if it is used.
The number of files that mysqld should be able to open. The option value is passed to ulimit -n.Note
You must start mysqld_safe as
rootfor this to function properly.
The path name of the process ID file.
In MySQL 5.7.2 and later, mysqld_safe creates a PID file named
mysqld_safe.pidin the MySQL data directory when starting up (Bug #16776528).
The path name of the plugin directory.
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
Do not try to kill stray mysqld processes at startup. This option works only on Linux.
The Unix socket file that the server should use when listening for local connections.
--syslogcauses error messages to be sent to
syslogon systems that support the logger program.
--skip-syslogsuppresses the use of
syslog; messages are written to an error log file.
syslogis used, the
daemon.errfacility/severity is used for all log messages.
Using these options to control mysqld logging is deprecated as of MySQL 5.7.5. Use the server
log_syslogsystem variable instead. To control the facility, use the server
log_syslog_facilitysystem variable. See Section 5.2.2, “The Error Log”.
For logging to
syslog, messages from mysqld_safe and mysqld are written with identifiers of
mysqld, respectively. To specify a suffix for the identifiers, use
--syslog-tag=, which modifies the identifiers to be
TZtime zone environment variable to the given option value. Consult your operating system documentation for legal time zone specification formats.
Run the mysqld server as the user having the name
user_nameor 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
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:
Instead, use the following command:
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:
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
datadirectories. For source distributions, it looks for
vardirectories. This condition should be met if you execute mysqld_safe from your MySQL installation directory (for example,
/usr/local/mysqlfor a binary distribution).
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/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:
If mysqld_safe fails, even when invoked from
the MySQL installation directory, specify the
--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)
There are several mysqld_safe options for controlling the destination of these messages:
--log-error=: Write error messages to the named error file.
--syslog: Write error messages to
syslogon systems that support the logger program.
If none of these options is given, the default is
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