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       mysqld_multi - manage multiple MySQL servers


       mysqld_multi [options] {start|stop|report} [GNR[,GNR] ...]


       mysqld_multi is designed to manage several mysqld processes that listen for connections on
       different Unix socket files and TCP/IP ports. It can start or stop servers, or report
       their current status.

       mysqld_multi searches for groups named [mysqldN] in my.cnf (or in the file named by the
       --config-file option).  N can be any positive integer. This number is referred to in the
       following discussion as the option group number, or GNR. Group numbers distinguish option
       groups from one another and are used as arguments to mysqld_multi to specify which servers
       you want to start, stop, or obtain a status report for. Options listed in these groups are
       the same that you would use in the [mysqld] group used for starting mysqld. (See, for
       example, Section, “Starting and Stopping MySQL Automatically”.) However, when
       using multiple servers, it is necessary that each one use its own value for options such
       as the Unix socket file and TCP/IP port number. For more information on which options must
       be unique per server in a multiple-server environment, see Section 5.6, “Running Multiple
       MySQL Instances on One Machine”.

       To invoke mysqld_multi, use the following syntax:

           shell> mysqld_multi [options] {start|stop|report} [GNR[,GNR] ...]

       start, stop, and report indicate which operation to perform. You can perform the
       designated operation for a single server or multiple servers, depending on the GNR list
       that follows the option name. If there is no list, mysqld_multi performs the operation for
       all servers in the option file.

       Each GNR value represents an option group number or range of group numbers. The value
       should be the number at the end of the group name in the option file. For example, the GNR
       for a group named [mysqld17] is 17. To specify a range of numbers, separate the first and
       last numbers by a dash. The GNR value 10-13 represents groups [mysqld10] through
       [mysqld13]. Multiple groups or group ranges can be specified on the command line,
       separated by commas. There must be no whitespace characters (spaces or tabs) in the GNR
       list; anything after a whitespace character is ignored.

       This command starts a single server using option group [mysqld17]:

           shell> mysqld_multi start 17

       This command stops several servers, using option groups [mysqld8] and [mysqld10] through

           shell> mysqld_multi stop 8,10-13

       For an example of how you might set up an option file, use this command:

           shell> mysqld_multi --example

       mysqld_multi searches for option files as follows:

       ·   With --no-defaults, no option files are read.

       ·   With --defaults-file=file_name, only the named file is read.

       ·   Otherwise, option files in the standard list of locations are read, including any file
           named by the --defaults-extra-file=file_name option, if one is given. (If the option
           is given multiple times, the last value is used.)

       Option files read are searched for [mysqld_multi] and [mysqldN] option groups. The
       [mysqld_multi] group can be used for options to mysqld_multi itself.  [mysqldN] groups can
       be used for options passed to specific mysqld instances.

       The [mysqld] or [mysqld_safe] groups can be used for common options read by all instances
       of mysqld or mysqld_safe. You can specify a --defaults-file=file_name option to use a
       different configuration file for that instance, in which case the [mysqld] or
       [mysqld_safe] groups from that file will be used for that instance.

       mysqld_multi supports the following options.

       ·   --help

           Display a help message and exit.

       ·   --config-file=file_name

           This option is deprecated. If given, it is treated the same way as
           --defaults-extra-file, described earlier.  --config-file was removed in MySQL 5.5.3.

       ·   --example

           Display a sample option file.

       ·   --log=file_name

           Specify the name of the log file. If the file exists, log output is appended to it.

       ·   --mysqladmin=prog_name

           The mysqladmin binary to be used to stop servers.

       ·   --mysqld=prog_name

           The mysqld binary to be used. Note that you can specify mysqld_safe as the value for
           this option also. If you use mysqld_safe to start the server, you can include the
           mysqld or ledir options in the corresponding [mysqldN] option group. These options
           indicate the name of the server that mysqld_safe should start and the path name of the
           directory where the server is located. (See the descriptions for these options in
           mysqld_safe(1).) Example:

               mysqld = mysqld-debug
               ledir  = /opt/local/mysql/libexec

       ·   --no-log

           Print log information to stdout rather than to the log file. By default, output goes
           to the log file.

       ·   --password=password

           The password of the MySQL account to use when invoking mysqladmin. Note that the
           password value is not optional for this option, unlike for other MySQL programs.

       ·   --silent

           Silent mode; disable warnings.

       ·   --tcp-ip

           Connect to each MySQL server through the TCP/IP port instead of the Unix socket file.
           (If a socket file is missing, the server might still be running, but accessible only
           through the TCP/IP port.) By default, connections are made using the Unix socket file.
           This option affects stop and report operations.

       ·   --user=user_name

           The user name of the MySQL account to use when invoking mysqladmin.

       ·   --verbose

           Be more verbose.

       ·   --version

           Display version information and exit.

       Some notes about mysqld_multi:

       ·   Most important: Before using mysqld_multi be sure that you understand the meanings of
           the options that are passed to the mysqld servers and why you would want to have
           separate mysqld processes. Beware of the dangers of using multiple mysqld servers with
           the same data directory. Use separate data directories, unless you know what you are
           doing. Starting multiple servers with the same data directory does not give you extra
           performance in a threaded system. See Section 5.6, “Running Multiple MySQL Instances
           on One Machine”.


               Make sure that the data directory for each server is fully accessible to the Unix
               account that the specific mysqld process is started as.  Do not use the Unix root
               account for this, unless you know what you are doing. See Section 5.3.6, “How to
               Run MySQL as a Normal User”.

       ·   Make sure that the MySQL account used for stopping the mysqld servers (with the
           mysqladmin program) has the same user name and password for each server. Also, make
           sure that the account has the SHUTDOWN privilege. If the servers that you want to
           manage have different user names or passwords for the administrative accounts, you
           might want to create an account on each server that has the same user name and
           password. For example, you might set up a common multi_admin account by executing the
           following commands for each server:

               shell> mysql -u root -S /tmp/mysql.sock -p
               Enter password:
               mysql> GRANT SHUTDOWN ON *.*
                   -> TO ´multi_admin´@´localhost´ IDENTIFIED BY ´multipass´;

           See Section 5.4, “The MySQL Access Privilege System”. You have to do this for each
           mysqld server. Change the connection parameters appropriately when connecting to each
           one. Note that the host name part of the account name must permit you to connect as
           multi_admin from the host where you want to run mysqld_multi.

       ·   The Unix socket file and the TCP/IP port number must be different for every mysqld.
           (Alternatively, if the host has multiple network addresses, you can use --bind-address
           to cause different servers to listen to different interfaces.)

       ·   The --pid-file option is very important if you are using mysqld_safe to start mysqld
           (for example, --mysqld=mysqld_safe) Every mysqld should have its own process ID file.
           The advantage of using mysqld_safe instead of mysqld is that mysqld_safe monitors its
           mysqld process and restarts it if the process terminates due to a signal sent using
           kill -9 or for other reasons, such as a segmentation fault. Please note that the
           mysqld_safe script might require that you start it from a certain place. This means
           that you might have to change location to a certain directory before running
           mysqld_multi. If you have problems starting, please see the mysqld_safe script. Check
           especially the lines:

               # Check if we are starting this relative (for the binary release)
               if test -d $MY_PWD/data/mysql -a \
                  -f ./share/mysql/english/errmsg.sys -a \
                  -x ./bin/mysqld

           The test performed by these lines should be successful, or you might encounter
           problems. See mysqld_safe(1).

       ·   You might want to use the --user option for mysqld, but to do this you need to run the
           mysqld_multi script as the Unix superuser (root). Having the option in the option file
           doesn´t matter; you just get a warning if you are not the superuser and the mysqld
           processes are started under your own Unix account.

       The following example shows how you might set up an option file for use with mysqld_multi.
       The order in which the mysqld programs are started or stopped depends on the order in
       which they appear in the option file. Group numbers need not form an unbroken sequence.
       The first and fifth [mysqldN] groups were intentionally omitted from the example to
       illustrate that you can have “gaps” in the option file. This gives you more flexibility.

           # This file should probably be in your home dir (~/.my.cnf)
           # or /etc/my.cnf
           # Version 2.1 by Jani Tolonen
           mysqld     = /usr/local/bin/mysqld_safe
           mysqladmin = /usr/local/bin/mysqladmin
           user       = multi_admin
           password   = multipass
           socket     = /tmp/mysql.sock2
           port       = 3307
           pid-file   = /usr/local/mysql/var2/hostname.pid2
           datadir    = /usr/local/mysql/var2
           language   = /usr/local/share/mysql/english
           user       = john
           socket     = /tmp/mysql.sock3
           port       = 3308
           pid-file   = /usr/local/mysql/var3/hostname.pid3
           datadir    = /usr/local/mysql/var3
           language   = /usr/local/share/mysql/swedish
           user       = monty
           socket     = /tmp/mysql.sock4
           port       = 3309
           pid-file   = /usr/local/mysql/var4/hostname.pid4
           datadir    = /usr/local/mysql/var4
           language   = /usr/local/share/mysql/estonia
           user       = tonu
           socket     = /tmp/mysql.sock6
           port       = 3311
           pid-file   = /usr/local/mysql/var6/hostname.pid6
           datadir    = /usr/local/mysql/var6
           language   = /usr/local/share/mysql/japanese
           user       = jani

       See Section, “Using Option Files”.


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