Rechercher dans le manuel MySQL
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. A description of error logging is given later in this section.
For some Linux platforms, MySQL installation from RPM or Debian packages includes systemd support for managing MySQL server startup and shutdown. On these platforms, mysqld_safe is not installed because it is unnecessary. For more information, see Section 2.5.9, “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 --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 5.1.7, “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 4.2.2.2, “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, but to be
current you should rename such sections to
[mysqld_safe]
.
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 4.2.2.2, “Using Option Files”.
Table 4.6 mysqld_safe Options
Option Name | Description |
---|---|
--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-safe-log-timestamps | Timestamp format for logging |
--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 server 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.
NoteThe
innodb_buffer_pool_in_core_file
variable can be used to reduce the size of core files on operating systems that support it. For more information, see Section 15.8.3.8, “Excluding Buffer Pool Pages from Core Files”.The path to the data directory.
--defaults-extra-file=
file_name
Read this option file in addition to the usual option files. If the file does not exist or is otherwise inaccessible, the server will exit with an error.
file_name
is interpreted relative to the current directory if given as a relative path name rather than a full path name. This must be the first option on the command line if it is used.For additional information about this and other option-file options, see Section 4.2.2.3, “Command-Line Options that Affect Option-File Handling”.
Use only the given option file. If the file does not exist or is otherwise inaccessible, the server will exit with an error.
file_name
is interpreted relative to the current directory if given as a relative path name rather than a full path name. This must be the first option on the command line if it is used.For additional information about this and other option-file options, see Section 4.2.2.3, “Command-Line Options that Affect Option-File Handling”.
If mysqld_safe cannot find the server, use this option to indicate the path name to the directory where the server is located.
This option is accepted only on the command line, not in option files. On platforms that use systemd, the value can be specified in the value of
MYSQLD_OPTS
. See Section 2.5.9, “Managing MySQL Server with systemd”.Write the error log to the given file. See Section 5.4.2, “The Error Log”.
This option controls the format for timestamps in log output produced by mysqld_safe. The following list describes the permitted values. For any other value, mysqld_safe logs a warning and uses
UTC
format.UTC
,utc
ISO 8601 UTC format (same as
--log_timestamps=UTC
for the server). This is the default.SYSTEM
,system
ISO 8601 local time format (same as
--log_timestamps=SYSTEM
for the server).HYPHEN
,hyphen
YY-MM-DD h:mm:ss
format, as in mysqld_safe for MySQL 5.6.LEGACY
,legacy
YYMMDD hh:mm:ss
format, as in mysqld_safe prior to MySQL 5.6.
The name of the library to use for memory allocation instead of the system
malloc()
library. The option value must be one of the directories/usr/lib
,/usr/lib64
,/usr/lib/i386-linux-gnu
, or/usr/lib/x86_64-linux-gnu
.The
--malloc-lib
option works by modifying theLD_PRELOAD
environment value to affect dynamic linking to enable the loader to find the memory-allocation library when mysqld runs:If the option is not given, or is given without a value (
--malloc-lib=
),LD_PRELOAD
is not modified and no attempt is made to usetcmalloc
.If the option is given as
--malloc-lib=tcmalloc
, mysqld_safe looks for atcmalloc
library in/usr/lib
. Iftmalloc
is found, its path name is added to the beginning of theLD_PRELOAD
value for mysqld. Iftcmalloc
is 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/path/to/some/library
LD_PRELOAD
value. 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.
NoteOn systems that manage the server using systemd, mysqld_safe is not available. Instead, specify the allocation library by setting
LD_PRELOAD
in/etc/sysconfig/mysql
.Linux users can use the
libtcmalloc_minimal.so
library on any platform for which atcmalloc
package is installed in/usr/lib
by adding these lines to themy.cnf
file:[mysqld_safe] malloc-lib=tcmalloc
To use a specific
tcmalloc
library, specify its full path name. Example:[mysqld_safe] malloc-lib=/opt/lib/libtcmalloc_minimal.so
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.This option is accepted only on the command line, not in option files. On platforms that use systemd, the value can be specified in the value of
MYSQLD_OPTS
. See Section 2.5.9, “Managing MySQL Server with systemd”.This option is similar to the
--mysqld
option, 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 theledir
directory. If the argument to--mysqld-version
is empty, mysqld_safe uses mysqld in theledir
directory.This option is accepted only on the command line, not in option files. On platforms that use systemd, the value can be specified in the value of
MYSQLD_OPTS
. See Section 2.5.9, “Managing MySQL Server with systemd”.Use the
nice
program to set the server's scheduling priority to the given value.Do not read any option files. If program startup fails due to reading unknown options from an option file,
--no-defaults
can be used to prevent them from being read. This must be the first option on the command line if it is used.For additional information about this and other option-file options, see Section 4.2.2.3, “Command-Line Options that Affect Option-File Handling”.
The number of files that mysqld should be able to open. The option value is passed to ulimit -n.
NoteYou must start mysqld_safe as
root
for this to function properly.The path name that mysqld should use for its process ID file.
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
root
operating system user.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.
--syslog
causes error messages to be sent tosyslog
on systems that support the logger program.--skip-syslog
suppresses the use ofsyslog
; messages are written to an error log file.When
syslog
is used for error logging, thedaemon.err
facility/severity is used for all log messages.Using these options to control mysqld logging is deprecated. To write error log output to the system log, use the instructions at Section 5.4.2.7, “Error Logging to the System Log”. To control the facility, use the server
log_syslog_facility
system variable.For logging to
syslog
, messages from mysqld_safe and mysqld are written with identifiers ofmysqld_safe
andmysqld
, respectively. To specify a suffix for the identifiers, use--syslog-tag=
, which modifies the identifiers to betag
mysqld_safe-
andtag
mysqld-
.tag
Using this option to control mysqld logging is deprecated. Use the server
log_syslog_tag
system variable instead. See Section 5.4.2.7, “Error Logging to the System Log”.Set the
TZ
time 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_name
or the numeric user IDuser_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 2.1.4, “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
bin
anddata
directories. For source distributions, it looks forlibexec
andvar
directories. This condition should be met if you execute mysqld_safe from your MySQL installation directory (for example,/usr/local/mysql
for 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/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, specify the
--ledir
and
--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)
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:
--log-error=
: Write error messages to the named error file.file_name
--syslog
: Write error messages tosyslog
on systems that support the logger program.--skip-syslog
: Do not write error messages tosyslog
. Messages are written to the default error log file (
in the data directory), or to a named file if thehost_name
.err--log-error
option is given.
If none of these options is given, the default is
--skip-syslog
.
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
.
Controlling mysqld logging from
mysqld_safe is deprecated. Use the server's
native syslog
support instead. For more
information, see Section 5.4.2.7, “Error Logging to the System Log”.
Document created the 26/06/2006, last modified the 26/10/2018
Source of the printed document:https://www.gaudry.be/en/mysql-rf-mysqld-safe.html
The infobrol is a personal site whose content is my sole responsibility. The text is available under CreativeCommons license (BY-NC-SA). More info on the terms of use and the author.
References
These references and links indicate documents consulted during the writing of this page, or which may provide additional information, but the authors of these sources can not be held responsible for the content of this page.
The author This site is solely responsible for the way in which the various concepts, and the freedoms that are taken with the reference works, are presented here. Remember that you must cross multiple source information to reduce the risk of errors.