Creating users and groups in Linux

Note: To try out the examples in this document, you would need root access.

To create a new user you use the adduser command. To add a user by called linuxjunky:

$ adduser linuxjunky

If you get a command not found error

$ /usr/sbin/adduser linuxjunky

To assign a password to your new user

$  passwd linuxuser

To grant ownership of a file to the new user

$ chown linuxjunky filename

To change grant ownership of a directory to the new user


Cascading Style Sheets (CSS) is a design language for styling HTML documents. In modern websites, HTML controls the structure while CSS controls its presentation. Let's suppose that you have some HTML formatting in numerous pages across your website. Would you want to manually modify 10,000 HTML elements to implement the new formatting? Ideally, there should be one place where you can make a change that modifies that formatting everywhere you need in the website. Technical term for this concept is "modular design". This technology already exists and it is called CSS.


If you had to work with IBM products, you probably have had to work with DB2. This page will get you up and running with DB2 in 10 minutes.

Delete (Drop) MySQL database

It is very easy to drop a MySQL database:

drop database database_name

Tons of blogs and articles online mention this command. Recently, however, I came across a database name which had spaces in them. For example:

company balances
electronics inventory
store employees

If I do:

drop database company balances

MySQL would complain that the databases company and balances do not exists. Naturally, the first thought on my mind was to enclose them the database.


The web is the most popular feature of the Internet and HTML is the backbone of the web. Everything that we see on the web is used with HTML. All fancy web technologies either generate or manipulate HTML in different ways.

Jar, War, and Ear files

.ear, .war, and .jar files are simply files zipped using Java jar tool. Each file is created for a different purpose:

.jar files

Jar (Java Archive) files contain libraries, resources and accessory files such as property files.

.war files

War (Web Archive) files contain web applications that can be deployed on any servlet/jsp container. It also contains other files required by the web application such as html, javascript, css, etc.

.ear files

Ear (Enterprise Archive) files contain EJB modules.

Java break and continue

Java’s break and continue statements are used to alter the flow of control.

break The break statement can be used in for, while or do-while loops. It is also used in switch structure. A break statement exits the loop without executing the rest of the code in the loop. In other words, if the program encounters a break inside a for loop, it exits the loop without executing the remaining statements even if the test condition of the loop is still valid.

Linux vs Linux Distributions

What is the difference between Linux and Linux distribution?

Linux is the core of the operating system i.e. the kernel. Kernel manages the physical resources of the computer and performs tasks such as starting and stopping programs, allocating memory, managing the processor, and managing network connections.

MySQL Alter Table

Alter table command is used for altering tables, table fields and table indexes

To rename a table:

ALTER TABLE mytable RENAME yourtable;

To add a column:


The first example create a column in the first position. The second command creates a column after the column id. The last example creates a column in the last position.


Node is an open source runtime environment for server-side applications. It allows you to run JavaScript on the server in addition to the browser. Almost all of the new and most widely used JavaScript solutions use Node in one form or another.

Installing Node.js

Download from Install with default options. To check, type the following on the terminal

PMP notes

Project Management Knowledge Areas Project management knowledge areas describe key project management competencies. There are four core knowledge areas, four facilitating knowledge areas and integration management.


PostgreSQL also called Postgres is an object-relational database management system that focuses on extensibility and standards-compliance.

Installing PostgreSQL

This quick walk-through are my notes for installing the PostgreSQL database server and the PgAdmin administration application on Ubuntu Linux, and also set up the server so it allows access to other PC's on your network.

Right for the basic installation, at the command-line, enter the following commands (or search for the listed packages in synaptic if you prefer that way of working):


Why learn python? Because it packs a powerful punch. Python is is easy to learn, user-friendly, highly extensible and overall a very powerful language. Like Java, it is fully object-oriented and it is as fast as C++. It allows scripting. I find that development in Python is more rapid than C++ or Java.

Python is free and fully supported by Linux, Windows and MacOS. There is strong community support and there are thousands of packages to extend the language.

Who is using python? Google. Need I say more?

Getting Started

To install on Linux:


Subversion (SVN) is a very popular open source versioning system. It manages files, directories, and changes made to files and directories over time by single of multiple users. If you have the time to thoroughly learn SVN, the only book you should read is available online for free. It can be found at However, if all you want to do is get started with SVN within an hour, you have come to the right place.

Ubuntu: could not reliably determine the server’s fully qualified domain name, using for ServerName

Error: Could not reliably determine the server’s fully qualified domain name, using for ServerName

Solution: 1. Open httpd.conf for editing

sudo vi /etc/apache2/httpd.conf

You might be surprised to see that the file is empty

  1. type the following:

    ServerName localhost

  2. Save file and restart apache server

    service apache2 restart