The mysqld_safe
startup script is in MariaDB distributions on Linux and Unix. It is a wrapper that starts mysqld
with some extra safety features. For example, if mysqld_safe
notices that mysqld
has crashed, then mysqld_safe
will automatically restart mysqld
.
mysqld_safe
is the recommended way to start mysqld
on Linux and Unix distributions that do not support systemd
. Additionally, the mysql.server
init script used by sysVinit
starts mysqld
with mysqld_safe
by default.
From MariaDB 10.4.6, mariadbd-safe
is a symlink to mysqld_safe
.
The command to use mysqld_safe
and the general syntax is:
mysqld_safe [ --defaults-file | --defaults-extra-file ] <options> <mysqld_options>
Many of the options supported by mysqld_safe
are identical to options supported by mysqld
. If an unknown option is provided to mysqld_safe
on the command-line, then it is passed to mysqld
.
mysqld_safe
supports the following options:
Option | Description |
---|---|
--help |
Display a help message and exit. |
--autoclose |
(NetWare only) On NetWare, mysqld_safe provides a screen presence. When you unload (shut down) the mysqld_safe NLM, the screen does not by default go away. Instead, it prompts for user input: NLM has terminated; Press any key to close the screen . If you want NetWare to close the screen automatically instead, use the --autoclose option to mysqld_safe. |
--basedir=path |
The path to the MariaDB installation directory. |
--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. |
--crash-script=file |
Script to call in the event of mysqld crashing. |
--datadir=path |
The path to the data directory. |
--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. |
--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. |
--flush-caches |
Flush and purge buffers/caches before starting the server. |
--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. |
--log-error=file_name |
Write the error log to the given file. |
--malloc-lib=lib |
Preload shared library lib if available. See debugging MariaDB for an example. |
--mysqld=prog_nam |
The name of the server program (in the ledir directory) that you want to start. This option is needed if you use the MariaDB 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. |
--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 mysqld-debug program in the ledir directory. If the argument to --mysqld-version is empty, mysqld_safe uses mysqld in the ledir directory. |
--nice=priority |
Use the nice program to set the server´s scheduling priority to the given value. |
--no-auto-restart |
Exit after starting mysqld. |
--no-defaults |
Do not read any option files. This must be the first option on the command line if it is used. |
--no-watch |
Exit after starting mysqld. |
--numa-interleave |
Run mysqld with its memory interleaved on all NUMA nodes. |
--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 properly. |
--pid-file=file_name |
The path name of the process ID file. |
--plugin-dir=dir_name , |
Directory for client-side plugins. |
--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. |
--skip-kill-mysqld |
Do not try to kill stray mysqld processes at startup. This option works only on Linux. |
--socket=path |
The Unix socket file that the server should use when listening for local connections. |
--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 error log file. |
--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 . |
--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. Also see Time Zones. |
--user={user_name or 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 MariaDB user listed in the grant tables.) |
In addition to reading options from the command-line, mysqld_safe
can also read options from option files. If an unknown option is provided to mysqld_safe
in an option file, then it is ignored.
The following options relate to how MariaDB command-line tools handles option files. They must be given as the first argument on the command-line:
Option | Description |
---|---|
--print-defaults |
Print the program argument list and exit. |
--no-defaults |
Don't read default options from any option file. |
--defaults-file=# |
Only read default options from the given file #. |
--defaults-extra-file=# |
Read this file after the global files are read. |
mysqld_safe
reads options from the following option groups from option files:
Group | Description |
---|---|
[mysqld_safe] |
Options read by mysqld_safe , which includes both MariaDB Server and MySQL Server. |
[mariadb_safe] |
Options read by mysqld_safe from MariaDB Server. |
[safe_mysqld] |
Options read by mysqld_safe , which includes both MariaDB Server and MySQL Server. |
The [safe_mysqld]
option group is primarily supported for backward compatibility. You should rename such option groups to [mysqld_safe]
in MariaDB installations to prevent breakage in the future if this compatibility is removed.
mysqld_safe
also reads options from the following server option groups from option files:
Group | Description |
---|---|
[mysqld] |
Options read by mysqld , which includes both MariaDB Server and MySQL Server. |
[server] |
Options read by MariaDB Server. |
[mysqld-X.Y] |
Options read by a specific version of mysqld , which includes both MariaDB Server and MySQL Server. For example, [mysqld-5.5] . |
[mariadb] |
Options read by MariaDB Server. |
[mariadb-X.Y] |
Options read by a specific version of MariaDB Server. |
[client-server] |
Options read by all MariaDB client programs and the MariaDB Server. This is useful for options like socket and port, which is common between the server and the clients. |
[galera] |
Options read by a galera-capable MariaDB Server. Available on systems compiled with Galera support. |
For example, if you specify the log_error
option in a server option group in an option file, like this:
[mariadb] log_error=error.log
Then mysqld_safe
will also use this value for its own --log-error
option:
When using mysqld_safe
, the system's open files limit can be changed by providing the --open-files-limit
option either on the command-line or in an option file. For example:
[mysqld_safe] open_files_limit=4294967295
The option value is passed to ulimit -n
. Note that you need to start mysqld_safe
as root for this to work properly. However, you can't currently set this to unlimited
. See MDEV-18410 about that.
When mysqld_safe
starts mysqld
, it also uses this option to set the value of the open_files_limit
system variable for mysqld
.
When using mysqld_safe
, if you would like to enable core dumps, the system's core file size limit can be changed by providing the --core-file-size
option either on the command-line or in an option file. For example:
[mysqld_safe] core_file_size=unlimited
The option value is passed to ulimit -c
. Note that you need to start mysqld_safe
as root for this to work properly.
When using mysqld_safe
, if you would like to redirect the error log to the syslog, then that can easily be done by using the --syslog
option. mysqld_safe
redirects two types of log messages to the syslog--its own log messages, and log messages for mysqld
.
mysqld_safe
configures its own log messages to go to the daemon
syslog facility. The log level for these messages is either notice
or error
, depending on the specific type of log message. The default tag is mysqld_safe
. mysqld_safe
also configures the log messages for mysqld
to go to the daemon
syslog facility. The log level for these messages is error
. The default tag is mysqld
. Sometimes it can be helpful to add a suffix to the syslog tag, such as if you are running multiple instances of MariaDB on the same host. To add a suffix to each syslog tag, use the --syslog-tag
option.
By default, mysqld_safe
tries to start an executable named mysqld
.
You can also specify another executable for mysqld_safe
to start instead of mysqld
by providing the --mysqld
or --mysqld-version
options either on the command-line or in an option file.
By default, it will look for mysqld
in the following locations in the following order:
$BASEDIR/libexec/mysqld
$BASEDIR/sbin/mysqld
$BASEDIR/bin/mysqld
$PWD/bin/mysqld
$PWD/libexec/mysqld
$PWD/sbin/mysqld
@libexecdir@/mysql
Where $BASEDIR
is set by the --basedir
option, $PWD
is the current working directory where mysqld_safe
was invoked, and @libexecdir@
is set at compile-time by the INSTALL_BINDIR
option for cmake
.
You can also specify where the executable is located by providing the --ledir
option either on the command-line or in an option file.
By default, mysqld_safe
will look for the datadir
in the following locations in the following order:
$BASEDIR/data/mysql
$BASEDIR/data
$BASEDIR/var/mysql
$BASEDIR/var
@localstatedir@
Where $BASEDIR
is set by the --basedir
option, and @localstatedir@
is set at compile-time by the INSTALL_MYSQLDATADIR
option for cmake
.
You can also specify where the datadir
is located by providing the --datadir
option either on the command-line or in an option file.
When you use mysqld_safe
to start mysqld
, mysqld_safe
logs to the same destination as mysqld
.
mysqld_safe
has several log-related options:
--syslog
: Write error messages to syslog on systems that support the logger program. --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. --log-error=file_name
: Write error messages to the named error file. If none of these options is provided, then the default is --skip-syslog
.
If --syslog
and --log-error
are both provided, then a warning is issued and --log-error
takes precedence.
mysqld_safe
also writes notices to stdout
and errors to stderr
.
mysqld_safe
is a sh
script, so if you need to change its behavior, then it can easily be edited. However, you should not normally edit the script. A lot of behavior can be changed by providing options either on the command-line or in an option file.
If you do edit mysqld_safe
, then you should be aware of the fact that a package upgrade can overwrite your changes. If you would like to preserve your changes, be sure to have a backup.
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:
Changed limits: max_open_files: 1024 (requested 5000)"
© 2019 MariaDB
Licensed under the Creative Commons Attribution 3.0 Unported License and the GNU Free Documentation License.
https://mariadb.com/kb/en/mysqld_safe/