MySQL database on Linux Tutorial

The MySQL Database Installation and configuration:

Red Hat / Fedora Core RPM Packages:

mysql-VERSION.i386.rpm (Required)
mysql-server-VERSION.i386.rpm (Required)
mysqlclient9-VERSION.i386.rpm (Shared object libraries)
mysql-devel-VERSION.i386.rpm (C include files and libraries for software developers)
php-mysql-VERSION.i386.rpm (For accessing MySQL database from php)

Install: rpm -ivh mysql-VERSION.i386.rpm mysql-server-VERSION.i386.rpm mysqlclient9-VERSION.i386.rpm
Check if installed: rpm -q mysql mysql-server mysqlclient9
The examples on this page used mySQL 3.23.58 which is used in Red Hat 7, 8, 9 and Fedora Core 1, 2, 3.
Also see YoLinux.com systems administration - using RPM to set GPG signatures and install RPM packages.

Installing MySQL.com RPM packages: If instaling newer versions of MySQL from RPM packages obtained from MySQL.com, you must first import and register their public GPG key:

Download public key named build@mysql.com from http://www.keyserver.net/ with one of two methods:
- wget --output-document=pubkey_mysql.asc http://keyserver.veridis.com:11371/export?id=-8326718950139043339
  (Saves key 0x5072E1F5 as file pubkey_mysql.asc)
- gpg --keyserver keyserver.veridis.com --recv-key 5072e1f5
  gpg --export -a 5072e1f5 > pubkey_mysql.asc
Import key: rpm --import pubkey_mysql.asc

[Potential Pitfall]: Your system should have a host name other than the default "localhost". Give your systems a host name if you get the following installation error:

ERROR: 1062  Duplicate entry 'localhost-root' for key 1
ERROR: 1062  Duplicate entry 'localhost-' for key 1

Use the command hostname to give your system a hostname and also set in the configuration file /etc/sysconfig/network

Ubuntu / Debian package installation:

apt-get install mysql-client
apt-get install mysql-server

Start the database:

Start the database: /etc/rc.d/init.d/mysqld start
(The script will run mysql_install_db to create a default database in /var/lib/mysql/mysql/ if the mysql init script has never been run before. The install script will not be run again as long as the default database directory exists.)
The database executes as user mysqld and group mysqld.

Notes:

One may manually initialize the database with the command: /usr/bin/mysql_install_db
Creates system tables in /var/lib/mysql/mysql/
Only execute the first time MySQL is installed.
Databases located in: /var/lib/mysql/

Default config file installed by RPM: /etc/my.cnf
(Ubuntu: /etc/mysql/my.cnf)

[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock

[mysql.server]
user=mysql
basedir=/var/lib

[safe_mysqld]
err-log=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid

Post installation:

Admin user id: root
Default password: blank

The first task is to assign a password:

[prompt]$ mysqladmin -u root password 'new-password'

Note: the following SQL commands will also work:

mysql> USE mysql;
mysql> UPDATE user SET Password=PASSWORD('new-password') WHERE user='root';
mysql> FLUSH PRIVILEGES;

Create a database: (Creates directory /var/lib/mysql/bedrock)
[prompt]$ mysqladmin -h localhost -u root -ppassword create bedrock
(or use SQL command: CREATE DATABASE bedrock;)
Show all mysql databases: mysqlshow -u root -ppassword

Add tables, data, etc:
Connect to database and issue the following SQL commands:

[prompt]$ mysql -h localhost -u root -ppassword                ...                mysql> show databases;             - List all databases in MySQL.                +----------+                | Database |                +----------+                | bedrock  |                | mysql    |                | test     |                +----------+                mysql> use bedrock;                - Define database to connect to. Refers to directory path: /var/lib/mysql/bedrock                mysql> create table employee (Name char(20),Dept char(20),jobTitle char(20));
mysql> DESCRIBE employee;       - View the table just created. Same as "show columns from employee;"                +----------+----------+------+-----+---------+-------+                | Field    | Type     | Null | Key | Default | Extra |                +----------+----------+------+-----+---------+-------+                | Name     | char(20) | YES  |     | NULL    |       |                | Dept     | char(20) | YES  |     | NULL    |       |                | jobTitle | char(20) | YES  |     | NULL    |       |                +----------+----------+------+-----+---------+-------+                3 rows in set (0.03 sec)                mysql> show tables;
+-------------------+
| Tables_in_bedrock |
+-------------------+
| employee          |
+-------------------+

mysql> INSERT INTO employee VALUES ('Fred Flinstone','Quarry Worker','Rock Digger');
mysql> INSERT INTO employee VALUES ('Wilma Flinstone','Finance','Analyst');
mysql> INSERT into employee values ('Barney Rubble','Sales','Neighbor');
mysql> INSERT INTO employee VALUES ('Betty Rubble','IT','Neighbor');

Note: Data type used was CHAR. Other data types include:

CHAR(M) : Fixed length string. Always stores M characters whether it is holding 2 or 20 characters. Where M can range 1 to 255 characters.
VARCHAR(M) : Variable length. Stores only the string. If M is defined to be 200 but the string is 20 characters long, only 20 characters are stored. Slower than CHAR.
INT : Ranging from -2147483648 to 2147483647 or unsigned 0 to 4294967295
FLOAT(M,N) : FLOAT(4,2) - Four digits total of which 2 are after the decimal. i.e. 12.34 Values are rounded to fit format if they are too large.
DATE, TEXT, BLOB, SET, ENUM

Add a user. Use the MySQL SQL console to enter SQL commands. The command mysql with the correct login/password will connect you to the database. The admin tables are stored in the database "mysql".

[prompt]$ mysql -h localhost -u root -ppassword                Welcome to the MySQL monitor.  Commands end with ; or \g.                Your MySQL connection id is 1 to server version: 3.23.41                Type 'help;' or '\h' for help. Type '\c' to clear the buffer.                mysql> USE mysql;
mysql> SHOW TABLES;
+-----------------+
| Tables_in_mysql |
+-----------------+
| columns_priv    |
| db              |
| func            |
| host            |
| tables_priv     |
| user            |
+-----------------+
mysql> INSERT INTO user (Host, User, Password, Select_priv) VALUES ('', 'Dude1', password('supersecret'), 'Y');
mysql> FLUSH PRIVILEGES;   - Required each time one makes a change to the GRANT table                mysql> GRANT ALL PRIVILEGES ON bedrock.* TO Dude1;
mysql> FLUSH PRIVILEGES;   - Required each time one makes a change to the GRANT table                mysql> quit

Note:

There is NO space between the -p and the password! You can omit the password and you will be prompted for it.
The SQL flush command is equivalent to issuing the command:
[prompt]$ mysqladmin reload

Test the database:

mysql> SELECT * from employee;
+-----------------+---------------+-------------+
| Name            | Dept          | jobTitle    |
+-----------------+---------------+-------------+
| Fred Flinstone  | Quarry Worker | Rock Digger |
| Wilma Flinstone | Finance       | Analyst     |
| Barney Rubble   | Sales         | Neighbor    |
| Betty Rubble    | IT            | Neighbor    |
+-----------------+---------------+-------------+
1 row in set (0.00 sec)

mysql> SELECT name FROM employee WHERE dept='Sales';
+---------------+
| name          |
+---------------+
| Barney Rubble |
+---------------+
1 row in set (0.00 sec)

Quit from the SQL shell:
[prompt]$ quit

Shutting down the database:

[prompt]$ mysqladmin -u root -ppassword shutdown       - PREFERRED                OR                [prompt]$ /etc/rc.d/init.d/mysqld stop
OR                [prompt]$ service mysqld stop

Documentation in /usr/share/doc/mysql-3.23.41/ (local file)

Security:

Security and database access is controlled by the GRANT tables. Access to connect to the database and access to process the transaction (table and column access, etc.) are both required. Privileges are searched in the following order:

user table
db and host table
tables_priv
columns_priv

Use the user table to grant connection privileges to database by a user (host, user name and password). Grant database and table access for transaction access. i.e. grant "SELECT", "UPDATE", "CREATE", "DELETE", "ALTER" etc. permission for database, table, field (columns) or database server access.

Access can be granted by network permissions: GRANT ALL PRIVILEGES on bedrock.* to david@'192.168.10.0/255.255.255.0';
This grants access from nodes 192.168.10.0 - 192.168.10.255. Or the network definitions can reference resolvable names: '%.domain.com'. The host definition of '%' or '' (null) refers to any host. (..according to the documentation. My experience is that in the mysql.user table use only '%' for "Host" to refer to any host.)

     mysql> GRANT ALL PRIVILEGES on bedrock.* to david@'%';
     mysql> FLUSH PRIVILEGES;

or (more promiscuous)

     mysql> GRANT ALL PRIVILEGES on *.* to david@'%' identified by 'david';
     mysql> FLUSH PRIVILEGES;

Show privileges: SHOW GRANTS FOR Dude2@'%';

Network security: Use firewall rules (ipchains or iptables) to block internet access to port 3306. (default port used by MySQL)

Note: I have found that when adding access from "anywhere" ('%'), the MySQL database table 'user' requires two entries, 'localhost' and '%'. Also, it is typically safer to allow more privileges to those with 'localhost' access than to users from '%' ("anywhere").

Passwords and connecting to the databse:

Connect: [prompt]$ mysql -h host_name -u user_name -ppassword
Using default blank password: [prompt]$ mysql -h localhost -u root -p
If a password is required, you will be prompted. Note, blank passwords are a security hole which has already lead to one mySQL internet worm. Change any default blank passwords.
Delete null/blank users: DELETE FROM user WHERE User = '';
Beware of open access permissions from hosts '%': SELECT * FROM db WHERE Host = '%';

Change a password:

    [prompt]$ mysqladmin -u root -p password new-password

You will be prompted to enter the old root password to complete this command.
or:

    [prompt]$ mysqladmin -u root -pold-password password new-password

or:

    mysql> SET PASSWORD FOR root@'localhost' = PASSWORD('supersecret');
    mysql> FLUSH PRIVILEGES;

As an added security precaution it is wise to delete any user id not used. i.e. any defaults generated for demonstration purposes.
Note that the default port used by MySQL is 3306. This can be protected with firewall rules. See the YoLinux IpTables tutorial.

Debian/Ubuntu upgrades: Note that the Debian/Ubuntu distribution will have an additional file /etc/mysql/debian.conf. This file holds a password for the user "debian-sys-maint" which is used by the install tool dpkg to perform database upgrades. This can also be used in emergencies if you forget the root password. It is also a security hole if the file is available to others.

[Potential Pitfall]: It is very easy to make mistakes which get entered into important tables. If you enter the command twice you may have one incorrect and one correct entry. Look at the table data after a mistake to see what happened in case it needs to be fixed.
Example:

mysql> USE mysql;
mysql> SELECT User,Password,Host from user;
+-------+------------------+------------+
| User  | Password         | Host       |
+-------+------------------+------------+
| root  | 99a1544eb571ad63 | localhost  |
|       |                  | localhost  |
| Dude1 | 81a10dba5f6f2144 |            |
| Dude1 |                  |            |
| Dude2 | 92b10dba6f7f3155 | %          |
+-------+------------------+------------+
5 rows in set (0.00 sec)
mysql> DELETE FROM user WHERE User='' AND Host='localhost';
mysql> DELETE FROM user WHERE User='Dude1' AND Password='';
mysql> FLUSH PRIVILEGES;
mysql> QUIT

User entries may also be found in the table mysql.db.

mysql> DELETE FROM db WHERE User='Dude3' AND Host='localhost';

[Potential Pitfall]: Any changes (UPDATE) to the user table will require a "FLUSH PRIVILEGES" before the changes will be effective.

mysql> UPDATE user SET Host='%' WHERE User='Dude2';
mysql> FLUSH PRIVILEGES;

This will allow a connection with mysql client from any host:
[prompt]$ mysql -u Dude2 -ppassword -h node.your-domain.com

MySQL root password recovery:

As Linux system root user stop the database process: /etc/init.d/mysql stop
(or: service mysql stop)
Start MySQL in safe mode and skip the use of the "grant tables": /usr/bin/mysqld_safe --user=mysql --socket=/var/lib/mysql/mysql.sock --pid-file=/var/run/mysqld/mysqld.pid --datadir=/var/lib/mysql --skip-grant-tables --skip-networking &
Reset the MySQL root password: mysqladmin -u root flush-privileges password newpassword
Stop MySQL running in safe mode: kill `cat /var/run/mysqld/mysqld.pid`
Start MySQL: /etc/init.d/mysql start
The new MySQL root password can now be used: mysql -u root -p
Respond withthe password: newpassword

Disabling networking:

If your configuration is a web server interacting with a mySQL database running on the same "localhost" then one may turn off network access to tighten security. Edit shell script:

/usr/bin/safe_mysqld (Fedora Core 3)
/usr/bin/mysqld_safe (Red Hat Enterprise Linux 4)

..
...
  if test -z "$args"
  then
    $NOHUP_NICENESS $ledir/$MYSQLD $defaults --basedir=$MY_BASEDIR_VERSION \
                      --datadir=$DATADIR $USER_OPTION --pid-file=$pid_file \
                      --skip-networking --skip-locking >> $err_log 2>&1
  else
    eval "$NOHUP_NICENESS $ledir/$MYSQLD $defaults --basedir=$MY_BASEDIR_VERSION \
                      --datadir=$DATADIR $USER_OPTION --pid-file=$pid_file \
                      --skip-networking --skip-locking $args >> $err_log 2>&1"
  fi
...
..

Add the flag "--skip-networking" marked in bold.

Mysql 5.0: Networking is disabled by default on the default Ubuntu installation. To enable remote database access, comment out (or remove) the following line with a "#" in the file: /etc/mysql/my.cnf

...            ...            bind-address           = 127.0.0.1            ...            ...

Restart the database after making changes.

MySQL Admin Commands:

Statistics: [prompt]$ mysqladmin version
List database environment: [prompt]$ mysqladmin variables
Show if database is running: [prompt]$ mysqladmin ping

Show databases available:

[prompt]$ mysqlshow

+-----------+
| Databases |
+-----------+
| bedrock   |
| mysql     |
| test      |
+-----------+

mysql> SHOW DATABASES;

Delete database: mysql> drop database bedrock;

Show list of active threads in server:

[prompt]$ mysqladmin -h localhost -u root -p processlist

+----+------+-----------+----+---------+------+-------+------------------+
| Id | User | Host      | db | Command | Time | State | Info             |
+----+------+-----------+----+---------+------+-------+------------------+
| 15 | root | localhost |    | Query   | 0    |       | show processlist |
+----+------+-----------+----+---------+------+-------+------------------+

Delete a database: [prompt]$ mysqladmin drop database-name
Execute SQL from Linux command line interface:
[prompt]$ mysql -h localhost -u root -p -e "select host,db,user from db" mysql

Execute SQL command file from Linux command line interface:

[prompt]$ mysql -h localhost -u root -p database-name < text-file-with-sql-statements.sql

Loadtest (benchmark) the system:

[prompt]$ cd sql-bench
[prompt]$ run-all-tests
or                [prompt]$ mysql -vvf test < ./tests/auto_increment.tst

Sample SQL:

SQL requests are either administrative or data-related. The following are sample SQL segments and are not necessarily pertinent to the previous example:

mysql> CREATE DATABASE bedrock;
mysql> USE bedrock;
mysql> SHOW tables;
mysql> SHOW DATABASES;
mysql> LOAD DATA LOCAL INFILE "data.txt" INTO TABLE bedrock;
mysql> SELECT DISTINCT dept FROM  bedrock;
mysql> CREATE TABLE pet (name VARCHAR(20), owner VARCHAR(20), species VARCHAR(20), sex CHAR(1), birth DATE, death DATE);
mysql> SELECT * FROM pet WHERE species = "snake" OR species = "bird";
mysql> SELECT * FROM pet WHERE species = "dog" AND sex = "f";
mysql> SELECT * FROM pet WHERE birth >= "1998-1-1";
mysql> SELECT name, birth FROM pet ORDER BY birth DESC;
mysql> SELECT * FROM pet WHERE name LIKE "b%";
mysql> SELECT * FROM pet WHERE name REGEXP "^b";
mysql> SELECT species, COUNT(*) FROM pet GROUP BY species;
mysql> SELECT MAX(article) AS article FROM shop;
mysql> DROP TABLE tmp;
mysql> CREATE TABLE retired_employee (
                    Name char(20) DEFAULT '' NOT NULL,
                    Dept char(10) DEFAULT '' NOT NULL,
                    JobTitle char(20),
                    UNIQUE name_dept (Name,Dept)
                    );
mysql> CREATE UNIQUE index name_dept on employee (name,dept); - avoids duplicate keys
mysql> INSERT INTO employee VALUES ("Jane Smith","Sales","Customer Rep");
mysql> INSERT INTO employee VALUES ('Jane Smith','Sales','Account Manager');
mysql> INSERT INTO employee VALUES ('Jane Smith','Engineerin','Manager');
mysql> UPDATE employee SET dept='HR' WHERE name='Jane Smith';

Use "auto_increment" integer column:
   mysql> ALTER TABLE employee ADD EmpId INT NOT NULL AUTO_INCREMENT PRIMARY KEY; 

mysql> SHOW INDEX FROM employee;
mysql> ALTER TABLE employee DROP INDEX name_dept;  - get rid of 
mysql> SELECT VERSION();
mysql> SELECT NOW();
mysql> SELECT USER();
mysql> SELECT * FROM employee WHERE name LIKE "%Sm%";
mysql> SELECT * FROM employee WHERE name REGEXP "^Ja";
mysql>

See section 3 of MySQL manual for more examples.

Loading Data:

Command: LOAD DATA LOCAL INFILE 'file.dat' INTO TABLE employer;

Input tab delimited file: file.dat

Fred Flinstone  Quarry Worker   Rock Digger
Wilma Flinstone Finance Analyst 
Barney Rubble   Sales   Neighbor
Betty Rubble    IT      Neighbor

Dump/Backup/Transfer Database:

The mysqldump command will read the mySQL database and generate a SQL command text file. This allows data to be migrated to other versions of mySQL (i.e. upgrade from typical Red Hat (RH7.x to FC3) mySQL release 3.23.58 to a more advanced mySQL 4.1 or 5.0) or to other SQL databases. SQL command file generated can create tables, insert data, ....

Option	Description
-A --all-databases	Dump all the databases.
-B --databases	Dump the specified databases.
-h --host=	Specify host to connect to.
-p --password=	Specify password. If you do not specify a password, then you will be queried.
-u --user=	Specify user. Defaults to current user logged in.
--opt	Same as: --add-drop-table --add-locks --all --extended-insert --quick --lock-tables
--add-drop-table	Add a "drop table" SQL statement before each "create" SQL statement.
--add-locks	Add "lock" SQL statements around "insert" SQL statements.
-a --all	Include all mySQL specific SQL "create" options.
-e --extended-insert	Allows utilization of the new, much faster INSERT syntax. Database you are migrating to must support this notation.
-q --quick	Don’t buffer query, dump directly to stdout.
-l --lock-tables	Lock all tables for read.
-? --help	Display command line options.

Examples:

Dump database to a file:
- Dump specified database:
  mysqldump --opt database > db-dump-file.sql
- Dump specified table in database:
  mysqldump --opt database table-name > db-dump-file.sql
- Dump multiple databases:
  mysqldump --opt --databases database1 database2 database3 > db-dump-file.sql
- Dump everything:
  mysqldump --opt --all-databases > total-db-dump-file.sql
  mysqldump -u user-id -h host-name --opt --all-databases > total-db-dump-file.sql
[Potential Pitfall]: If you experience the following error:

mysqldump: Got error: 1016: Can't open file: 'Database-Name' (errno: 145) when using LOCK TABLES
Fix with the following command: mysqlcheck -r -u root -p Database-Name
Import dumped file:
mysql database < db-dump-file.sql
Export from one database and import to another:
- Transfer specifed database from one database to another:
  mysqldump --opt database | mysql --host=host-name -C database

Man Page:

mysqldump

Upgrading to 4.1:

Upgrading mySQL to 4.1 from 3.23
Use the command: mysql_fix_privilege_tables --password=root-password
This allows you to use the new GRANT command.

Restore MySql Database:

Restore using dump generated by mysqldump above:

mysql -h host-name -u user-id -psupersecretpassword < total-db-dump-file.sql
mysql database-name -h host-name -u user-id -psupersecretpassword < db-dump-file.sql

System Notes:

[Potential Pitfall]: Ubuntu mysql 5.0 database migration - When migrating the mysql database by copying files from /var/lib/mysql/... and /etc/mysql/... from one system running Ubuntu 6.11 to 8.04, I got nebulous error message in /var/log/syslog. The root cause of the problem was apparmor. If turing off apparmor (/etc/init.d/apparmor stop) allows your database to start and function properly, then go fix your apparmor security rules in /etc/apparmor.d/usr.sbin.mysqld. Also note that you must use the newer script /etc/mysql/debian-start from release 8.04 after copying /etc/mysql/....

Note: Debian and Ubuntu distributions manage mysql package upgrades using a mysql user debian-sys-maint which has its information located in /etc/mysql/debian.cnf. If you ever forget your mysql root password, you can always get back into the mysql database using the user debian-sys-maint and its password held in /etc/mysql/debian.cnf.

Building MySql from source: (on Linux)

Prerequisites:

C compiler: 2.95.2 or later. (Check with the command: rpm -q gcc)

Compile and install: (as root)

Downloaded source from http://dev.mysql.com/downloads/mysql/4.1.html
Expand tar file: tar xzf mysql-4.1.16.tar.gz
cd mysql-4.1.16
./configure --prefix=/opt/mysql --sysconfdir=/opt/etc --localstatedir=/opt/var/mysql --with-unix-socket-path=/opt/tmp/mysql.sock
(Use the command ./configure --help to see all options.)
This should create an installation which will not clobber an existing RPM mySQL installation.
make
make install
Create mysql config file: cp support-files/my-medium.cnf /opt/var/my.cnf
Create user/group mysql
- Test if user/group mysql already exists: groups mysql
- Create group: groupadd mysql
- Create user: useradd -g mysql -M -r -d /opt/lib/mysql -s /sbin/nologin -c "MySQL Server" mysql
chown -R mysql:mysql /opt/var/mysql

Configure:

Install default database: /opt/mysql/bin/mysql_install_db --user=mysql
Since this command is run as root, specify the --user option to operate command as user mysql.
Creates help database with SQL script: /opt/mysql/share/mysql/fill_help_tables.sql
Start mySQL database: /opt/mysql/bin/mysqld_safe --user=mysql &
/opt/mysql/bin/mysqladmin -u root password 'new-password'
/opt/mysql/bin/mysqladmin -u root -h yoserver2 password 'new-password'
See tutorial above for use and administration.

Check defaults: (Defaults from config file: /opt/var/my.cnf)

/opt/mysql/bin/my_print_defaults --config-file=my client mysql

--password=supersecret                    --port=3306                    --socket=/opt/tmp/mysql.sock                    --no-auto-rehash

/opt/mysql/bin/my_print_defaults --config-file=my client mysql mysql_install_db

--datadir=/var/lib/mysql
--socket=/var/lib/mysql/mysql.sock
--password=supersecret                    --port=3306                    --socket=/opt/tmp/mysql.sock                    --port=3306                    --socket=/opt/tmp/mysql.sock                    --skip-locking                    --key_buffer=16M                    --max_allowed_packet=1M                    --table_cache=64                    --sort_buffer_size=512K                    --net_buffer_length=8K                    --read_buffer_size=256K                    --read_rnd_buffer_size=512K                    --myisam_sort_buffer_size=8M                    --log-bin                    --server-id=1

Commands/Man pages:

isamchk - Check and repair of ISAM tables.
isamlog - Write info about whats in a nisam log file.
msql2mysql
my_print_defaults
myisamchk
myisamlog
myisampack
mysql - text-based client for mysqld, a SQL-based relational database daemon
mysql_config
mysql_convert_table_format
mysql_find_rows
mysql_fix_privilege_tables
mysql_install_db
mysql_setpermission
mysql_zap - a perl script used to kill processes
mysqlaccess - Create new users to mysql.
mysqlbinlog
mysqlbug
mysqlcheck
mysqld_multi - Used for managing several mysqld processes running in different UNIX sockets and TCP/IP ports.
mysqldump - text-based client for dumping or backing up mysql databases , tables and or data.
mysqldumpslow
mysqlhotcopy
mysqlimport
mysqlshow - Shows the structure of a mysql database (databases,tables and columns)
mysqltest
pack_isam
perror - used to display a description for a system error code, or an MyISAM/ISAM table handler error code.
replace - A utility program to replace changes strings in place in files or on the standard input.
resolve_stack_dump
resolveip

Server:

mysqladmin - A utility for performing administrative operations
safe_mysqld - The recommended way to start a mysqld daemon on Unix.

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