4.1.3.3 Using Client Programs in a Multiple-Server Environment

When you want to connect with a client program to a MySQL server that is listening to different network interfaces than those compiled into your client, you can use one of the following methods:

• Start the client with --host=host_name --port=port_number to connect via TCP/IP to a remote host, or with --host=localhost --socket=file_name to connect to a local host via a Unix socket or a Windows named pipe.
• As of MySQL 4.1, start the client with --protocol=tcp to connect via TCP/IP, --protocol=socket to connect via a Unix socket, --protocol=pipe to connect via a named pipe, or --protocol=memory to connect via shared memory. For TCP/IP connections, you may also need to specify --host and --port options. For the other types of connections, you may need to specify a --socket option to specify a socket or named pipe name, or a --shared-memory-base-name option to specify the shared memory name.
• On Unix, set the MYSQL_UNIX_PORT and MYSQL_TCP_PORT environment variables to point to the Unix socket and TCP/IP port before you start your clients. If you normally use a specific socket or port, you can place commands to set these environment variables in your `.login' file so that they apply each time you log in. See section F Environment Variables.
• Specify the default socket and TCP/IP port in the [client] group of an option file. Foe example, you can use `C:\my.cnf' on Windows, or the `.my.cnf' file in your home directory on Unix. See section 4.1.2 `my.cnf' Option Files.
• In a C program, you can specify the port or socket arguments in the mysql_real_connect() call. You can also have the program read option files by calling mysql_options(). See section 9.1.3 C API Function Descriptions.
• If you are using the Perl DBD::mysql module, you can read the options from the MySQL option files. For example:

  $dsn = "DBI:mysql:test;mysql_read_default_group=client;"
          . "mysql_read_default_file=/usr/local/mysql/data/my.cnf";
  $dbh = DBI->connect($dsn, $user, $password);
  

  See section 9.5.2 The DBI Interface.

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