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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 they need not be entered on the command line each time you run a program. Option file capability is available from MySQL 3.22 on.
The following programs support option files: mysql
,
mysqladmin
, mysqld
, mysqld_safe
, mysql.server
,
mysqldump
, mysqlimport
, mysqlshow
, mysqlcheck
,
mysqlhotcopy
,
myisamchk
, and myisampack
.
On Windows, MySQL programs read startup options from the following files:
Filename | Purpose |
windows-dir\my.ini | Global options |
C:\my.cnf | Global options |
windows-dir
represents the location of your Windows directory.
This is commonly `C:\Windows' or `C:\WinNT'. Check the value of the
WINDIR
environment vairable to see where this directory is located on
your system.
On Unix, MySQL programs read startup options from the following files:
Filename | Purpose |
/etc/my.cnf | Global options |
DATADIR/my.cnf | Server-specific options |
defaults-extra-file | The file specified with --defaults-extra-file=path , if any |
~/.my.cnf | User-specific options |
DATADIR
represents the location of the MySQL data directory. Typically
this is `/usr/local/mysql/data' for a binary installation or
`/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
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
command-line arguments.
MySQL looks for option files in the order listed above and reads any that exist. If multiple option files exist, an option specified in a file read later takes precedence over the same option specified in a file read earlier.
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 --help
option.
The syntax for
specifying options in an option file is similar to command-line syntax, except
that you omit the leading two dashes. For example, --quick
or
--host=localhost
on the command line are specified as quick
or
host=localhost
in an option file.
To specify an option of the form --loose-opt_name
in an option file, write it as loose-opt_name
.
Empty lines in option files are ignored. Non-empty lines can take any of the following forms:
#comment
;comment
[group]
group
is the name of the program or group for which you want to set
options. After a group line, any option
or set-variable
lines
apply to the named group until the end of the option file or another group
line is given.
opt_name
--opt_name
on the command-line.
opt_name=value
--opt_name=value
on the command-line.
In an option file, you can have spaces around the `=' character,
something that is not true on the command line.
As of
MySQL 4.0.16, you can quote the value with double quotes or single quotes.
This is useful if the value contains a comment character or whitespace.
set-variable = var_name=value
var_name
to the given value.
This is equivalent to --set-variable=var_name=value
on the
command-line.
Spaces are allowed around the first `=' character but not around
the second.
This syntax is deprecated as of MySQL 4.0.
See 4.3.4 Using Options to Set Program Variables for more information on setting program variables.
Note that for options and values, all leading and trailing blanks are automatically deleted. You may use the escape sequences `\b', `\t', `\n', `\r', `\\', and `\s' in option values to represent the backspace, tab, newline, carriage return, and space characters.
On Windows, if an option value represents a pathname, you should specify the value using `/' rather than `\' as the pathname separator. If you use `\', you must double it as `\\', because `\' is the escape character in MySQL.
If an option group name is the same as a program name, options in the group apply specifically to that program.
The [client]
option group is read by all client programs
(but not by mysqld
). This allows you to specify options that apply to
every client. For example, [client]
is the perfect group to use
to specify the password that you use to connect to the server. (But make
sure 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.
As of MySQL 4.0.14,
if you want to create options that should only be read by one specific
mysqld
server release series, you can do this with [mysqld-4.0]
,
[mysqld-4.1]
, and so forth:
[mysqld-4.0] new |
The above new
option will be used only with MySQL server versions 4.0.x.
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=1M [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 set-variable = connect_timeout=2 [mysqlhotcopy] interactive-timeout |
If you have a source distribution, you will find sample option files named `my-xxxx.cnf' in the `support-files' directory. If you have a binary distribution, look in the `support-files' directory under your MySQL installation directory (typically `C:\mysql' on Windows or `/usr/local/mysql' on Unix). Currently there are sample option files for small, medium, large, and very large systems. To experiment with one of these files, copy it to `C:\my.cnf' on Windows or to `.my.cnf' in your home directory on Unix.
All MySQL programs that support option files support the following command-line options:
--no-defaults
--print-defaults
--defaults-file=path_name
path_name
is the full pathname
to the file.
--defaults-extra-file=path_name
path_name
is the full pathname to the file.
Note that to work properly, each of these options must immediately
follow the command name on the command line, with the exception
that --print-defaults
may be used immediately after
--defaults-file
or --defaults-extra-file
.
In shell scripts, you can use the my_print_defaults
program to parse the
option files. The following example shows the output that
my_print_defaults
might produce when asked to show the options found in
the [client]
and [mysql]
groups:
shell> my_print_defaults client mysql --port=3306 --socket=/tmp/mysql.sock --no-auto-rehash |
Note for developers: Option file handling is implemented in the C client library simply by processing all matching options (that is, options in the appropriate group) before any command-line arguments. This works nicely for programs that use the last instance of an option that is specified multiple times. If you have a C or C++ program that handles multiply specified options this way but doesn't read option files, you need add only two lines to give it that capability. Check the source code of any of the standard MySQL clients to see how to do this.
Several other language interfaces to MySQL are based on the C client library, and some of them provide a way to access option file contents. These include Perl and Python. See the documentation for your preferred interface for details.
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