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. Descriptions of error logging are 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-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.
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.
mysqld_safe reads all options from the [mysqld],
[mysqld_safe] and [mariadb_safe] sections in option files. For example, if
you specify a [mysqld] section like this, mysqld_safe will
find and use the
For backward compatibility, mysqld_safe also reads [safe_mysqld] sections, although you should rename such sections to [mysqld_safe] in MariaDB installations.
mysqld_safe supports the following options:
|Display a help message and exit.|
|(NetWare only) On NetWare, |
|The path to the MariaDB installation directory.|
|The size of the core file that mysqld should be able to create. The option value is passed to ulimit -c.|
|Script to call in the event of mysqld crashing.|
|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.|
|Flush and purge buffers/caches before starting the server.|
|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.|
|Preload shared library lib if available.|
|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 |
|This option is similar to the |
|Use the nice program to set the server´s scheduling priority to the given value.|
|Exit after starting mysqld.|
|Do not read any option files. This must be the first option on the command line if it is used.|
|Exit after starting mysqld.|
|Run mysqld with its memory interleaved on all NUMA nodes.|
|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.|
|The path name of the process ID file.|
|Directory for client-side plugins.|
|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.|
|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.|
|For logging to syslog, messages from |
|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.|
|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.)|
If you execute mysqld_safe with the
--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 MariaDB, even though these types of distributions typically install the server in slightly different locations. 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 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 MariaDB 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/var. The actual locations are determined from the values configured into the distribution at the time it was built. They should be correct if MariaDB 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 MariaDB anywhere, as long as you run mysqld_safe from the MariaDB installation directory:
shell> cd mysql_installation_directory shell> bin/mysqld_safe &
If mysqld_safe fails, even when invoked from the MariaDB
installation directory, you can specify the
--datadir options to indicate the directories in which the
server and databases are located on your system.
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:
--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-erroroption is given.
--log-error=file_name: Write error messages to the named error file.
If none of these options is given, the default is
--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 MariaDB in the future, so you should make a copy of your edited version that you can reinstall.
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:
- Runs a number of system and option checks.
- Runs a check on MyISAM tables.
- Provides a screen presence for the MariaDB server.
- Starts mysqld, monitors it, and restarts it if it terminates in error.
- Sends error messages from mysqld to the host_name.err file in the data directory.
- Sends mysqld_safe screen output to the host_name.safe file in the data directory.