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.
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]
group of an option file. See
Section 4.2.3.3, “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, although you
should rename such sections to [mysqld_safe]
in MySQL 5.5 installations.
mysqld_safe supports the following options. It also reads option files and supports the options for processing them described at Section 4.2.3.3.1, “Command-Line Options that Affect Option-File Handling”.
Table 4.1. mysqld_safe
Options
Format | Config File | Description | Introduction | Deprecated | Removed |
---|---|---|---|---|---|
--autoclose | autoclose | On NetWare, mysqld_safe provides a screen presence | |||
--basedir=path | basedir | The path to the MySQL installation directory | |||
--core-file-size=size | core-file-size | The size of the core file that mysqld should be able to create | |||
--datadir=path | datadir | The path to the data directory | |||
--defaults-extra-file=path | defaults-extra-file | The name of an option file to be read in addition to the usual option files | |||
--defaults-file=file_name | defaults-file | The name of an option file to be read instead of the usual option files | |||
--help | Display a help message and exit | ||||
--ledir=path | ledir | Use this option to indicate the path name to the directory where the server is located | |||
--log-error=file_name | log-error | Write the error log to the given file | |||
--malloc-lib=[lib-name] | malloc-lib | Alternative malloc library to use for mysqld | |||
--mysqld=prog_name | mysqld | The name of the server program (in the ledir directory) that you want to start | |||
--mysqld-version=suffix | mysqld-version | This option is similar to the --mysqld option, but you specify only the suffix for the server program name | |||
--nice=priority | nice | Use the nice program to set the server's scheduling priority to the given value | |||
--no-defaults | no-defaults | Do not read any option files | |||
--open-files-limit=count | open-files-limit | The number of files that mysqld should be able to open | |||
--pid-file | pid-file | The path name of the process ID file | |||
--port=number | port | The port number that the server should use when listening for TCP/IP connections | |||
--skip-kill-mysqld | skip-kill-mysqld | Do not try to kill stray mysqld processes | |||
--skip-syslog | skip-syslog | Do not write error messages to syslog; use error log file | |||
--socket=path | socket | The Unix socket file that the server should use when listening for local connections | |||
--syslog | syslog | Write error messages to syslog | |||
--timezone=timezone | timezone | Set the TZ time zone environment variable to the given option value | |||
--user={user_name|user_id} | user | Run the mysqld server as the user having the name user_name or the numeric user ID user_id |
Display a help message and exit.
(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.
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 library to use for memory allocation instead
of the system malloc()
library. Any
library can be used by specifying its path name, but there
is a shortcut form to enable use of the
tcmalloc
library that is shipped with
binary MySQL distributions for Linux in MySQL
5.5.
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:
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
.
If the option is given as
--malloc-lib=tcmalloc
,
mysqld_safe looks for a
tcmalloc
library in
/usr/lib
and then in the MySQL
pkglibdir
location (for example,
/usr/local/mysql/lib
or whatever is
appropriate). 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.
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.
Linux users can use the
libtcmalloc_minimal.so
included in
binary packages by adding these lines to the
my.cnf
file:
[mysqld_safe] malloc-lib=tcmalloc
Those lines also suffice for users on any platform who have
installed a tcmalloc
package in
/usr/lib
. 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 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 is used.
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 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 to syslog
on systems
that support the logger program.
--skip-syslog
suppresses the use of
syslog
; messages are written to an error
log file.
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=
,
which modifies the tags to be
tag
mysqld_safe-
and
tag
mysqld-
.
tag
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 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:
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).
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
shell>mysql_installation_directory
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.
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
(
in the data directory), or to a named file if the
host_name
.err--log-error
option is
given.
--log-error=
:
Write error messages to the named error file.
file_name
If none of these options is given, the default is
--skip-syslog
.
If --syslog
and
--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 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:
Runs a number of system and option checks.
Runs a check on MyISAM
tables.
Provides a screen presence for the MySQL server.
Starts mysqld, monitors it, and restarts it if it terminates in error.
Sends error messages from mysqld to the
file in the data directory.
host_name
.err
Sends mysqld_safe screen output to the
file in the data directory.
host_name
.safe
User Comments
If you invoke mysql_safe from the default /etc/init.d/mysql script, beware of interference from SELinux. You may run into a problem where mysql_safe terminates immediately and causes the start operation to fail. If so, try turning off SELinux and see if it makes the problem go away.
Add your own comment.