Antivirus

There is no need of antivirus software in Linux. I am using Linux from past 3 years and I didn't find a single virus but if you want to install antivirus, then there is a lots of AV for linux like AVG, Avast and many more. Linux is fast and most secure OS.

How to update ubuntu

Open up terminal and write down the following commands
1.sudo apt-get update
It will check for packages whose updates are available
2. sudo apt-get upgrade
It will install the updates.

How to install software in ubuntu

Installing softwares in ubuntu is very easy

1. Open the software center and find the software from a stack of software's and hit the install
button. Your software is installed.
2. If you wann do it in hard way open a terminal and write the following command(cmd) in terminal
sudo apt-get install chrome (for ubuntu)
yum install chrome (for rhce and fedora)
3. You can also install software from synaptic package manager in Ubuntu.
4. you can install software from http://www.getdeb.net/ for debian based linux
In all of the above method you need a working internet connection.

There is also other way to install software

You can download software from internet if it is a .deb (for debian based) or .rpm(for reh hat based) package then you can install them by double clicking on them.

If this is a zip file or tar file then extract them and their is a file in it readme read that file follow the instructions. ther are simple three steps

1. ./configure

2. make

3. make install

and your software is installed.

Linux Commands

Next cmd is sudo cmd

sudo cmd means "take actions as superuser".

When you type sudo before a cmd it will provide you the super user (root) powers.

eg open terminal type 

sudo shutdown -h now after hitting enter it will ask for password enter the password of root user and your system will shutdown. 

History

Linux is a Unix based operating system. Linux is developed by Linus Torvalds and first version of Linux kernel is released on 5th oct 1991.

Linux was originally developed for Intel x86-based personal computers but now it has been ported to more computer hardware platforms than any other operating system. Linux is used on desktops, server,  and in supercomputers. 10 fastest supercomputer runs on some variant of Linux. Linux also runs on embedded systems such as mobile phones, tablet computers, network routers, televisions and video game consoles. The Android system in wide use on mobile devices is built on the Linux kernel.

Linux is a free and open source software. Free means you have not to pay for this Operating system like window. Open source means you are free to used, modified, and distributed source code, commercially or non-commercially by anyone under licenses such as the GNU General Public License.

Linux come with a lot variety of desktop environments:-

1. Gnome

2. kde

3. gnome-shell

4. unity

5.xfce and many more

Linux Commands

The first command(cmd) that is most important is man command. man cmd is an interface to the on-line reference manuals.
Terminal is like command prompt in window. Terminal provides a command line interface.
Open a terminal and write  man with the topic name or cmd name eg. man fprintf, man man

It will provide every information about that topic.

Attention

Most of the people thinks that Linux is most difficult Operating system to use. I want to say that it is only in your mind just give it a try and you will forget Window for ever. Ubuntu is the most user friendly Linux based Operating system.