OS Simulator

JavaScript Emulator For Linux:-

If you don't have Pc and you want to test any command or any application then you can use Online Linux Java emulator.
To use Java emulator click on below link

http://bellard.org/jslinux/ 

Windows Vista/7 Simulator:-
Some programmers created simulator to help learners to learn. I am giving below the links of all simulator. 
To use simulator click on below links.
All below links are simulator links. you can try all of them and select any one for longer use that you feel best for yourself.

http://www.vistasimulator.com/vista.php# 

http://www.ineedoshelp.com/win7/sim/desktop.html

http://www.temulator.com/

What is Linux

Linux is a high performance , yet completely free, UNIX-like operating system . In fact  It  is a kernel not an OS when it work along with other application/GNU Utilities then it is known as Operating system. Linux Distribution is a virus free and it does not require higher hardware configuration .

Kernel+Application Software = Linux based OS/Distribution
or
Kernel + GNU Utilities = A Complete Linux Based O.S.

Kernel & Kernel Feature

what is Kernel
Kernel is the main core of any Linux Based distribution. All linux based distribution is created on the basis of Linux Kernel.
Kernel is developed by Linus Benedict Torvalds in 1991. The first kernel version was 0.01 that was developed in 1991. In 1994 Linus Torvalds created kernel 1.0 .
World first Linux based distribution is created by RED HAT company in 1994 on the base of Linux Kernel 1.0 .
Features of Kernel:-
    1. Memory management

    2. Hardware and Software interaction

    3. Giving Output of any command

    4. Error Management.    

History Of Linux

In 1969, Four programmer Ken Thompson, Dennis Ritchie, Rudd Canady & Doug McElroy made a program in Bell labs( AT & T ) which does not have any name in year 1969.
Brian Kernighan checked that program & found it is very good software for client & networking purpose.
He gave the name Unix to this program on 1st January 1970 (epoch time).
First Operating System that time that program was written in Assembly language.
In 1972, a programmer Dennis Ritchie started converting this program in C language. (Also called founder of C language).
In 1973 UNIX was launched in C language
1980‐ Berkeley Software Development (a part of research program of Berkeley University) Launches open BSD (a small program written in a single floppy).
In 1981‐ Launched MS‐DOS 1.0
In 1984‐ UNIX open source In 1985‐ First Graphical Based OS‐ Win 2.0.
In 1991, a student at university of Helsinki in finland named Linus Torvalds  who had been using minix, a non free unix like system, began writing his own kernel. He started by developing device drivers and hard drive access, and by September had a basic design that he called version 0.01 kernel. which is called Linux, was afterwards combined with GNU system to produce a complete free operating system.
In 1994‐ Red Hat Company (collection of Linux Sets) came into existence 96.8 % servers of Linux till 2009.

DEVELOPER OF LINUX KERNEL (LINUS BENEDICT TORVALDS)

Linux Distributions

There are many distribution of Linux. The reason of increasing Linux distribution regularly is that Linux is Open Source .User select Linux distribution as per their requirement.If you want to use Linux temporary purpose then you can go through Live CD.                            
 Popular Linux Distributions
RED HAT   FEDORA     UBUNTU   SUSE   MENDRIVA SLACKWARE   XENTOO   DISTRO WATCH   DEBIAN    FREE BSD   BACKTRACK    CENTOS  BOSS     MEPIS

Linux vs windows

1. File/Directory permission (Action: Read/Write/Execute, permissions can be given on behalf of the particular User/group/Others).

2.All the unix configuration as files rather than Registry (windows).

3.Linux is Open Source while Windows is Bound Source.

4. In Linux their are Lots Of Distribution while Windows have limited distribution.

5.In Linux you need to enter password during installation while If you are installing windows you can left password blank.

6.Linux is More Secure incompare of windows. Linux has inbuilt feature of Iptables and Selinux to improve security. Iptables allow and prohibit Ip traffic based on port no , Ip address , Domain name etc. On the other hand Selinux provide file level security

7.You can play around the Linux through LIVE CD'S on a Windows machine.

8.By default LINUX have multiuser, multitasking, multiprocessing, multiprogramming features. Perhaps this will not be available on windows except some versions , In that case you need to PAY & BUY the extra features in windows.
9. 60% web Servers are running in Linux while only 40% web servers are in windows this fact is admitted by Microsoft CEO steve Ballmer.
Beneficial feature of Linux 

• Security
• Open Source
• Free Distributions
• Virus free
• with the help of wine software we can run .exe files
• In Linux everything is considered as a file so easy to take backup and resolve problems

WHY LEARN/USE LINUX

1. Linux is more secure in compare of windows.
2. Linux is Opensource while windows is BoundSource.Linux cost nothing but if you want to use Windows in Enterprise level you need to purchase that OS.
3. More than 200 Distributions are available in Linux.
4. Every Company uses Linux in their company server for security purpose.
5. Linux is Virus free while windows get infected by virus.
6. Being Unique is great joy. As everyone knows that Windows is very easy to use while Linux is little tough than Windows.
Suppose you have a LAPTOP and you want that no one of your family members/friend use your LAPTOP then Simply install Linux based os. You know the Linux while your friend dont know linux so only you will be able to Use your Computer.

Which company use Linux

Each MNC company use Linux in their process for their work . Company uses Linux in their Server because:
*** LINUX distribution is free of cast
*** VIRUS Free
*** Require Low Hadware Configuratiion.
*** In Linux everything is considered as a file so if any problem will be occur in any Server then Server Admin need to simply replace the file from Back-up Server.
*** Linux never hang . As everyone knows that if u will start multiple task then windows  hang easily but Linux never hang .


1. Google     2. IBM     3. Panasonic     4. Cisco     5. Amazon.com     6. Wikipedia     7. New York Stock Exchange     8.NASA     9. Jet Airways    10. LIC    11.Bank Of Brazil (90,000 Linux Desktop)     12.HCL    13. US Department of defense 14. US Navy     15. French parliament 16. DELL

RHEL5 vs RHEL6

REDHAT Enterprise Linux server (RHEL) is an Opensource. It is popularly used as Server Operating system.

RHEL6 have a lot of features:-

The advantages are

***  RHEL6 introduces the use of KVM (Kernel-based Virtual Machine) as its hypervisor. In the earlier releases Xen hypervisor was used. The main advantage of KVM is that a new kernel should not be installed like in Xen. It also supports the installation of many virtual operating systems like Windows, Linux, Solaris,etc. It is easy to manage.

***  Ext4 is made the default filesystem. Ext4 has many new advantages than Ext3 which is used in earlier versions of RHEL. Ext4 is comparatively faster and easy to manage. It supports supports up to 100TB with the addition of Scalable Filesystem Add-one.

*** Improved level of Security RHEL6 has advanced level of security. SELinux (Security Enhanced Linux) features are improved and a new set of SELinux rules has been added to provide security to virtual machines from hackers and attackers. This new feature is called SVirt.

*** New Networking Features RHEL6 is released with improved and new networking features. It supportsIPv6. It uses NFSv4 (Network File Transfer) for the sharing of files in the network rather than NFSv3. It also supports iSCSI (internet Small Computer System Interface) partitions. The network manager in RHEL6 supports Wi-Capabilities.

*** Use of Drivers RHEL6 has drivers for speeding up operations under KVM, VMware and Xen.

*** Increase in the support period provided by Red Hat. RHEL6 has a long period of support provided by Redhat. It provides updates for 7 years and also a extra 3 years of service as paid service. Therefore it means that its period of support is twice the period of support provided by other linux distributors like Ubuntu , Suse , Mendriva , Debian, etc.

*** Improvements of minor updates

Red Hat releases minor versions such as 6.1, 6.2. These minor versions are the accumulated updates of the major version. The new minor releases will not only contain bug fixes but will also have major changes and new features.