1.5 Specifying Connection Parameters by Using Option Files
1.5.1 Problem
You don't want to type
connection parameters on the command line every time you invoke
mysql.
1.5.2 Solution
Put the parameters in an option file.
1.5.3 Discussion
To avoid entering connection parameters manually, put them in an
option file for mysql to read automatically. Under
Unix, your personal option file is named
.my.cnf in your home directory. There are also
site-wide option files that administrators can use to specify
parameters that apply globally to all users. You can use
/etc/my.cnf or the my.cnf
file in the MySQL server's data directory. Under
Windows, the option files you can use are
C:\my.cnf, the my.ini file
in your Windows system directory, or my.cnf in
the server's data directory.
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Windows may hide
filename extensions when
displaying files, so a file named my.cnf may
appear to be named just my. Your version of
Windows may allow you to disable extension-hiding. Alternatively,
issue a DIR command in a DOS window to see full
names.
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The following example illustrates the format used to write
MySQL option
files:
# general client program connection options
[client]
host=localhost
user=cbuser
password=cbpass
# options specific to the mysql program
[mysql]
no-auto-rehash
# specify pager for interactive mode
pager=/usr/bin/less
This format has the following general characteristics:
Lines are written in groups.
The first line of the group specifies the group name inside of square
brackets, and the remaining lines specify options associated with the
group. The example file just shown has a [client]
group and a [mysql] group. Within a group, option
lines are written in name=value format,
where name corresponds to an option name
(without leading dashes) and value is the
option's value. If an option
doesn't take any value (such as for the
no-auto-rehash option), the name is listed by
itself with no trailing =value part.
If you don't need some particular parameter, just
leave out the corresponding line. For example, if you normally
connect to the default host (localhost), you
don't need any host line. If your
MySQL username is the same as your operating system login name, you
can omit the user line.
In option files, only the long form of an
option is allowed. This is in contrast to command lines, where
options often can be specified using a short form or a long form. For
example, the hostname can be given using either -h
hostname or
--host=hostname
on the command line; in an option file, only
host=hostname is
allowed.
Options often are used for connection parameters (such as
host, user, and
password). However, the file can specify options
that have other purposes. The pager option shown
for the [mysql] group specifies the paging program
that mysql should use for displaying output in
interactive mode. It has nothing to do with how the program connects
to the server.
The usual group for specifying client connection parameters is
[client]. This group actually is used by all the
standard MySQL clients, so by creating an option file to use with
mysql, you make it easier to invoke other programs
such as mysqldump and
mysqladmin as well.
You can define multiple groups in an option file. A common convention
is for a program to look for parameters in the
[client] group and in the group named after the
program itself. This provides a convenient way to list general client
parameters that you want all client programs to use, but still be
able to specify options that apply only to a particular program. The
preceding sample option file illustrates this convention for the
mysql program, which gets general connection
parameters from the [client] group and also picks
up the no-auto-rehash and pager
options from the [mysql] group. (If you put the
mysql-specific options in the
[client] group, that will result in
"unknown option" errors for all
other programs that use the [client] group and
they won't run properly.)
If a parameter is specified multiple times in an option file, the
last value found takes precedence. This means that normally you
should list any program-specific groups after the
[client] group so that if there is any overlap in
the options set by the two groups, the more general options will be
overridden by the program-specific values.
Lines beginning with # or ;
characters are ignored as comments. Blank lines are ignored, too.
Option files must be plain text files. If you create an option file
with a word processor that uses some non-text format by default, be
sure to save the file explicitly as text. Windows users especially
should take note of this.
Options that specify file or directory pathnames should be written
using / as the pathname separator character, even
under Windows.
If you want to find out which options will be taken from option files
by mysql, use this command:
% mysql --print-defaults
You can also use the
my_print_defaults utility, which takes as arguments the
names of the option file groups that it should read. For example,
mysql looks in both the
[client] and [mysql] groups for
options, so you can check which values it will take from option files
like this:
% my_print_defaults client mysql
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