For a client program to be able to connect to the MySQL server, it must use the proper connection parameters, such as the name of the host where the server is running and the user name and password of your MySQL account. Each connection parameter has a default value, but you can override them as necessary using program options specified either on the command line or in an option file.
The examples here use the mysql client program, but the principles apply to other clients such as mysqldump, mysqladmin, or mysqlshow.
This command invokes mysql without specifying any connection parameters explicitly:
shell> mysql
Because there are no parameter options, the default values apply:
The default host name is localhost
. On
Unix, this has a special meaning, as described later.
The default user name is ODBC
on Windows or
your Unix login name on Unix.
No password is sent if neither -p
nor
--password
is given.
For mysql, the first nonoption argument is taken as the name of the default database. If there is no such option, mysql does not select a default database.
To specify the host name and user name explicitly, as well as a password, supply appropriate options on the command line:
shell>mysql --host=localhost --user=myname --password=mypass mydb
shell>mysql -h localhost -u myname -pmypass mydb
For password options, the password value is optional:
If you use a -p
or
--password
option and specify
the password value, there must be no
space between -p
or
--password=
and the password
following it.
If you use a -p
or
--password
option but do not
specify the password value, the client program prompts you to
enter the password. The password is not displayed as you enter
it. This is more secure than giving the password on the
command line. Other users on your system may be able to see a
password specified on the command line by executing a command
such as ps auxw. See
Section 5.5.6.2, “End-User Guidelines for Password Security”.
As just mentioned, including the password value on the command
line can be a security risk. To avoid this problem, specify the
--password
or -p
option without
any following password value:
shell>mysql --host=localhost --user=myname --password mydb
shell>mysql -h localhost -u myname -p mydb
When the password option has no password value, the client program
prints a prompt and waits for you to enter the password. (In these
examples, mydb
is not
interpreted as a password because it is separated from the
preceding password option by a space.)
On some systems, the library routine that MySQL uses to prompt for a password automatically limits the password to eight characters. That is a problem with the system library, not with MySQL. Internally, MySQL does not have any limit for the length of the password. To work around the problem, change your MySQL password to a value that is eight or fewer characters long, or put your password in an option file.
On Unix, MySQL programs treat the host name
localhost
specially, in a way that is likely
different from what you expect compared to other network-based
programs. For connections to localhost
, MySQL
programs attempt to connect to the local server by using a Unix
socket file. This occurs even if a
--port
or -P
option is given to specify a port number. To ensure that the
client makes a TCP/IP connection to the local server, use
--host
or -h
to
specify a host name value of 127.0.0.1
, or the
IP address or name of the local server. You can also specify the
connection protocol explicitly, even for
localhost
, by using the
--protocol=TCP
option. For
example:
shell>mysql --host=127.0.0.1
shell>mysql --protocol=TCP
The --protocol
option enables you
to establish a particular type of connection even when the other
options would normally default to some other protocol.
On Windows, you can force a MySQL client to use a named-pipe
connection by specifying the
--pipe
or
--protocol=PIPE
option, or by
specifying .
(period) as the host name. If
named-pipe connections are not enabled, an error occurs. Use the
--socket
option to specify the
name of the pipe if you do not want to use the default pipe name.
Connections to remote servers always use TCP/IP. This command
connects to the server running on
remote.example.com
using the default port
number (3306):
shell> mysql --host=remote.example.com
To specify a port number explicitly, use the
--port
or -P
option:
shell> mysql --host=remote.example.com --port=13306
You can specify a port number for connections to a local server,
too. However, as indicated previously, connections to
localhost
on Unix will use a socket file by
default. You will need to force a TCP/IP connection as already
described or any option that specifies a port number will be
ignored.
For this command, the program uses a socket file on Unix and the
--port
option is ignored:
shell> mysql --port=13306 --host=localhost
To cause the port number to be used, invoke the program in either of these ways:
shell>mysql --port=13306 --host=127.0.0.1
shell>mysql --port=13306 --protocol=TCP
The following list summarizes the options that can be used to control how client programs connect to the server:
--host=
,
host_name
-h
host_name
The host where the server is running. The default value is
localhost
.
--password[=
,
pass_val
]-p[
pass_val
]
The password of the MySQL account. As described earlier, the
password value is optional, but if given, there must be
no space between -p
or
--password=
and the password
following it. The default is to send no password.
--pipe
, -W
On Windows, connect to the server via a named pipe. This
option applies for connections to a local server only. The
server must have been started with the
--enable-named-pipe
option to
enable named-pipe connections.
--port=
,
port_num
-P
port_num
The port number to use for the connection, for connections made via TCP/IP. The default port number is 3306.
--protocol={TCP|SOCKET|PIPE|MEMORY}
This option explicitly specifies a protocol to use for
connecting to the server. It is useful when the other
connection parameters normally would cause a protocol to be
used other than the one you want. For example, connections on
Unix to localhost
are made via a Unix
socket file by default:
shell> mysql --host=localhost
To force a TCP/IP connection to be used instead, specify a
--protocol
option:
shell> mysql --host=localhost --protocol=TCP
The following table shows the allowable
--protocol
option values and
indicates the platforms on which each value may be used. The
values are not case sensitive.
--protocol
Value |
Connection Protocol | Allowable Operating Systems |
TCP |
TCP/IP connection to local or remote server | All |
SOCKET |
Unix socket file connection to local server | Unix only |
PIPE |
Named-pipe connection to local server | Windows only |
MEMORY |
Shared-memory connection to local server | Windows only |
--shared-memory-base-name=
name
On Windows, the shared-memory name to use, for connections
made via shared memory to a local server. The default value is
MYSQL
. The shared-memory name is case
sensitive.
The server must be started with the
--shared-memory
option to
enable shared-memory connections.
--socket=
,
file_name
-S
file_name
On Unix, the name of the Unix socket file to use, for
connections made via a named pipe to a local server. The
default Unix socket file name is
/tmp/mysql.sock
.
On Windows, the name of the named pipe to use, for connections
to a local server. The default Windows pipe name is
MySQL
. The pipe name is not case sensitive.
The server must be started with the
--enable-named-pipe
option to
enable named-pipe connections.
Options that begin with --ssl
are used for establishing a secure connection to the server
via SSL, if the server is configured with SSL support. For
details, see Section 5.5.7.3, “SSL Command Options”.
--user=
,
user_name
-u
user_name
The user name of the MySQL account you want to use. The
default user name is ODBC
on Windows or
your Unix login name on Unix.
It is possible to specify different default values to be used when you make a connection so that you need not enter them on the command line each time you invoke a client program. This can be done in a couple of ways:
You can specify connection parameters in the
[client]
section of an option file. The
relevant section of the file might look like this:
[client] host=host_name
user=user_name
password=your_pass
Section 4.2.3.3, “Using Option Files”, discusses option files further.
You can specify some connection parameters using environment
variables. The host can be specified for
mysql using MYSQL_HOST
.
The MySQL user name can be specified using
USER
(this is for Windows and NetWare
only). The password can be specified using
MYSQL_PWD
, although this is insecure; see
Section 5.5.6.2, “End-User Guidelines for Password Security”. For a list of
variables, see Section 2.14, “Environment Variables”.
User Comments
Add your own comment.