MYSQLD_SAFE(1) MySQL Database System MYSQLD_SAFE(1)
mysqld_safe - MySQL server startup script
mysqld_safe is the recommended way to start a mysqld server on Unix and NetWare.
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 and
NetWare-specific behaviors are given later in this section.
In MySQL 5.1.20 (only), the default error logging behavior with mysqld_safe is to
write errors to syslog on systems that support the logger program. This differs from
the default behavior of writing an error log file for other versions.
In 5.1.20, logging to syslog may fail to operate correctly in some cases; if so, use
--skip-syslog to use the default log file or --log-error=file_name to specify a log
file name explicitly.
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 5.1.2, "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] or [mariadb_safe] groups of
an option file. See Section 18.104.22.168, "Using Option Files".
mysqld_safe reads all options from the [mysqld], [server], [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 --log-error option:
For backward compatibility, mysqld_safe also reads [safe_mysqld] sections, although you
should rename such sections to [mysqld_safe] in MySQL 5.1 installations.
mysqld_safe supports the options in the following list. It also reads option files and
supports the options for processing them described at Section 22.214.171.124.1, "Command-Line
Options that Affect Option-File Handling".
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 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 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.
Use the nice program 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
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.
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
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.
o --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. These options were added in MySQL 5.1.20.
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. This
option was added in MySQL 5.1.21.
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 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 will not be used. For example, this command will not use the named option
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:
shell> cd mysql_installation_directory
shell> bin/mysqld_safe &
If mysqld_safe fails, even when invoked from the MySQL installation directory, you can
specify the --ledir and --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.
As of MySQL 5.1.20, there are several mysqld_safe options for controlling the destination
of these messages:
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.
o --log-error=file_name: Write error messages to the named error file.
If none of these options is given, the default is --skip-syslog.
In MySQL 5.1.20 only, the default is --syslog. This differs from logging behavior for
other versions of MySQL, for which the default is to write messages to the default
error log file.
If --syslog and --log-error are both given, a warning is issued and --log-error takes
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.
Before MySQL 5.1.20, error logging is controlled only with the --log-error option. If it
is given, messages go to the named error file. Otherwise, messages go to the default error
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 MySQL 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:
1. Runs a number of system and option checks.
2. Runs a check on MyISAM tables.
3. Provides a screen presence for the MySQL server.
4. Starts mysqld, monitors it, and restarts it if it terminates in error.
5. Sends error messages from mysqld to the host_name.err file in the data directory.
6. Sends mysqld_safe screen output to the host_name.safe file in the data directory.
Copyright 2007-2008 MySQL AB, 2008-2010 Sun Microsystems, Inc.
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.
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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/.
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/.
Sun Microsystems, Inc. (http://www.mysql.com/).
MySQL 5.1 04/06/2010 MYSQLD_SAFE(1)