Tuesday, February 25, 2014

Managing PostgreSQL with pgsql and pgAdmin3

The command line interface (CLI) tool that comes with Postgres server is known as pgsql. Alternatively, pgAdmin3 and phpPgAdmin can be installed.

The pgsql

Among some of the commands for pgsql can be shown as below;





pgAdmin3




Installing PostgreSQL on Centos 6

PostgreSQL being an OSS licensed database is very different compared to MySQL. PostgreSQL (or Postges) maintains a repository for Linux systems like Centos to install the database. This repository is known as pgdg and is maintained at yum.postgresql.org or yum.pgrpms.org

Installation of the Postgres comes with psql, this is a CLI to manage Postgres.

Installation of PostgreSQL 9.3 on Centos 6.4 is as follows;

Step 1:
Open a CLI as root user and retrieve the pgdg repo RPM, then install it. This will allow the Centos to find for software from the pgdg.

wget http://yum.pgrpms.org/9.3/redhat/rhel-6-x86_64/pgdg-centos93-9.3-1.noarch.rpm

rpm -ivh pgdg-centos93-9.3-1.noarch.rpm

Step 2:
Install the client and server.

yum install postgresql93 postgresql93-server




Step 3:
Initialise database and tables, and start. This creates the default user postgres.

service postgresql-9.3 initdb
service postgresql-9.3 start

You can now login with the default user to the Postgres terminal as follows;

su postgres
psql -dpostgres

Step 4:
As the postgres user, create an administrative user, then log out from the psql (use \q), then the shell (Control-d).

CREATE role dbmsuser LOGIN PASSWORD 'password' SUPERUSER;

Step 5:
Edit Postgres configuration file;

vi /var/lib/pgsql/9.3/data/postgresql.conf

Uncomment the line and save.
#listen_addresses = ‘localhost’ and change it to listen_addresses = ‘*’

vi /var/lib/pgsql/9.3/data/pg_hba.conf

Add a line at bottom of the file to allow non-local connections, e.g.
host    all             dbmsuser        10.0.0.1/32            md5


Post installation
chkconfig postgresql-9.3 on

Ref: 

Thursday, February 20, 2014

Italian God Fathers May Run Open Source

In the current economic challenges, many countries are looking at saving cost via ICT and Italy is not an exception. Umbria, a region in the centre of Italy that produces cheese, lentils, truffles and have a relatively large number of small industries. This 900,000 strong population region is home to an active GNU/Linux User Group Perugia.

In 2012, Umbria saw the start of a revolution to switch to LibreOffice, which is LGPL or open source software (OSS) licensed. LibreOffice provides office productivity tools that include a word processor (like MS Word), presentation (like MS Powerpoint), spreadsheet (like MS Excel) and more. Advantages of this software is that it is free to download and install for almost all computers as it supports MS Windows, Linux and Mac platforms. Most popular editable document formats can be open and edited and its interface is rather intuitive and easy to use. It comes with a portable version where users can install it on a USB drive and carry it around to run LibreOffice any where. A built in PDF converter allows any edited file to be frozen and to be distributed with read only access and consistent format.

MS Office have been introducing its OOXML format through the docx formats which will eventually required every organisation to purchase an upgrade license for MS Office and this will incur la high upgrade cost. LibreOffice by default save files in Open Document Format or ODF (International document standards ISO/IEC 26300:2006) and it also supports past versions of MS Word, Excel and Powerpoint.

Through LibreUmbria, schools were introduced to use LibreOffice as their primary document editing applications before it was expanded further further to other organisations. This also received the government's top innovation award for Italian Government Projects in 2012/2013. Will the rest of the Italian Government and private organisations follow suit?

Read up news on the region of Umbria to switch over from MS Office to LibreOffice.

Jan 16, 2014 from ZDNet
Sep 26, 2013 from LibreOffice
Jun 5, 2013 from Document Foundation Blog

List of open standards can be found at ISO Public site

Wednesday, February 5, 2014

Passwordless root SSH Public Key Authentication on CentOS 6

Need to remote login to linux servers?

Create a public key and store it in the remote server. By default it is recognised as authorized_keys but this is fully configurable. The ssh-keygen generated the public key with RSA that is by default called id_rsa.pub

A well written article to do this can be found at Passwordless root SSH Public Key Authentication on CentOS 6

An alternative sshpass command as mentioned in January 31, 2014 Linuxpromagazine seems to force users to make the password visible. Good that this is no available in a default Centos 6, as this will help to maintain good password practices. I.e. do not have password kept where anyone can read it.

Monday, January 20, 2014

Top 10 Database Engines based on appearance in Internet

Ever wonder how to justify choice of database engines? Some have opted on comparison of specifications and limitation of the system. Now through manual use of ahem.."big data" we can see a list of top 10 database engines.

 DB-ENGINES.COM

Among some of its criteria includes appearance in Google and Bing search engine. Frequency in technical discussion in Stack Overflow and DBA Stack Exchange. Then there are LinkedIn, Indeed and Simply Hired.

Information and table above above is from DB-Engines.com.


Monday, November 18, 2013

Backup Samsung S3 with KIES

Time to send the Samsung Galaxy S3 to the workshop as its difficult to charge despite changing several chargers. Problem: Need to wriggle the USB connection to charge.

Attempting to use KIES from Samsung.

A) Install KIES

Step 1. Download and install from http://www.samsung.com/my/support/model/GT-I9300RWDXME-downloads?downloadName=SW

Step 2. Update the KIES for PC (Final part of the installation above for 18 Nov 2013, version 2.6.1.13105_6_1 (See diagram below)


B) Run Backup
Step 1. Start Samsung KIES (not the LITE)

Step 2. Click the tab "Back up/Restore". Yes, they put a space between Back and up.


Step 3. Click "Select all items".

Step 4. Select which directory to store the backup. Click "Tools" ->Preferences ->Browse

Step 5. Click "Backup". Now they decided there is NO space between in this word.






Wednesday, October 16, 2013

Moodle support for Tin Can and SCORM 2004

If anyone have been said to implement SCORM 2004 engine, its never been highly compliant and Moodle is no exception. On Oct 2004, Moodle has officially abandoned further development of its SCORM 2004 engine. Details of its SCORM module can be found at
http://docs.moodle.org/24/en/SCORM_module

Surely lots of users will be in the lost or may drop SCORM development. Moodle News suggest the use of Tin Can SCORM for future development of learning objects. Moodle site suggest use of the SCORM cloud from Rustici Software where the SCORM Cloud plugin is free, but not the account.

The SCORM Cloud free trial account provides 100MB and 10 active registration (what does that mean?) at https://cloud.scorm.com/sc/user/PostSignUp

Following are helpful links to setup the SCORM Cloud

1. Getting the Moodle package
http://scorm.com/scorm-solved/scorm-cloud-features/app-integrations/moodle-integration/

2. Integrate with Moodle
http://support.scorm.com/entries/21366321-Installing-the-SCORM-Cloud-Moodle-Module

Wednesday, September 18, 2013

Manage log files from getting too big

Log files in Linux can be managed via the logrotate command (See man pages). If the log files start growing too big, it can be difficult to audit these log files.

Here is an example to create a new log file each week as the weekly cron (See man pages) service runs.

Following is an example where the cakephp application is installed. It will create a new file each week for 52 times before deleting the oldest file. Each file will be appended with a running number starting with "1". If the log file is missing, no errors will be printed/emailed and nothing will be done if the log file is empty.

Step 1: Create the configuration file

Create the file /etc/logrotate.d/cakephp with permission 644 (owned by root) and following contents;

/var/www/html/mymesyuarat/*/tmp/logs/*.log {
    weekly
    missingok
    rotate 52
    compress
    dateext
    delaycompress
    notifempty
    create 640 root root
    sharedscripts
}

Step 2: Ensure that the logrotate service is running.

The above configuration can be tested with the following command;

logrotate -s /tmp/logrotatestatus /etc/logrotate/cakephp