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Table of Contents
This chapter provides a brief overview of the command-line programs provided by MySQL AB and discusses the general syntax for specifying options when you run these programs. Most programs have options that are specific to their own operation, but the option syntax is similar for all of them. Later chapters provide more detailed descriptions of individual programs, including which options they recognize.
MySQL AB also provides three GUI client programs for use with MySQL Server:
MySQL Administrator: This tool is used for administering MySQL servers, databases, tables, and user accounts.
MySQL Query Browser: This graphical tool is provided by MySQL AB for creating, executing, and optimizing queries on MySQL databases.
MySQL Migration Toolkit: This tool helps you migrate schemas and data from other relational database management systems for use with MySQL.
These GUI programs each have their own manuals that you can access at http://dev.mysql.com/doc/.
MySQL AB provides several types of programs:
The MySQL server and server startup scripts:
mysqld is the MySQL server.
mysqld_safe, mysql.server, and mysqld_multi are server startup scripts.
mysql_install_db initializes the data directory and the initial databases.
MySQL Instance Manager monitors and manages MySQL Server instances.
Chapter 5, Database Administration, discusses these programs further
Client programs that access the server:
mysql is a command-line client for executing SQL statements interactively or in batch mode.
mysqladmin is an administrative client.
mysqlcheck performs table maintenance operations.
mysqldump and mysqlhotcopy make database backups.
mysqlimport imports data files.
mysqlshow displays information about databases and tables.
Chapter 8, Client and Utility Programs, discusses these programs further
Utility programs that operate independently of the server:
myisamchk performs table maintenance operations.
myisampack produces compressed, read-only tables.
mysqlbinlog is a tool for processing binary log files.
perror displays the meaning of error codes.
Chapter 8, Client and Utility Programs, discusses these programs further
Most MySQL distributions include all of these programs, except for those programs that are platform-specific. (For example, the server startup scripts are not used on Windows.) The exception is that RPM distributions are more specialized. There is one RPM for the server, another for client programs, and so forth. If you appear to be missing one or more programs, see Chapter 2, Installing and Upgrading MySQL, for information on types of distributions and what they contain. It may be that you have a distribution that does not include all programs and you need to install something else.
To invoke a MySQL program from the command line (that is, from
your shell or command prompt), enter the program name followed by
any options or other arguments needed to instruct the program what
you want it to do. The following commands show some sample program
invocations. “shell>
”
represents the prompt for your command interpreter; it is not part
of what you type. The particular prompt you see depends on your
command interpreter. Typical prompts are $
for
sh or bash,
%
for csh or
tcsh, and C:\>
for the
Windows command.com or
cmd.exe command interpreters.
shell>mysql -u root test
shell>mysqladmin extended-status variables
shell>mysqlshow --help
shell>mysqldump --user=root personnel
Arguments that begin with a single or double dash
(‘-
’,
‘--
’) are option arguments. Options
typically specify the type of connection a program should make to
the server or affect its operational mode. Option syntax is
described in Section 4.3, “Specifying Program Options”.
Non-option arguments (arguments with no leading dash) provide
additional information to the program. For example, the
mysql program interprets the first non-option
argument as a database name, so the command mysql -u root
test
indicates that you want to use the
test
database.
Later sections that describe individual programs indicate which options a program understands and describe the meaning of any additional non-option arguments.
Some options are common to a number of programs. The most common
of these are the --host
(or -h
),
--user
(or -u
), and
--password
(or -p
) options that
specify connection parameters. They indicate the host where the
MySQL server is running, and the username and password of your
MySQL account. All MySQL client programs understand these options;
they allow you to specify which server to connect to and the
account to use on that server.
You may find it necessary to invoke MySQL programs using the
pathname to the bin
directory in which they
are installed. This is likely to be the case if you get a
“program not found” error whenever you attempt to run
a MySQL program from any directory other than the
bin
directory. To make it more convenient to
use MySQL, you can add the pathname of the
bin
directory to your PATH
environment variable setting. That enables you to run a program by
typing only its name, not its entire pathname. For example, if
mysql is installed in
/usr/local/mysql/bin
, you'll be able to run
it by invoking it as mysql; it will not be
necessary to invoke it as
/usr/local/mysql/bin/mysql.
Consult the documentation for your command interpreter for
instructions on setting your PATH
variable. The
syntax for setting environment variables is interpreter-specific.
(Some information is given in
Section 4.3.3, “Using Environment Variables to Specify Options”.)
There are several ways to specify options for MySQL programs:
List the options on the command line following the program name. This is most common for options that apply to a specific invocation of the program.
List the options in an option file that the program reads when it starts. This is common for options that you want the program to use each time it runs.
List the options in environment variables. This method is useful for options that you want to apply each time the program runs. In practice, option files are used more commonly for this purpose. However, Section 5.13.2, “Running Multiple Servers on Unix”, discusses one situation in which environment variables can be very helpful. It describes a handy technique that uses such variables to specify the TCP/IP port number and Unix socket file for both the server and client programs.
MySQL programs determine which options are given first by examining environment variables, then by reading option files, and then by checking the command line. If an option is specified multiple times, the last occurrence takes precedence. This means that environment variables have the lowest precedence and command-line options the highest.
You can take advantage of the way that MySQL programs process options by specifying default values for a program's options in an option file. That enables you to avoid typing them each time you run the program, but also allows you to override the defaults if necessary by using command-line options.
Program options specified on the command line follow these rules:
Options are given after the command name.
An option argument begins with one dash or two dashes,
depending on whether it has a short name or a long name.
Many options have both forms. For example,
-?
and --help
are the
short and long forms of the option that instructs a MySQL
program to display its help message.
Option names are case sensitive. -v
and
-V
are both legal and have different
meanings. (They are the corresponding short forms of the
--verbose
and --version
options.)
Some options take a value following the option name. For
example, -h localhost
or
--host=localhost
indicate the MySQL server
host to a client program. The option value tells the program
the name of the host where the MySQL server is running.
For a long option that takes a value, separate the option
name and the value by an ‘=
’
sign. For a short option that takes a value, the option
value can immediately follow the option letter, or there can
be a space between: -hlocalhost
and
-h localhost
are equivalent. An exception
to this rule is the option for specifying your MySQL
password. This option can be given in long form as
--password=
or as pass_val
--password
. In the latter case (with
no password value given), the program prompts you for the
password. The password option also may be given in short
form as
-p
or as
pass_val
-p
. However, for the short form, if the
password value is given, it must follow the option letter
with no intervening space. The reason
for this is that if a space follows the option letter, the
program has no way to tell whether a following argument is
supposed to be the password value or some other kind of
argument. Consequently, the following two commands have two
completely different meanings:
shell>mysql -ptest
shell>mysql -p test
The first command instructs mysql to use
a password value of test
, but specifies
no default database. The second instructs
mysql to prompt for the password value
and to use test
as the default database.
Some options control behavior that can be turned on or off. For
example, the mysql client supports a
--column-names
option that determines whether
or not to display a row of column names at the beginning of
query results. By default, this option is enabled. However, you
may want to disable it in some instances, such as when sending
the output of mysql into another program that
expects to see only data and not an initial header line.
To disable column names, you can specify the option using any of these forms:
--disable-column-names --skip-column-names --column-names=0
The --disable
and --skip
prefixes and the =0
suffix all have the same
effect: They turn the option off.
The “enabled” form of the option may be specified in any of these ways:
--column-names --enable-column-names --column-names=1
If an option is prefixed by --loose
, a program
does not exit with an error if it does not recognize the option,
but instead issues only a warning:
shell> mysql --loose-no-such-option
mysql: WARNING: unknown option '--no-such-option'
The --loose
prefix can be useful when you run
programs from multiple installations of MySQL on the same
machine and list options in an option file, An option that may
not be recognized by all versions of a program can be given
using the --loose
prefix (or
loose
in an option file). Versions of the
program that recognize the option process it normally, and
versions that do not recognize it issue a warning and ignore it.
Another option that may occasionally be useful with
mysql is the --execute
or
-e
option, which can be used to pass SQL
statements to the server. The statements must be enclosed by
single or double quotation marks. If you wish to use quoted
values within a statement, you should use double quotes for the
statement, and single quotes for any quoted values within the
statement. When this option is used, mysql
executes the statements and exits.
For example, you can use the following command to obtain a list of user accounts:
shell>mysql -u root -p --execute="SELECT User, Host FROM user" mysql
Enter password:******
+------+-----------+ | User | Host | +------+-----------+ | | gigan | | root | gigan | | | localhost | | jon | localhost | | root | localhost | +------+-----------+ shell>
Note that the long form (--execute
) is followed
by an equals sign (=
).
In the preceding example, the name of the
mysql
database was passed as a separate
argument. However, the same statement could have been executed
using this command, which specifies no default database:
mysql> mysql -u root -p --execute="SELECT User, Host FROM mysql.user"
Multiple SQL statements may be passed on the command line, separated by semicolons:
shell>mysql -u root -p -e "SELECT VERSION();SELECT NOW()"
Enter password:******
+------------+ | VERSION() | +------------+ | 5.0.19-log | +------------+ +---------------------+ | NOW() | +---------------------+ | 2006-01-05 21:19:04 | +---------------------+
The --execute
or -e
option may
also be used to pass commands in an analogous fashion to the
ndb_mgm management client for MySQL Cluster.
See Section 15.3.6, “Safe Shutdown and Restart”, for an example.
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.
To determine whether a program reads option files, invoke it
with the --help
option
(--verbose
and --help
for
mysqld). If the program reads option files,
the help message indicates which files it looks for and which
option groups it recognizes.
Note: Option files used with MySQL Cluster programs are covered in Section 15.4, “MySQL Cluster Configuration”.
On Windows, MySQL programs read startup options from the following files:
Filename | Purpose |
| Global options |
C:\my.cnf | Global options |
| Global Options |
defaults-extra-file | The file specified with
--defaults-extra-file= ,
if any |
WINDIR
represents the location of
your Windows directory. This is commonly
C:\WINDOWS
or
C:\WINNT
. You can determine its exact
location from the value of the WINDIR
environment variable using the following command:
C:\> echo %WINDIR%
INSTALLDIR
represents the
installation directory of MySQL. This is typically
C:\
where
PROGRAMDIR
\MySQL\MySQL
5.0 ServerPROGRAMDIR
represents the programs
directory (usually Program Files
on
English-language versions of Windows), when MySQL
5.0 has been installed using the installation and
configuration wizards. See
Section 2.3.4.14, “The Location of the my.ini File”.
On Unix, MySQL programs read startup options from the following files:
Filename | Purpose |
/etc/my.cnf | Global options |
$MYSQL_HOME/my.cnf | Server-specific options |
defaults-extra-file | The file specified with
--defaults-extra-file= ,
if any |
~/.my.cnf | User-specific options |
MYSQL_HOME
is an environment variable
containing the path to the directory in which the
server-specific my.cnf
file resides. (This
was DATADIR
prior to MySQL version
5.0.3.)
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:
Let BASEDIR
and
DATADIR
represent the pathnames
of the MySQL base directory and data directory,
respectively.
If there is a my.cnf
file in
DATADIR
but not in
BASEDIR
,
mysqld_safe sets
MYSQL_HOME
to
DATADIR
.
Otherwise, if MYSQL_HOME
is not set and
there is no my.cnf
file in
DATADIR
,
mysqld_safe sets
MYSQL_HOME
to
BASEDIR
.
Typically, DATADIR
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
the --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 of the --user
option is used as a
security precaution, to prevent a user specified in an option
file from being overridden on the command line.
Note: On Unix platforms, MySQL ignores configuration files that are world-writable. This is intentional, and acts 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 --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 should be
specified as quick
or
host=localhost
in an option file. To specify
an option of the form
--loose-
in
an option file, write it as
opt_name
loose-
.
opt_name
Empty lines in option files are ignored. Non-empty lines can take any of the following forms:
#
,
comment
;
comment
Comment lines start with ‘#
’
or ‘;
’. A
‘#
’ comment can start in the
middle of a line as well.
[
group
]
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.
opt_name
This is equivalent to
--
on
the command line.
opt_name
opt_name
=value
This is equivalent to
--
on the command line. In an option file, you can have spaces
around the ‘opt_name
=value
=
’ character,
something that is not true on the command line. You can
enclose the value within single quotes or double quotes,
which is useful if the value contains a
‘#
’ comment character or
whitespace.
For options that take a numeric value, the value can be given
with a suffix of K
, M
, or
G
(either uppercase or lowercase) to indicate
a multiplier of 1024, 10242 or
10243. For example, the following
command tells mysqladmin to ping the server
1024 times, sleeping 10 seconds between each ping:
mysql> mysqladmin --count=1K --sleep=10 ping
Leading and trailing blanks are automatically deleted from
option names and values. You may use the escape sequences
‘\b
’,
‘\t
’,
‘\n
’,
‘\r
’,
‘\\
’, and
‘\s
’ in option values to
represent the backspace, tab, newline, carriage return,
backslash, and space characters.
Because the ‘\\
’ escape sequence
represents a single backslash, you must write each
‘\
’ as
‘\\
’. Alternatively, you can
specify the value using ‘/
’
rather than ‘\
’ as the pathname
separator.
If an option group name is the same as a program name, options
in the group apply specifically to that program. For example,
the [mysqld]
and [mysql]
groups apply to the mysqld server and the
mysql client program, respectively.
The [client]
option group is read by all
client programs (but not by
mysqld). This allows 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
The preceding option file uses
syntax for the lines that set the
var_name
=value
key_buffer_size
and
max_allowed_packet
variables.
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-4.1]
,
[mysqld-5.0]
, and so forth. The
following group indicates that the --new
option
should be used only by MySQL servers with 5.0.x
version numbers:
[mysqld-5.0] new
Beginning with MySQL 5.0.4, 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, you
can use the following directive:
!include /home/me/myopt.cnf
To search the /home/mydir
directory and
read option files found there, you would use this directive:
!includedir /home/mydir
Note: Currently, any files to
be found and included using the !includedir
directive on Unix operating systems must
have filenames ending in .cnf
. On Windows,
this directive checks for files with the
.ini
or .cnf
extension.
Note that options read from included files are applied in the
context of the current option group. Suppose that you were to
write the following lines in my.cnf
:
[mysqld] !include /home/mydir/myopt.cnf
In this case, the myopt.cnf
file is
processed only for the server, and the
!include
directive is ignored by any client
applications. However, if you were to use the following lines,
the directory /home/mydir/my-dump-options
is checked for option files by mysqldump
only, and not by the server or by any other client applications:
[mysqldump] !includedir /home/mydir/my-dump-options
If you have a source distribution, you can find sample option
files named
my-
in
the xxxx
.cnfsupport-files
directory. If you have a
binary distribution, look in the
support-files
directory under your MySQL
installation directory. On Windows, the sample option files may
be located in the MySQL installation directory (see earlier in
this section or Chapter 2, Installing and Upgrading MySQL, if you do not know
where this is). 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.
Note: On Windows, the
.cnf
option file extension might not be
displayed.
All MySQL programs that support option files handle the
following options. They affect option-file handling, so they
must be given on the command line and not in an option file. To
work properly, each of these options must immediately follow the
command name, with the exception that
--print-defaults
may be used immediately after
--defaults-file
or
--defaults-extra-file
.
--no-defaults
Don't read any option files.
--print-defaults
Print the program name and all options that it gets from option files.
--defaults-file=
file_name
Use only the given option file.
file_name
is the full pathname to
the file.
--defaults-extra-file=
file_name
Read this option file after the global option file but (on
Unix) before the user option file.
file_name
is the full pathname to
the file.
In shell scripts, you can use the
my_print_defaults program to parse option
files and see what options would be used by a given program. 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 options in the appropriate group or groups before any command-line arguments. This works well 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 that 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. For details, see the documentation for your preferred interface.
To specify an option using an environment variable, set the
variable using the syntax appropriate for your command
processor. For example, on Windows or NetWare, you can set the
USER
variable to specify your MySQL account
name. To do so, use this syntax:
SET USER=your_name
The syntax on Unix depends on your shell. Suppose that you want
to specify the TCP/IP port number using the
MYSQL_TCP_PORT
variable. Typical syntax (such
as for sh, bash
,
zsh, and so on) is as follows:
MYSQL_TCP_PORT=3306 export MYSQL_TCP_PORT
The first command sets the variable, and the
export
command exports the variable to the
shell environment so that its value becomes accessible to MySQL
and other processes.
For csh and tcsh, use setenv to make the shell variable available to the environment:
setenv MYSQL_TCP_PORT 3306
The commands to set environment variables can be executed at
your command prompt to take effect immediately, but the settings
persist only until you log out. To have the settings take effect
each time you log in, place the appropriate command or commands
in a startup file that your command interpreter reads each time
it starts. Typical startup files are
AUTOEXEC.BAT
for Windows,
.bash_profile
for bash,
or .tcshrc
for tcsh.
Consult the documentation for your command interpreter for
specific details.
Appendix F, Environment Variables, lists all environment variables that affect MySQL program operation.
Many MySQL programs have internal variables that can be set at
runtime. Program variables are set the same way as any other
long option that takes a value. For example,
mysql has a
max_allowed_packet
variable that controls the
maximum size of its communication buffer. To set the
max_allowed_packet
variable for
mysql to a value of 16MB, use either of the
following commands:
shell>mysql --max_allowed_packet=16777216
shell>mysql --max_allowed_packet=16M
The first command specifies the value in bytes. The second
specifies the value in megabytes. For variables that take a
numeric value, the value can be given with a suffix of
K
, M
, or
G
(either uppercase or lowercase) to indicate
a multiplier of 1024, 10242 or
10243. (For example, when used to set
max_allowed_packet
, the suffixes indicate
units of kilobytes, megabytes, or gigabygtes.)
In an option file, variable settings are given without the leading dashes:
[mysql] max_allowed_packet=16777216
Or:
[mysql] max_allowed_packet=16M
If you like, underscores in a variable name can be specified as dashes. The following option groups are equivalent. Both set the size of the server's key buffer to 512MB:
[mysqld] key_buffer_size=512M [mysqld] key-buffer-size=512M
Note: Before MySQL 4.0.2, the
only syntax for setting program variables was
--set-variable=
(or
option
=value
set-variable=
in option files). This syntax still is recognized, but is
deprecated as of MySQL 4.0.2.
option
=value
Many server system variables can also be set at runtime. For details, see Section 5.2.3.2, “Dynamic System Variables”.