Thursday, May 19, 2016

MySQL commands for Database Administration in Linux



1. How to set MySQL Root password?

If you have fresh installation of MySQL server, then it doesn’t required any password to connect it as root user. To set MySQL password for root user, use the following command.

# mysqladmin -u root password YOURNEWPASSWORD


2. How to Change MySQL Root password?

If you would like to change or update MySQL root password, then you need to type the following command. For example, say your old password is 123456 and you want to change it with new password say xyz123.

mysqladmin -u root -p123456 password 'xyz123'


3. How to check MySQL Server is running?

To find out whether MySQL server is up and running, use the following command.

# mysqladmin -u root -p ping

Enter password:
mysqld is alive


4. How to Check which MySQL version I am running?

The following command shows MySQL version along with the current running status .

# mysqladmin -u root -p version

Enter password:
mysqladmin  Ver 8.42 Distrib 5.5.28, for Linux on i686
Copyright (c) 2000, 2012, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Server version          5.5.28
Protocol version        10
Connection              Localhost via UNIX socket
UNIX socket             /var/lib/mysql/mysql.sock
Uptime:                 7 days 14 min 45 sec

Threads: 2  Questions: 36002  Slow queries: 0  Opens: 15  Flush tables: 1  Open tables: 8  Queries per second avg: 0.059


5. How to Find out current Status of MySQL server?

To find out current status of MySQL server, use the following command. The mysqladmin command shows the status of uptime with running threads and queries.

# mysqladmin -u root -ptmppassword status

Enter password:
Uptime: 606704  Threads: 2  Questions: 36003  Slow queries: 0  Opens: 15  Flush tables: 1  Open tables: 8  Queries per second avg: 0.059


6. How to check status of all MySQL Server Variable’s and value’s?

To check all the running status of MySQL server variables and values, type the following command. The output would be similar to below.

# mysqladmin -u root -p extended-status

Enter password:
+------------------------------------------+-------------+
| Variable_name                            | Value       |
+------------------------------------------+-------------+
| Aborted_clients                          | 3           |
| Aborted_connects                         | 3           |
| Binlog_cache_disk_use                    | 0           |
| Binlog_cache_use                         | 0           |
| Binlog_stmt_cache_disk_use               | 0           |
| Binlog_stmt_cache_use                    | 0           |
| Bytes_received                           | 6400357     |
| Bytes_sent                               | 2610105     |
| Com_admin_commands                       | 3           |
| Com_assign_to_keycache                   | 0           |
| Com_alter_db                             | 0           |
| Com_alter_db_upgrade                     | 0           |
| Com_alter_event                          | 0           |
| Com_alter_function                       | 0           |
| Com_alter_procedure                      | 0           |
| Com_alter_server                         | 0           |
| Com_alter_table                          | 0           |
| Com_alter_tablespace                     | 0           |
+------------------------------------------+-------------+


7. How to see all MySQL server Variables and Values?

To see all the running variables and values of MySQL server, use the command as follows.

# mysqladmin  -u root -p variables

Enter password:
+---------------------------------------------------+----------------------------------------------+
| Variable_name                                     | Value                                        |
+---------------------------------------------------+----------------------------------------------+
| auto_increment_increment                          | 1                                            |
| auto_increment_offset                             | 1                                            |
| autocommit                                        | ON                                           |
| automatic_sp_privileges                           | ON                                           |
| back_log                                          | 50                                           |
| basedir                                           | /usr                                         |
| big_tables                                        | OFF                                          |
| binlog_cache_size                                 | 32768                                        |
| binlog_direct_non_transactional_updates           | OFF                                          |
| binlog_format                                     | STATEMENT                                    |
| binlog_stmt_cache_size                            | 32768                                        |
| bulk_insert_buffer_size                           | 8388608                                      |
| character_set_client                              | latin1                                       |
| character_set_connection                          | latin1                                       |
| character_set_database                            | latin1                                       |
| character_set_filesystem                          | binary                                       |
| character_set_results                             | latin1                                       |
| character_set_server                              | latin1                                       |
| character_set_system                              | utf8                                         |
| character_sets_dir                                | /usr/share/mysql/charsets/                   |
| collation_connection                              | latin1_swedish_ci                            |
+---------------------------------------------------+----------------------------------------------+



8. How to check all the running Process of MySQL server?

The following command will display all the running process of MySQL database queries.

# mysqladmin -u root -p processlist

Enter password:
+-------+---------+-----------------+---------+---------+------+-------+------------------+
| Id    | User    | Host            | db      | Command | Time | State | Info             |
+-------+---------+-----------------+---------+---------+------+-------+------------------+
| 18001 | rsyslog | localhost:38307 | rsyslog | Sleep   | 5590 |       |                  |
| 18020 | root    | localhost       |         | Query   | 0    |       | show processlist |
+-------+---------+-----------------+---------+---------+------+-------+------------------+



9. How to create a Database in MySQL server?

To create a new database in MySQL server, use the command as shown below.

# mysqladmin -u root -p create databasename

Enter password:

# mysql -u root -p

Enter password:
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 18027
Server version: 5.5.28 MySQL Community Server (GPL) by Remi

Copyright (c) 2000, 2012, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| databasename       |
| mysql              |
| test               |
+--------------------+
8 rows in set (0.01 sec)

mysql>



10. How to drop a Database in MySQL server?

To drop a Database in MySQL server, use the following command. You will be asked to confirm press ‘y‘.

# mysqladmin -u root -p drop databasename

Enter password:
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 'databasename' database [y/N] y
Database "databasename" dropped



11. How to reload/refresh MySQL Privileges?

The reload command tells the server to reload the grant tables. The refresh command flushes all tables and reopens the log files.

# mysqladmin -u root -p reload;
# mysqladmin -u root -p refresh



12. How to shutdown MySQL server Safely?

To shutdown MySQL server safely, type the following command.

mysqladmin -u root -p shutdown

Enter password:

You can also use the following commands to start/stop MySQL server.

# /etc/init.d/mysqld stop
# /etc/init.d/mysqld start



13. Some useful MySQL Flush commands

Following are some useful flush commands with their description.

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

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



14. How to kill Sleeping MySQL Client Process?

Use the following command to identify sleeping MySQL client process.

# mysqladmin -u root -p processlist

Enter password:
+----+------+-----------+----+---------+------+-------+------------------+
| Id | User | Host      | db | Command | Time | State | Info             |
+----+------+-----------+----+---------+------+-------+------------------+
| 5  | root | localhost |    | Sleep   | 14   |       |                                                                      |
| 8  | root | localhost |    | Query   | 0    |       | show processlist |
+----+------+-----------+----+---------+------+-------+------------------+

Now, run the following command with kill and process ID as shown below.

# mysqladmin -u root -p kill 5

Enter password:
+----+------+-----------+----+---------+------+-------+------------------+
| Id | User | Host      | db | Command | Time | State | Info             |
+----+------+-----------+----+---------+------+-------+------------------+
| 12 | root | localhost |    | Query   | 0    |       | show processlist |
+----+------+-----------+----+---------+------+-------+------------------+

If you like to kill multiple process, then pass the process ID‘s with comma separated as shown below.

# mysqladmin -u root -p kill 5,10



15. How to run multiple mysqladmin commands together?

If you would like to execute multiple ‘mysqladmin‘ commands together, then the command would be like this.

# mysqladmin  -u root -p processlist status version

Enter password:
+----+------+-----------+----+---------+------+-------+------------------+
| Id | User | Host      | db | Command | Time | State | Info             |
+----+------+-----------+----+---------+------+-------+------------------+
| 8  | root | localhost |    | Query   | 0    |       | show processlist |
+----+------+-----------+----+---------+------+-------+------------------+
Uptime: 3801  Threads: 1  Questions: 15  Slow queries: 0  Opens: 15  Flush tables: 1  Open tables: 8  Queries per second avg: 0.003
mysqladmin  Ver 8.42 Distrib 5.5.28, for Linux on i686
Copyright (c) 2000, 2012, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Server version          5.5.28
Protocol version        10
Connection              Localhost via UNIX socket
UNIX socket             /var/lib/mysql/mysql.sock
Uptime:                 1 hour 3 min 21 sec

Threads: 1  Questions: 15  Slow queries: 0  Opens: 15  Flush tables: 1  Open tables: 8  Queries per second avg: 0.003



16. How to Connect remote mysql server

To connect remote MySQL server, use the -h (host)  with IP Address of remote machine.

# mysqladmin  -h 172.16.25.126 -u root -p



17. How to execute command on remote MySQL server

Let’s say you would like to see the status of remote MySQL server, then the command would be.

# mysqladmin  -h 172.16.25.126 -u root -p status



18. How to start/stop MySQL replication on a slave server?

To start/stop MySQL replication on salve server, use the following commands.

# mysqladmin  -u root -p start-slave

# mysqladmin  -u root -p stop-slave



19. How to store MySQL server Debug Information to logs?

It tells the server to write debug information about locks in use, used memory and query usage to the MySQL log file including information about event scheduler.

# mysqladmin  -u root -p debug

Enter password:



20. How to view mysqladmin options and usage

To find out more options and usage of myslqadmin command use the help command as shown below. It will display a list of available options.

# mysqladmin --help


How to install Asterisk on CentOS 7.X

In this installment of our How To, we are going to go over on the topic of how to install Asterisk on CentOS. For this we are going to use Asterisk 13 and CentOS 7 minimal version. But, instructions will mostly be similar to other versions of Asterisk and CentOS.

As a first step you need to download latest asterisk on to your machine. For this you need wget tool. As we are using minimal flavor of CentOS even wget tool is not available on fresh install. Run the following command to install wget.

Steps : 1

#yum install wget

Once, wget is installed successfully, run the following command to download asterisk.

wget http://downloads.asterisk.org/pub/telephony/asterisk/asterisk-13-current.tar.gz

Extract downloaded asterisk tar ball

tar -zxvf asterisk-13-current.tar.gz
cd asterisk-13.6.0

Install the following dependencies
Step:2

yum install gcc
yum install gcc-c++
yum install ncurses-devel
yum install uuid-devel libuuid-devel
yum install jansson-devel
yum install libxml2-devel
yum install sqlite-devel

Once, all the above dependencies are installed. You can now run the following command to enable or disable modules of your choice.

make menuselect

After you are done with the menu select screen, run the following command to compile and install asterisk
Step : 3

make
make install
make samples


That’s it now you have asterisk installed successfully on your you machine. Run, the following command to start asterisk
asterisk –vvvvgc

Now, you should see asterisk console saying “Asterisk Ready”. Instead, if you encounter the following error
/usr/bin/asterisk: error while loading shared libraries: libasteriskssl.so.1: cannot open shared object file: no such file or directory.

Don’t worry, just run the following command and start asterisk again after that.
ldconfig


That’s of all enjoy it

MySQL Backup and Restore Commands for Database Administration

How to Backup MySQL Database?

To take a backup of MySQL database or databases, the database must exist in the database server and you must have access to it. The format of the command would be.

# mysqldump -u [username] –p[password] [database_name] > [dump_file.sql]

The parameters of the said command as follows.
  1. [username] : A valid MySQL username.
  2. [password] : A valid MySQL password for the user.
  3. [database_name] : A valid Database name you want to take backup.
  4. [dump_file.sql] : The name of backup dump file you want to generate.
How to Backup a Single MySQL Database?

To take a backup of single database, use the command as follows. The command will dump database [rsyslog] structure with data on to a single dump file called rsyslog.sql.

# mysqldump -u root -pgolden rsyslog > rsyslog.sql


How to Backup Multiple MySQL Databases?

If you want to take backup of multiple databases, run the following command. The following example command takes a backup of databases [rsyslog, syslog] structure and data in to a single file called rsyslog_syslog.sql.

# mysqldump -u root -pgolden --databases rsyslog syslog > rsyslog_syslog.sql

How to Backup All MySQL Databases?

If you want to take backup of all databases, then use the following command with option –all-database. The following command takes the backup of all databases with their structure and data into a file called all-databases.sql.

# mysqldump -u root -pgolden --all-databases > all-databases.sql

How to Backup MySQL Database Structure Only?

If you only want the backup of database structure without data, then use the option –no-data in the command. The below command exports database [rsyslog] Structure into a file 
rsyslog_structure.sql.

# mysqldump -u root -pgolden -–no-data rsyslog > rsyslog_structure.sql

How to Backup MySQL Database Data Only?

To backup database Data only without structure, then use the option –no-create-info with the command. This command takes the database [rsyslog] Data  into a file rsyslog_data.sql.

# mysqldump -u root -pgolden --no-create-db --no-create-info rsyslog > 
rsyslog_data.sql

How to Backup Single Table of Database?

With the below command you can take backup of single table or certain tables of your database. For example, the following command only take backup of wp_posts table from the database wordpress.

# mysqldump -u root -pgolden wordpress wp_posts > wordpress_posts.sql

How to Backup Multiple Tables of Database?

If you want to take backup of multiple or certain tables from the database, then separate each table with space.

# mysqldump -u root -pgolden wordpress wp_posts wp_comments > wordpress_posts_comments.sql

How to Backup Remote MySQL Database

The below command takes the backup of remote server [172.16.25.126] database [gallery] into a 
local server.

# mysqldump -h 172.16.25.126 -u root -pgolden gallery > gallery.sql

How to Restore MySQL Database?

In the above tutorial we have seen the how to take the backup of databases, tables, structures and data only, now we will see how to restore them using following format.

# # mysql -u [username] –p[password] [database_name] < [dump_file.sql]

How to Restore Single MySQL Database

To restore a database, you must create an empty database on the target machine and restore the database using msyql command. For example the following command will restore the rsyslog.sql file to the rsyslog database.

# mysql -u root -pgolden rsyslog < rsyslog.sql

If you want to restore a database that already exist on targeted machine, then you will need to use the 
mysqlimport command.

# mysqlimport -u root -pgolden rsyslog < rsyslog.sql

That of all enjoy the Database backup concepts