mysqld_safe
MYSQLD_SAFE(1) MySQL Database System MYSQLD_SAFE(1)
NAME
mysqld_safe - MySQL server startup script
SYNOPSIS
mysqld_safe options
DESCRIPTION
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.
Note
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".
One implication of the non-use of mysqld_safe on platforms that use
systemd for server management is that use of [mysqld_safe] or
[safe_mysqld] sections in option files is not supported and might
lead to unexpected behavior.
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 7.1.7, "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 6.2.2.2, "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 finds and uses 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 6.2.2.2, "Using Option Files".
o --help
+--------------------+--------+
|Command-Line Format | --help |
+--------------------+--------+
Display a help message and exit.
o --basedir=dir_name
+--------------------+--------------------+
|Command-Line Format | --basedir=dir_name |
+--------------------+--------------------+
|Type | Directory name |
+--------------------+--------------------+
The path to the MySQL installation directory.
o --core-file-size=size
+--------------------+-----------------------+
|Command-Line Format | --core-file-size=size |
+--------------------+-----------------------+
|Type | String |
+--------------------+-----------------------+
The size of the core file that mysqld should be able to create. The
option value is passed to ulimit -c.
Note
The 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 17.8.3.7, "Excluding
Buffer Pool Pages from Core Files".
o --datadir=dir_name
+--------------------+--------------------+
|Command-Line Format | --datadir=dir_name |
+--------------------+--------------------+
|Type | Directory name |
+--------------------+--------------------+
The path to the data directory.
o --defaults-extra-file=file_name
+--------------------+-------------------+
|Command-Line Format | --defaults-extra- |
| | file=file_name |
+--------------------+-------------------+
|Type | 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 exits
with an error. If file_name is not an absolute path name, it is
interpreted relative to the current directory. 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 6.2.2.3, "Command-Line Options that Affect
Option-File Handling".
o --defaults-file=file_name
+--------------------+---------------------------+
|Command-Line Format | --defaults-file=file_name |
+--------------------+---------------------------+
|Type | File name |
+--------------------+---------------------------+
Use only the given option file. If the file does not exist or is
otherwise inaccessible, the server exits with an error. If
file_name is not an absolute path name, it is interpreted relative
to the current directory. 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 6.2.2.3, "Command-Line Options that Affect
Option-File Handling".
o --ledir=dir_name
+--------------------+------------------+
|Command-Line Format | --ledir=dir_name |
+--------------------+------------------+
|Type | Directory name |
+--------------------+------------------+
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".
o --log-error=file_name
+--------------------+-----------------------+
|Command-Line Format | --log-error=file_name |
+--------------------+-----------------------+
|Type | File name |
+--------------------+-----------------------+
Write the error log to the given file. See Section 7.4.2, "The
Error Log".
o --mysqld-safe-log-timestamps
+--------------------+--------------------+
|Command-Line Format | --mysqld-safe-log- |
| | timestamps=type |
+--------------------+--------------------+
|Type | Enumeration |
+--------------------+--------------------+
|Default Value | utc |
+--------------------+--------------------+
|Valid Values | |
| | system |
| | |
| | hyphen |
| | |
| | legacy |
+--------------------+--------------------+
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.
o UTC, utc
ISO 8601 UTC format (same as --log_timestamps=UTC for the
server). This is the default.
o SYSTEM, system
ISO 8601 local time format (same as --log_timestamps=SYSTEM for
the server).
o HYPHEN, hyphen
YY-MM-DD h:mm:ss format, as in mysqld_safe for MySQL 5.6.
o LEGACY, legacy
YYMMDD hh:mm:ss format, as in mysqld_safe prior to MySQL 5.6.
o --malloc-lib=[lib_name]
+--------------------+-------------------------+
|Command-Line Format | --malloc-lib=[lib-name] |
+--------------------+-------------------------+
|Type | String |
+--------------------+-------------------------+
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 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 and no attempt is
made to use tcmalloc.
o Prior to MySQL 8.0.21, if the option is given as
--malloc-lib=tcmalloc, mysqld_safe looks for a tcmalloc library
in /usr/lib. 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.
As of MySQL 8.0.21, tcmalloc is not a permitted value for the
--malloc-lib option.
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.
Note
On 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 a tcmalloc package is installed in /usr/lib by
adding these lines to the my.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
o --mysqld=prog_name
+--------------------+--------------------+
|Command-Line Format | --mysqld=file_name |
+--------------------+--------------------+
|Type | File 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.
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".
o --mysqld-version=suffix
+--------------------+-------------------------+
|Command-Line Format | --mysqld-version=suffix |
+--------------------+-------------------------+
|Type | String |
+--------------------+-------------------------+
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 the ledir directory.
If the argument to --mysqld-version is empty, mysqld_safe uses
mysqld in the ledir 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".
o --nice=priority
+--------------------+-----------------+
|Command-Line Format | --nice=priority |
+--------------------+-----------------+
|Type | Numeric |
+--------------------+-----------------+
Use the nice program to set the server's scheduling priority to the
given value.
o --no-defaults
+--------------------+---------------+
|Command-Line Format | --no-defaults |
+--------------------+---------------+
|Type | String |
+--------------------+---------------+
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 6.2.2.3, "Command-Line Options that Affect
Option-File Handling".
o --open-files-limit=count
+--------------------+--------------------------+
|Command-Line Format | --open-files-limit=count |
+--------------------+--------------------------+
|Type | String |
+--------------------+--------------------------+
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 root for this to function
properly.
o --pid-file=file_name
+--------------------+----------------------+
|Command-Line Format | --pid-file=file_name |
+--------------------+----------------------+
|Type | File name |
+--------------------+----------------------+
The path name that mysqld should use for its process ID file.
o --plugin-dir=dir_name
+--------------------+-----------------------+
|Command-Line Format | --plugin-dir=dir_name |
+--------------------+-----------------------+
|Type | Directory name |
+--------------------+-----------------------+
The path name of the plugin directory.
o --port=port_num
+--------------------+---------------+
|Command-Line Format | --port=number |
+--------------------+---------------+
|Type | Numeric |
+--------------------+---------------+
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.
o --skip-kill-mysqld
+--------------------+--------------------+
|Command-Line Format | --skip-kill-mysqld |
+--------------------+--------------------+
Do not try to kill stray mysqld processes at startup. This option
works only on Linux.
o --socket=path
+--------------------+--------------------+
|Command-Line Format | --socket=file_name |
+--------------------+--------------------+
|Type | File name |
+--------------------+--------------------+
The Unix socket file that the server should use when listening for
local connections.
o --syslog, --skip-syslog
+--------------------+----------+
|Command-Line Format | --syslog |
+--------------------+----------+
|Deprecated | Yes |
+--------------------+----------+
+--------------------+---------------+
|Command-Line Format | --skip-syslog |
+--------------------+---------------+
|Deprecated | Yes |
+--------------------+---------------+
--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 error log file.
When syslog is used for error logging, the daemon.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 7.4.2.8, "Error Logging to the System Log". To control the
facility, use the server log_syslog_facility system variable.
o --syslog-tag=tag
+--------------------+------------------+
|Command-Line Format | --syslog-tag=tag |
+--------------------+------------------+
|Deprecated | Yes |
+--------------------+------------------+
For logging to syslog, messages from mysqld_safe and mysqld are
written with identifiers of mysqld_safe and mysqld, respectively.
To specify a suffix for the identifiers, use --syslog-tag=tag,
which modifies the identifiers to be mysqld_safe-tag and
mysqld-tag.
Using this option to control mysqld logging is deprecated. Use the
server log_syslog_tag system variable instead. See Section 7.4.2.8,
"Error Logging to the System Log".
o --timezone=timezone
+--------------------+---------------------+
|Command-Line Format | --timezone=timezone |
+--------------------+---------------------+
|Type | String |
+--------------------+---------------------+
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}
+--------------------+----------------------------+
|Command-Line Format | --user={user_name|user_id} |
+--------------------+----------------------------+
|Type | String |
+--------------------+----------------------------+
|Type | Numeric |
+--------------------+----------------------------+
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 is not used.
For example, this command does 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 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:
cd mysql_installation_directory
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:
o --log-error=file_name: Write error messages to the named error
file.
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.
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.
Note
Controlling mysqld logging from mysqld_safe is deprecated. Use the
server's native syslog support instead. For more information, see
Section 7.4.2.8, "Error Logging to the System Log".
COPYRIGHT
Copyright (C) 1997, 2024, Oracle and/or its affiliates.
This documentation is free software; you can redistribute it and/or
modify it only under the terms of the GNU General Public License as
published by the Free Software Foundation; version 2 of the License.
This documentation is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License along
with the program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA or see
http://www.gnu.org/licenses/.
SEE ALSO
For more information, please refer to the MySQL Reference Manual, which
may already be installed locally and which is also available online at
http://dev.mysql.com/doc/.
AUTHOR
Oracle Corporation (http://dev.mysql.com/).
MySQL 8.0 12/13/2024 MYSQLD_SAFE(1)
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