MySQL Admin Command Practical Usages For Administering MySQL Server

In all the 15 mysqladmin command-line examples below, tmppassword is used as the MySQL root user password. Please change this to your MySQL root password.

1. How to change the MySQL root user password?

# mysqladmin -u root -ptmppassword password 'newpassword'

# mysql -u root -pnewpassword
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 8
Server version: 5.1.25-rc-community MySQL Community Server (GPL)

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

mysql>

2. How to check whether MySQL Server is up and running? 

# mysqladmin -u root -p ping Enter password: mysqld is alive

3. How do I find out what version of MySQL I am running?

Apart from giving the ‘Server version’, this command also displays the current status of the mysql server.

# mysqladmin -u root -ptmppassword version
mysqladmin  Ver 8.42 Distrib 5.1.25-rc, for redhat-linux-gnu on i686
Copyright (C) 2000-2006 MySQL AB
This software comes with ABSOLUTELY NO WARRANTY. This is free software,
and you are welcome to modify and redistribute it under the GPL license

Server version          5.1.25-rc-community
Protocol version        10
Connection              Localhost via UNIX socket
UNIX socket             /var/lib/mysql/mysql.sock
Uptime:                 107 days 6 hours 11 min 44 sec

Threads: 1  Questions: 231976  Slow queries: 0  Opens: 17067
Flush tables: 1  Open tables: 64  Queries per second avg: 0.25

4. What is the current status of MySQL server?

# mysqladmin -u root -ptmppassword status
Uptime: 9267148
Threads: 1  Questions: 231977  Slow queries: 0  Opens: 17067
Flush tables: 1  Open tables: 64  Queries per second avg: 0.25

The status command displays the following information:

• Uptime: Uptime of the mysql server in seconds
• Threads: Total number of clients connected to the server.
• Questions: Total number of queries the server has executed since the startup.
• Slow queries: Total number of queries whose execution time waas more than long_query_time variable’s value.
• Opens: Total number of tables opened by the server.
• Flush tables: How many times the tables were flushed.
• Open tables: Total number of open tables in the database.

5. How to view all the MySQL Server status variable and it’s current value?

# mysqladmin -u root -ptmppassword extended-status
+-----------------------------------+-----------+
| Variable_name                     | Value     |
+-----------------------------------+-----------+
| Aborted_clients                   | 579       |
| Aborted_connects                  | 8         |
| Binlog_cache_disk_use             | 0         |
| Binlog_cache_use                  | 0         |
| Bytes_received                    | 41387238  |
| Bytes_sent                        | 308401407 |
| Com_admin_commands                | 3524      |
| Com_assign_to_keycache            | 0         |
| Com_alter_db                      | 0         |
| Com_alter_db_upgrade              | 0         |

6. How to display all MySQL server system variables and the values?

# mysqladmin  -u root -ptmppassword variables
+---------------------------------+---------------------------------+
| Variable_name                   | Value                           |
+---------------------------------+---------------------------------+
| auto_increment_increment        | 1                               |
| basedir                         | /                               |
| big_tables                      | OFF                             |
| binlog_format                   | MIXED                           |
| bulk_insert_buffer_size         | 8388608                         |
| character_set_client            | latin1                          |
| character_set_database          | latin1                          |
| character_set_filesystem        | binary                          |

skip.....

| time_format                     | %H:%i:%s                        |
| time_zone                       | SYSTEM                          |
| timed_mutexes                   | OFF                             |
| tmpdir                          | /tmp                            |
| tx_isolation                    | REPEATABLE-READ                 |
| unique_checks                   | ON                              |
| updatable_views_with_limit      | YES                             |
| version                         | 5.1.25-rc-community             |
| version_comment                 | MySQL Community Server (GPL)    |
| version_compile_machine         | i686                            |
| version_compile_os              | redhat-linux-gnu                |
| wait_timeout                    | 28800                           |
+---------------------------------+---------------------------------+

7. How to display all the running process/queries in the mysql database?

# mysqladmin -u root -ptmppassword processlist
+----+------+-----------+----+---------+------+-------+------------------+
| Id | User | Host      | db | Command | Time | State | Info             |
+----+------+-----------+----+---------+------+-------+------------------+
| 20 | root | localhost |    | Sleep   | 36   |       |                  |
| 23 | root | localhost |    | Query   | 0    |       | show processlist |
+----+------+-----------+----+---------+------+-------+------------------+

You can use this command effectively to debug any performance issue and identify the query that is causing problems, by running the command automatically every 1 second as shown below.

# mysqladmin -u root -ptmppassword -i 1 processlist
+----+------+-----------+----+---------+------+-------+------------------+
| Id | User | Host      | db | Command | Time | State | Info             |
+----+------+-----------+----+---------+------+-------+------------------+
| 20 | root | localhost |    | Sleep   | 36   |       |                  |
| 23 | root | localhost |    | Query   | 0    |       | show processlist |
+----+------+-----------+----+---------+------+-------+------------------+

+----+------+-----------+----+---------+------+-------+------------------+
| Id | User | Host      | db | Command | Time | State | Info             |
+----+------+-----------+----+---------+------+-------+------------------+
| 24 | root | localhost |    | Query   | 0    |       | show processlist |
+----+------+-----------+----+---------+------+-------+------------------+

8. How to create a MySQL Database?

# mysqladmin -u root -ptmppassword create testdb

# mysql -u root -ptmppassword
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 705
Server version: 5.1.25-rc-community MySQL Community Server (GPL)

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| sugarcrm           |
| testdb             |
+--------------------+
4 rows in set (0.00 sec)

Note: To display all tables in a database, total number of columns, row, column types, indexes etc., use the mysqlshow command that we discussed in our previous articles.

9. How to Delete/Drop an existing MySQL database?

# mysqladmin -u root -ptmppassword drop testdb
Dropping the database is potentially a very bad thing to do.
Any data stored in the database will be destroyed.

Do you really want to drop the 'testdb' database [y/N] y
Database "testdb" dropped

# mysql -u root -ptmppassword
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 707
Server version: 5.1.25-rc-community MySQL Community Server (GPL)

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| sugarcrm           |
+--------------------+
3 rows in set (0.00 sec)

10. How to reload/refresh the privilege or the grants tables?

# mysqladmin -u root -ptmppassword reload;

Refresh command will flush all the tables and close/open log files.

# mysqladmin -u root -ptmppassword refresh

11. What is the safe method to shutdown the MySQL server?

# mysqladmin -u root -ptmppassword shutdown

# mysql -u root -ptmppassword
ERROR 2002 (HY000): Can't connect to local MySQL server
through socket '/var/lib/mysql/mysql.sock'

Note: You can also use “/etc/rc.d/init.d/mysqld stop” to shutdown the server. To start the server, execute “/etc/rc.d/init.d/mysql start”

12. List of all mysqladmin flush commands.

# mysqladmin -u root -ptmppassword flush-hosts
# mysqladmin -u root -ptmppassword flush-logs
# mysqladmin -u root -ptmppassword flush-privileges
# mysqladmin -u root -ptmppassword flush-status
# mysqladmin -u root -ptmppassword flush-tables
# mysqladmin -u root -ptmppassword flush-threads

• flush-hosts: Flush all information in the host cache.
• flush-privileges: Reload the grant tables (same as reload).
• flush-status: Clear status variables.
• flush-threads: Flush the thread cache.

13. How to kill a hanging MySQL Client Process?

First identify the hanging MySQL client process using the processlist command.

# mysqladmin -u root -ptmppassword processlist
+----+------+-----------+----+---------+------+-------+------------------+
| Id | User | Host      | db | Command | Time | State | Info             |
+----+------+-----------+----+---------+------+-------+------------------+
| 20 | root | localhost |    | Sleep   | 64   |       |                  |
| 24 | root | localhost |    | Query   | 0    |       | show processlist |
+----+------+-----------+----+---------+------+-------+------------------+

Now, use the kill command and pass the process_id as shown below. To kill multiple process you can pass comma separated process id’s.

# mysqladmin -u root -ptmppassword kill 20

# mysqladmin -u root -ptmppassword processlist
+----+------+-----------+----+---------+------+-------+------------------+
| Id | User | Host      | db | Command | Time | State | Info             |
+----+------+-----------+----+---------+------+-------+------------------+
| 26 | root | localhost |    | Query   | 0    |       | show processlist |
+----+------+-----------+----+---------+------+-------+------------------+

14. How to start and stop MySQL replication on a slave server?

# mysqladmin  -u root -ptmppassword stop-slave
Slave stopped

# mysqladmin  -u root -ptmppassword start-slave
mysqladmin: Error starting slave: The server is not configured as slave;
fix in config file or with CHANGE MASTER TO

15. How to combine multiple mysqladmin commands together?

In the example below, you can combine process-list, status and version command to get all the output together as shown below.

# mysqladmin  -u root -ptmppassword process status version
+----+------+-----------+----+---------+------+-------+------------------+
| Id | User | Host      | db | Command | Time | State | Info             |
+----+------+-----------+----+---------+------+-------+------------------+
| 43 | root | localhost |    | Query   | 0    |       | show processlist |
+----+------+-----------+----+---------+------+-------+------------------+

Uptime: 3135
Threads: 1  Questions: 80  Slow queries: 0  Opens: 15  Flush tables: 3
Open tables: 0  Queries per second avg: 0.25

mysqladmin  Ver 8.42 Distrib 5.1.25-rc, for redhat-linux-gnu on i686
Copyright (C) 2000-2006 MySQL AB
This software comes with ABSOLUTELY NO WARRANTY. This is free software,
and you are welcome to modify and redistribute it under the GPL license

Server version          5.1.25-rc-community
Protocol version        10
Connection              Localhost via UNIX socket
UNIX socket             /var/lib/mysql/mysql.sock
Uptime:                 52 min 15 sec

You can also use the short form as shown below:

# mysqladmin  -u root -ptmppassword pro stat ver

Use the option -h, to connect to a remote MySQL server and execute the mysqladmin commands as shown below.

# mysqladmin  -h 192.168.1.112 -u root -ptmppassword pro stat ver

Securing MySQL Server with MySQL Secure Installation

This program enables you to improve the security of your MySQL installation in the following ways:

• You can set a password for root accounts.
• You can remove root accounts that are accessible from outside the local host.
• You can remove anonymous-user accounts.
• You can remove the test database (which by default can be accessed by all users, even anonymous users), and privileges that permit anyone to access databases with names that start with test_.

Before executing the following command, start the MySQL server.

[root@localhost ~]# service mysqld restart

Execute the following command to start MySQL configuration for the first time.

[root@localhost ~]# mysql_secure_installation
NOTE: RUNNING ALL PARTS OF THIS SCRIPT IS RECOMMENDED FOR ALL MySQL
SERVERS IN PRODUCTION USE!  PLEASE READ EACH STEP CAREFULLY!
In order to log into MySQL to secure it, we’ll need the current
password for the root user.  If you’ve just installed MySQL, and
you haven’t set the root password yet, the password will be blank,
so you should just press enter here.
Enter current password for root (enter for none): <—- Simply just enter because no password is set
OK, successfully used password, moving on…
Setting the root password ensures that nobody can log into the MySQL
root user without the proper authorisation.
Set root password? [Y/n]   <— Type Y and Enter for setting up the root password
New password:  <—- Type new password and Enter
Re-enter new password:  <—- Re-Type new password and Enter
Password updated successfully!
Reloading privilege tables..
… Success!
By default, a MySQL installation has an anonymous user, allowing anyone
to log into MySQL without having to have a user account created for
them.  This is intended only for testing, and to make the installation
go a bit smoother.  You should remove them before moving into a
production environment.
Remove anonymous users? [Y/n]   <—- Type Y to Remove anonymous user and press Enter
… Success!
Normally, root should only be allowed to connect from ‘localhost’.  This
ensures that someone cannot guess at the root password from the network.
Disallow root login remotely? [Y/n]  <—- Type Y to disable root login remotely and press Enter
… Success!
By default, MySQL comes with a database named ‘test’ that anyone can
access.  This is also intended only for testing, and should be removed
before moving into a production environment.
Remove test database and access to it? [Y/n]   <—- Type Y to remove test database and press Enter
- Dropping test database…
… Success!
- Removing privileges on test database…
… Success!
Reloading the privilege tables will ensure that all changes made so far
will take effect immediately.
Reload privilege tables now? [Y/n]   <—- Type Y to save the changes and press Enter
… Success!
Cleaning up…
All done!  If you’ve completed all of the above steps, your MySQL
installation should now be secure.
Thanks for using MySQL!

MySQL Database Backup and Restore Using mysqldump

mysqldump is an effective tool to backup MySQL database. It creates a *.sql file with DROP table, CREATE table and INSERT into sql-statements of the source database. To restore the database,  execute the *.sql file on destination database.  For MyISAM, use mysqlhotcopy method that we explained earlier, as it is faster for MyISAM tables.

Using mysqldump, you can backup a local database and restore it on a remote database at the same time, using a single command. In this article, let us review several practical examples on how to use mysqldump to backup and restore.

For the impatient, here is the quick snippet of how backup and restore MySQL database using mysqldump:

backup: # mysqldump -u root -p[root_password] [database_name] > dumpfilename.sql

restore:# mysql -u root -p[root_password] [database_name] < dumpfilename.sql

How To Backup MySQL database  

1. Backup a single database:

This example takes a backup of sugarcrm database and dumps the output to sugarcrm.sql

# mysqldump -u root -ptmppassword sugarcrm > sugarcrm.sql

# mysqldump -u root -p[root_password] [database_name] > dumpfilename.sql

The sugarcrm.sql will contain drop table, create table and insert command for all the tables in the sugarcrm database. Following is a partial output of sugarcrm.sql, showing the dump information of accounts_contacts table:

--
-- Table structure for table `accounts_contacts`
--

DROP TABLE IF EXISTS `accounts_contacts`;
SET @saved_cs_client     = @@character_set_client;
SET character_set_client = utf8;
CREATE TABLE `accounts_contacts` (
`id` varchar(36) NOT NULL,
`contact_id` varchar(36) default NULL,
`account_id` varchar(36) default NULL,
`date_modified` datetime default NULL,
`deleted` tinyint(1) NOT NULL default '0',
PRIMARY KEY  (`id`),
KEY `idx_account_contact` (`account_id`,`contact_id`),
KEY `idx_contid_del_accid` (`contact_id`,`deleted`,`account_id`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;
SET character_set_client = @saved_cs_client;

--
-- Dumping data for table `accounts_contacts`
--

LOCK TABLES `accounts_contacts` WRITE;
/*!40000 ALTER TABLE `accounts_contacts` DISABLE KEYS */;
INSERT INTO `accounts_contacts` VALUES ('6ff90374-26d1-5fd8-b844-4873b2e42091',
'11ba0239-c7cf-e87e-e266-4873b218a3f9','503a06a8-0650-6fdd-22ae-4873b245ae53',
'2008-07-23 05:24:30',1),
('83126e77-eeda-f335-dc1b-4873bc805541','7c525b1c-8a11-d803-94a5-4873bc4ff7d2',
'80a6add6-81ed-0266-6db5-4873bc54bfb5','2008-07-23 05:24:30',1),
('4e800b97-c09f-7896-d3d7-48751d81d5ee','f241c222-b91a-d7a9-f355-48751d6bc0f9',
'27060688-1f44-9f10-bdc4-48751db40009','2008-07-23 05:24:30',1),
('c94917ea-3664-8430-e003-487be0817f41','c564b7f3-2923-30b5-4861-487be0f70cb3',
'c71eff65-b76b-cbb0-d31a-487be06e4e0b','2008-07-23 05:24:30',1),
('7dab11e1-64d3-ea6a-c62c-487ce17e4e41','79d6f6e5-50e5-9b2b-034b-487ce1dae5af',
'7b886f23-571b-595b-19dd-487ce1eee867','2008-07-23 05:24:30',1);
/*!40000 ALTER TABLE `accounts_contacts` ENABLE KEYS */;
UNLOCK TABLES;

2. Backup multiple databases:

If you want to backup multiple databases, first identify the databases that you want to backup using the show databases as shown below:

# mysql -u root -ptmppassword

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| bugs               |
| mysql              |
| sugarcr            |
+--------------------+
4 rows in set (0.00 sec)

For example, if you want to take backup of both sugarcrm and bugs database, execute the mysqldump as shown below:

# mysqldump -u root -ptmppassword --databases bugs sugarcrm > bugs_sugarcrm.sql

Verify the bugs_sugarcrm.sql dumpfile contains both the database backup.

# grep -i "Current database:" /tmp/bugs_sugarcrm.sql
-- Current Database: `mysql`
-- Current Database: `sugarcrm`

3. Backup all the databases:

The following example takes a backup of  all the database of the MySQL instance.

# mysqldump -u root -ptmppassword --all-databases > /tmp/all-database.sql

4. Backup a specific table:

In this example, we backup only the accounts_contacts table from sugarcrm database.

# mysqldump -u root -ptmppassword sugarcrm accounts_contacts \
      > /tmp/sugarcrm_accounts_contacts.sql

4. Different mysqldump group options:

• –opt is a group option, which is same as –add-drop-table, –add-locks, –create-options, –quick, –extended-insert, –lock-tables, –set-charset, and –disable-keys. opt is enabled by default, disable with –skip-opt.
• –compact is a group option, which gives less verbose output (useful for debugging). Disables structure comments and header/footer constructs. Enables options –skip-add-drop-table –no-set-names –skip-disable-keys –skip-add-locks

How To Restore MySQL database

1. Restore a database

In this example, to restore the sugarcrm database, execute mysql with < as shown below. When you are restoring the dumpfilename.sql on a remote database, make sure to create the sugarcrm database before you can perform the restore.

# mysql -u root -ptmppassword

mysql> create database sugarcrm;
Query OK, 1 row affected (0.02 sec)

# mysql -u root -ptmppassword sugarcrm < /tmp/sugarcrm.sql

# mysql -u root -p[root_password] [database_name] < dumpfilename.sql

2. Backup a local database and restore to remote server using single command:

This is a sleek option, if you want to keep a read-only database on the remote-server, which is a copy of the master database on local-server. The example below will backup the sugarcrm database on the local-server and restore it as sugarcrm1 database on the remote-server. Please note that you should first create the sugarcrm1 database on the remote-server before executing the following command.

[local-server]# mysqldump -u root -ptmppassword sugarcrm | mysql \
                 -u root -ptmppassword --host=remote-server -C sugarcrm1
[Note: There are two -- (hyphen) in front of host]