Check if and how swap file is used

free -m

Check if and how swap is used

set mysqldump to utf8

Have you tried adding

SET NAMES 'utf8';

to your sql dump?

The thing with utf8 or encodings in general is that in order to be successfull, you have to make sure that:

• the file is encoded utf8 without signature
• the default encoding of the mysql server is set to utf8
• the connection is utf8 (that's why you put SET NAMES 'utf8' into your sql-file).
• all tables and columns have the right encoding and charset
• all your webfiles have to be utf8 encoded as well. And it doesn't work to just add the correct header. You have to open the file, check if the encoding is utf8, if not, cut everything, change the encoding to utf8 and paste everything back. It doesn't work, if you just change the encoding and save the file!

How Do I Enable Remote Access To MySQL Database Server?

by NIX Craft on March 31, 2006 · 157 comments· LAST UPDATED July 20, 2013

in Linux, MySQL, UNIX

By default remote access to the MySQL database server is disabled for security reasons. However, some time you need to provide remote access to database server from home or a web server. This post will explain how to setup a user account and access mysql server remotely.

Task: MySQL Server Remote Access

You need type the following commands which will allow remote connections.

Step # 1: Login Using SSH (if server is outside your data center)

First, login over ssh to remote MySQL database server. You may need to login to your MySQL server as the root user:

ssh user@server1.cyberciti.biz
### login as the root using su or sudo ##
su
#sudo -s
 

OR directly login as root user:

ssh root@server1.cyberciti.biz

Step # 2: Edit the my.cnf file

Once connected you need to edit the MySQL server configuration file my.cnf using a text editor such as vi:

• If you are using Debian Linux file is located at /etc/mysql/my.cnf location.
• If you are using Red Hat Linux/Fedora/Centos Linux file is located at /etc/my.cnf location.
• If you are using FreeBSD you need to create a file /var/db/mysql/my.cnf location.

Edit the /etc/my.cnf, run:
# vi /etc/my.cnf

Step # 3: Once file opened, locate line that read as follows

[mysqld] 

Make sure line skip-networking is commented (or remove line) and add following line

bind-address=YOUR-SERVER-IP

For example, if your MySQL server IP is 65.55.55.2 then entire block should be look like as follows:

[mysqld]
user            = mysql
pid-file        = /var/run/mysqld/mysqld.pid
socket          = /var/run/mysqld/mysqld.sock
port            = 3306
basedir         = /usr
datadir         = /var/lib/mysql
tmpdir          = /tmp
language        = /usr/share/mysql/English
bind-address    = 65.55.55.2
# skip-networking
....
..
....

Where,

• bind-address: IP address to bind to.
• skip-networking : Don’t listen for TCP/IP connections at all. All interaction with mysqld must be made via Unix sockets. This option is highly recommended for systems where only local requests are allowed. Since you need to allow remote connection this line should be removed from my.cnf or put it in comment state.

Step# 4 Save and Close the file

If you are using Debian / Ubuntu Linux, type the following command to restart the mysql server:
# /etc/init.d/mysql restart
If you are using RHEL / CentOS / Fedora / Scientific Linux, type the following command to restart the mysql server:
# /etc/init.d/mysqld restart
If you are using FreeBSD, type the following command to restart the mysql server:
# /usr/local/etc/rc.d/mysql-server stop
# /usr/local/etc/rc.d/mysql-server start
OR
# /usr/local/etc/rc.d/mysql-server restart

Step # 5 Grant access to remote IP address

Connect to mysql server:
$ mysql -u root -p mysql

Grant access to a new database

If you want to add a new database called foo for user bar and remote IP 202.54.10.20 then you need to type the following commands at mysql> prompt:mysql> CREATE DATABASE foo;
mysql> GRANT ALL ON foo.* TO bar@'202.54.10.20' IDENTIFIED BY 'PASSWORD';

How Do I Grant Access To An Existing Database?

Let us assume that you are always making connection from remote IP called 202.54.10.20 for database called webdb for user webadmin, To grant access to this IP address type the following command At mysql> prompt for existing database, enter:
mysql> update db set Host='202.54.10.20' where Db='webdb';
mysql> update user set Host='202.54.10.20' where user='webadmin';

Step # 6: Logout of MySQL

Type exit command to logout mysql:mysql> exit

Step # 7: Open port 3306

You need to open TCP port 3306 using iptables or BSD pf firewall.

A sample iptables rule to open Linux iptables firewall

/sbin/iptables -A INPUT -i eth0 -p tcp --destination-port 3306 -j ACCEPT

OR only allow remote connection from your web server located at 10.5.1.3:

/sbin/iptables -A INPUT -i eth0 -s 10.5.1.3 -p tcp --destination-port 3306 -j ACCEPT

OR only allow remote connection from your lan subnet 192.168.1.0/24:

/sbin/iptables -A INPUT -i eth0 -s 192.168.1.0/24 -p tcp --destination-port 3306 -j ACCEPT

Finally save all rules (RHEL / CentOS specific command):
# service iptables save

A sample FreeBSD / OpenBSD pf rule ( /etc/pf.conf)

pass in on $ext_if proto tcp from any to any port 3306

OR allow only access from your web server located at 10.5.1.3:

pass in on $ext_if proto tcp from 10.5.1.3 to any port 3306  flags S/SA synproxy state

Step # 8: Test it

From your remote system or your desktop type the following command:
$ mysql -u webadmin –h 65.55.55.2 –p
Where,

• -u webadmin: webadmin is MySQL username
• -h IP or hostname: 65.55.55.2 is MySQL server IP address or hostname (FQDN)
• -p : Prompt for password

You can also use the telnet or nc command to connect to port 3306 for testing purpose:
$ echo X | telnet -e X 65.55.55.2 3306
OR
$ nc -z -w1 65.55.55.2 3306
Sample outputs:

Connection to 65.55.55.2 3306 port [tcp/mysql] succeeded!

create and last update timestamp fields on mysql

As of MySQL 5.6 its easy-peasy... give it a try:

create table tweet ( 
    id integer not null auto_increment primary key, 
    stamp_created timestamp default now(), 
    stamp_updated timestamp default now() on update now(),
    message varchar(163)
)

or 

 

  `inserted` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `insert_src_ver_id` INT NULL,
  `updated` TIMESTAMP NULL ON UPDATE CURRENT_TIMESTAMP,
  `update_src_ver_id` INT NULL,

for MySQL 5.5 or older 

First define them like this:
CREATE TABLE `entity` ( `entityid` int(11) NOT NULL AUTO_INCREMENT, `createDate` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00', `lastModified` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00', `name` varchar(255) DEFAULT NULL, `comment` text, PRIMARY KEY (`entityid`), ) Then add these triggers:
DELIMITER ;; CREATE trigger entityinsert BEFORE INSERT ON entity FOR EACH ROW BEGIN SET NEW.createDate=IF(ISNULL(NEW.createDate) OR NEW.createDate='0000-00-00 00:00:00', CURRENT_TIMESTAMP, IF(NEW.createDate<CURRENT_TIMESTAMP, NEW.createDate, CURRENT_TIMESTAMP));SET NEW.lastModified=NEW.createDate; END;; DELIMITER ; CREATE trigger entityupdate BEFORE UPDATE ON entity FOR EACH ROW SET NEW.lastModified=IF(NEW.lastModified<OLD.lastModified, OLD.lastModified, CURRENT_TIMESTAMP);

• If you insert without specifying createDate or lastModified, they will be equal and set to the current timestamp.
• If you update them without specifying createDate or lastModified, the lastModified will be set to the current timestamp.

But here's the nice part:

• If you insert, you can specify a createDate older than the current timestamp, allowing imports from older times to work well (lastModified will be equal to createDate).
• If you update, you can specify a lastModified older than the previous value ('0000-00-00 00:00:00' works well), allowing to update an entry if you're doing cosmetic changes (fixing a typo in a comment) and you want to keep the old lastModified date. This will not modify the lastModified date.

 

วิธีแก้ MySQL ใน Ubuntu Linux ให้รองรับภาษาไทยได้

ต้องแก้  /etc/my.cnf โดยเพิ่มตามข้างล่างนี้

To set the default to UTF-8, you want to add the following to my.cnf

[client]
default-character-set=utf8

[mysql]
default-character-set=utf8


[mysqld]
collation-server = utf8_unicode_ci
init-connect='SET NAMES utf8'
character-set-server = utf8

How to install Gnome on Debian 6 minimally

Install Debian 6 from installation CD
Choose only Standard System Utilities.  Uncheck Graphical Desktop Environment
Reboot and logon after installation finish

apt-get install xserver-xorg-input-kbd xserver-xorg-input-vmmouse xserver-xorg-video-vmware

Use virtualenv to manage multiple version of python on linux

virtualenv can switch between multiple python version and addon.

Use pip to install additional python packages in each python environment

virtualenv -p /usr/bin/python3 py3env
source py3env/bin/activate
pip install package-name