Most MySQL programs can read startup options from option files (also sometimes called configuration files). Option files provide a convenient way to specify commonly used options so that they need not be entered on the command line each time you run a program. For the MySQL server, MySQL provides a number of preconfigured option files.
To determine whether a program reads option files, invoke it with
--help option. (For
--help.) If the program reads
option files, the help message indicates which files it looks for
and which option groups it recognizes.
Option files used with MySQL Cluster programs are covered in Section 18.3, “Configuration of MySQL Cluster NDB 7.2”.
On Windows, MySQL programs read startup options from the following files, in the specified order (top items are used first).
|The file specified with
%PROGRAMDATA% represents the file system
directory that contains application data for all users on the
host. This path defaults to
Microsoft Windows Vista and greater, and
Settings\All Users\Application Data on older versions of
%WINDIR% represents the location of your
Windows directory. This is commonly
C:\WINDOWS. You can determine its exact
location from the value of the
environment variable using the following command:
INSTALLDIR represents the MySQL
installation directory. This is typically
PROGRAMDIR represents the programs
Program Files on
English-language versions of Windows), when MySQL 5.5
has been installed using the installation and configuration
wizards. See Section 2.3.3, “Installing MySQL on Microsoft Windows Using MySQL Installer”.
On Unix, Linux and Mac OS X, MySQL programs read startup options from the following files, in the specified order (top items are used first).
|The file specified with
~ represents the current user's home
directory (the value of
SYSCONFDIR represents the directory
specified with the
to CMake when MySQL was built. By default, this
etc directory located under the
compiled-in installation directory.
MYSQL_HOME is an environment variable
containing the path to the directory in which the server-specific
my.cnf file resides. If
MYSQL_HOME is not set and you start the server
using the mysqld_safe program,
mysqld_safe attempts to set
MYSQL_HOME as follows:
DATADIR represent the path names of
the MySQL base directory and data directory, respectively.
If there is a
my.cnf file in
DATADIR but not in
MYSQL_HOME is not set and
there is no
my.cnf file in
In MySQL 5.5, use of
DATADIR as the location for
my.cnf is deprecated.
/usr/local/mysql/data for a binary
/usr/local/var for a source
installation. Note that this is the data directory location that
was specified at configuration time, not the one specified with
--datadir option when
mysqld starts. Use of
--datadir at runtime has no effect
on where the server looks for option files, because it looks for
them before processing any options.
MySQL looks for option files in the order just described and reads any that exist. If an option file that you want to use does not exist, create it with a plain text editor.
If multiple instances of a given option are found, the last
instance takes precedence. There is one exception: For
mysqld, the first instance
--user option is used as a
security precaution, to prevent a user specified in an option file
from being overridden on the command line.
On Unix platforms, MySQL ignores configuration files that are world-writable. This is intentional as a security measure.
Any long option that may be given on the command line when running
a MySQL program can be given in an option file as well. To get the
list of available options for a program, run it with the
The syntax for specifying options in an option file is similar to
command-line syntax (see Section 4.2.4, “Using Options on the Command Line”).
However, in an option file, you omit the leading two dashes from
the option name and you specify only one option per line. For
--host=localhost on the command line should be
host=localhost on separate lines in an option
file. To specify an option of the form
--loose- in an
option file, write it as
Empty lines in option files are ignored. Nonempty lines can take any of the following forms:
Comment lines start with “
#” comment can start in the
middle of a line as well.
group is the name of the program or
group for which you want to set options. After a group line,
any option-setting lines apply to the named group until the
end of the option file or another group line is given. Option
group names are not case sensitive.
This is equivalent to
-- on the
This is equivalent to
on the command line. In an option file, you can have spaces
around the “
something that is not true on the command line. You can
optionally enclose the value within single quotation marks or
double quotation marks, which is useful if the value contains
#” comment character.
Leading and trailing spaces are automatically deleted from option names and values.
You can use the escape sequences
\s” in option values to represent
the backspace, tab, newline, carriage return, backslash, and space
characters. The escaping rules in option files are:
If a backslash is followed by a valid escape sequence
character, the sequence is converted to the character
represented by the sequence. For example,
\s” is converted to a space.
If a backslash is not followed by a valid escape sequence
character, it remains unchanged. For example,
\S” is retained as is.
The preceding rules mean that a literal backslash can be given as
\\”, or as
\” if it is not followed by a
valid escape sequence character.
The rules for escape sequences in option files differ slightly
from the rules for escape sequences in string literals in SQL
statements. In the latter context, if
x” is not a valid escape
x” rather than
See Section 9.1.1, “String Literals”.
The escaping rules for option file values are especially pertinent
for Windows path names, which use
\” as a path name separator. A
separator in a Windows path name must be written as
\\” if it is followed by an
escape sequence character. It can be written as
\” if it is not. Alternatively,
/” may be used in Windows path
names and will be treated as “
Suppose that you want to specify a base directory of
C:\Program Files\MySQL\MySQL Server
5.5 in an option file. This can be done
several ways. Some examples:
basedir="C:\Program Files\MySQL\MySQL Server 5.5" basedir="C:\\Program Files\\MySQL\\MySQL Server 5.5" basedir="C:/Program Files/MySQL/MySQL Server 5.5" basedir=C:\\Program\sFiles\\MySQL\\MySQL\sServer\s5.5
If an option group name is the same as a program name, options in
the group apply specifically to that program. For example, the
apply to the mysqld server and the
mysql client program, respectively.
[client] option group is read by all client
programs (but not by
mysqld). This enables you to specify options
that apply to all clients. For example,
[client] is the perfect group to use to specify
the password that you use to connect to the server. (But make sure
that the option file is readable and writable only by yourself, so
that other people cannot find out your password.) Be sure not to
put an option in the
[client] group unless it
is recognized by all client programs that you
use. Programs that do not understand the option quit after
displaying an error message if you try to run them.
Here is a typical global option file:
[client] port=3306 socket=/tmp/mysql.sock [mysqld] port=3306 socket=/tmp/mysql.sock key_buffer_size=16M max_allowed_packet=8M [mysqldump] quick
Here is a typical user option file:
[client] # The following password will be sent to all standard MySQL clients password="my_password" [mysql] no-auto-rehash connect_timeout=2 [mysqlhotcopy] interactive-timeout
If you want to create option groups that should be read by
mysqld servers from a specific MySQL release
series only, you can do this by using groups with names of
[mysqld-5.5], and so forth. The
following group indicates that the
should be used only by MySQL servers with 5.5.x
It is possible to use
!include directives in
option files to include other option files and
!includedir to search specific directories for
option files. For example, to include the
/home/mydir/myopt.cnf file, use the following
To search the
/home/mydir directory and read
option files found there, use this directive:
There is no guarantee about the order in which the option files in the directory will be read.
Currently, any files to be found and included using the
!includedir directive on Unix operating
systems must have file names ending in
.cnf. On Windows, this directive checks for
files with the
Write the contents of an included option file like any other
option file. That is, it should contain groups of options, each
preceded by a
[ line that
indicates the program to which the options apply.
While an included file is being processed, only those options in
groups that the current program is looking for are used. Other
groups are ignored. Suppose that a
file contains this line:
And suppose that
[mysqladmin] force [mysqld] key_buffer_size=16M
my.cnf is processed by
mysqld, only the
/home/mydir/myopt.cnf is used. If
the file is processed by mysqladmin, only the
[mysqladmin] group is used. If the file is
processed by any other program, no options in
/home/mydir/myopt.cnf are used.
!includedir directive is processed
similarly except that all option files in the named directory are