WHAT IS LINUX OPERATING SYSTEM

• Linux is a free and open source operating system
• Linux is always free for anyone to use, modify, and distribute
• Linux is copyLeft
• There are different organization are disturbuting there own Linux operating system in 32-bit, 64-bit and power pc

• A Linux distribution, often simply distribution or distro, is   a member of the Linux family of Unix-like computer operating systems.
• Distros mainly based on ‘Look and Feel’ and Applications.
• As for now we have more than 100+ linux os in the world wide.
• Some of famous Linux Distros are :

     Red Hat Fedora, Debain, SuSe,Ubuntu, Gentoo,Mint,Slax etc

• Linux Distribution also called as Linux Distro.
• There are many different versions of Linux, and unlike other commercial operating systems that are controlled, distributed and supported by only one company, the core of Linux is free to distribute and use. 
• We are all know about Linux OS is Open source and Free Use.It is used by programmers, organizations, profit and non-profit companies around the world in order to create Operating systems to suit their individual requirements.
• To prevent hacking attempts, many organizations keep their Linux operating systems private. Many others, make their variations of Linux available publicly so the whole world can benefit at large. These versions/ types /kinds of Linux operating system are called Distributions.

Distribution List Of Free OS

1. Linux Mint
2. Kali Linux
3. OpenSuse
4. Ubuntu
5. BOSS
6. Skole
7. Deepin
8. Linux Lite
9. Pentoo
10. Slackware
11. Mandriva
12. Debian
13. Gentoo
14. Fedora  ... upto 250+ distribution

WHAT IS LINUX OPERATING SYSTEM

Linux Process Management

• Linux is a multitasking system
• Multiple programs can be executed at the same time
• Ultimately, a program needs to be executed by a CPU
• If there is only one CPU, how multiple programs can be executed at the same time? By time sharing
• That is, all programs are claimed to be executing. In fact, most of them are waiting for the CPU
• A program that is claimed to be executing is called a process

For a multitasking system, a process has at least the following three states

Ready state

 – All processes that are ready to execute but without the CPU are at the ready state

 – If there is only 1 CPU in the system, all processes except one are at the ready state

Running state

 – The process that actually possesses the CPU is at the running state

 –If there is only 1 CPU in the system, at most there is only one process is at the running state

Sleeping state

 – The process that is waiting for other resources, e.g. I/O, is at the sleeping state

 - Processes will alternatively get into the CPU one after the other (called the round robin scheme)

 - process will be “in” a CPU for a very short time (quantum)

 - For Linux, each quantum is about 100msec

At the time that a process is selected to be “in” the CPU

 – It goes from ready state to running state

After that, it will be swapped out

 – It goes from running state back to ready state

Or it may due to the waiting of an I/O device, e.g. mouse

 – It goes from running state to sleeping state

When obtaining the required resource

 - It goes from sleeping state to ready state 

Linux Process Management

What is Apache Web Server

• Apache is generally used as the world's most popular Web server. Used for different web technologies like php. jsp, Flex etc etc...
•  Its mainly designed for Linux and Unix Environment.
• Apache web server can also use in Windows and Mac Environment also.

What is Apache Software Foundation

• Apache Software Foundation (ASF) is maintaining the updates . Its a non profit corporation.
• It is incorporated in Delaware, USA, in June of 1999. 
• he ASF is a natural outgrowth of The Apache Group, a group of individuals that was initially formed in 1995 to develop the Apache HTTP Server.
• The name 'Apache' was chosen from respect for the various Native American nations collectively referred to as Apache, well-known for their superior skills in warfare strategy and their inexhaustible endurance. It also makes a cute pun on "a patchy web server" -- a server made from a series of patches -- but this was not its origin. 
• The Apache Web server provides a full range of Web server features, including CGI, SSL, and virtual domains. Apache also supports plug-in modules for extensibility. 
• Apache is free software, distributed by the Apache Software Foundation that promotes various free and open source advanced Web technologies.

What is Apache Web Server

What is Open Source Software

OSS are computer programs in which the source code is made available to the general public for use and/or modification from its original design free of charge, i.e. open. Open source programs are typically created as a collaborative effort in which programmers offer the user a flexibility of use and share the changes within the community.

A certification standard is issued by the Open Source Initiative that indicates that the source code of a computer program is made available free of charge to the general publc. The rationale for this movement is that a larger group of programmers not concerned with proprietary ownership or financial gain will produce a more useful and bug free product for everyone to use. The concept relies on peer review to find and eliminate bugs in the program code, a process which commercially developed and packaged programmes do not utilize. Programmers on the Internet read, redistribute and modify the source code, forcing an expedient evolution of the product. The process of eliminating bugs and improving the software happens at a much quicker rate as the information is shared through the open source community

What is Open Source Software

Characteristics Of OSS

OSS has many characteristics the important ones are:

i) It is generally acquired freely
ii) Manufacturer or developer has no right to claim
royalties on the distribution or use
iii) Source code is accessible to the user and  distributed with the software
iv) No denial to an individual or to a group to access
source code of the software
v) It has provision of modifications and derivations
under the programme’s original name
vi) Rights of facilities attached to the programme must not depend on the programme’s being part of a particular software distribution
vii) Licensed software can not place restriction on other software that is distributed with it
viii) Distribution of License should not be specific to a
product and License should be technologyneutral,etc.

Characteristics Of OSS

What is Linux Distros

● A Linux distribution, often simply distribution or distro, is   a member of the Linux family of Unix-like computer operating systems.

● Distros mainly based on ‘Look and Feel’ and Applications.

● As for now we have more than 100+ linux os in the world wide.

● Some of famous Linux Distros are :

     Red Hat Fedora, Debain, SuSe,Ubuntu, Gentoo,Mint,Slax etc

What is Linux Distros

Why to Use Linux OS

•      Costs less

•      Stable

•      Reliable

•      Extremely powerful

•      Free Online Help

•      Security

•      Free From Virus

•      Free Software Available for All kind of stuff.

Why to Use Linux OS

What is Kernel

·        It is a Core or nucleus of an operating system

·        It Interacts with the hardware

·        First program to get loaded when the system starts and runs till the session gets terminated

·        Different from BIOS which is hardware dependent.

·        Kernel is software dependent

Kernel types

•         Monolithic

–       All OS related code are stuffed in a single module

–       Available as a single file

–       Advantage : Faster functioning

•         Micro

–       OS components are isolated and run in their own address space

–       Device drivers, programs and system services run outside kernel memory space

–       Supports modularity

–       Lesser in size

What is Kernel

What are the benefits of Linux

What are the benefits of Linux (or)

Advantages of Linux

Linux can give you:

•         A modern, very stable, multi-user, multitasking environment.

•         Advanced graphical user interface. Linux uses a standard, network-transparent X-windowing system with a "window manager" (typically KDE or GNOME but several are available).

•          The graphical desktop under Linux can be made to look like MS Windows (or probably ANY other graphical user interface of your choice).

•         Dozens of excellent, free, general-interest desktop applications. These include a range of web browsers, email programs, word processors, spreadsheets, bitmap and vector graphics editing programs, file managers, audio players, CD writers, some good games, typing tutor, etc.

•         Freedom from viruses. Linux has no viruses because it is too secure an operating system for the viruses to spread with any degree of efficiency.

•         Linux is quite positively here-to-stay because of its open-source nature (Linux cannot possibly be put out-of-business). It is a standard selected for countless projects that are not going to go away, and some of them are quite "mission-critical." Try the International Space Station, for which Linux is the operating system 

What are the benefits of Linux

What is MySQL

•  MySQL is a database server
•  MySQL is ideal for both small and large applications
•  MySQL supports standard SQL
•  MySQL compiles on a number of platforms
•  MySQL is free to download and use
•  MySQL is Open Source.
•  MySQL is maintaining by Oracle Company
•  MySQL is RDBMS
•  MySQL is a popular choice of database for use in web applications.
•  MySQL is the world’s most popular open source database.
• MySQL's ease of use

What is MySQL

3 C's of Open Source

3 C's of Open Source

Code

Some popular world-class open source projects are Linux, Apache, MySQL, PHP, and Ruby

Collaboration

 Collaborative tools are the backbone of the open source way. Tools include version control systems, IRC, mailing lists, wikis, blogs to help developers working on  building code together.

Community

Sharing ideas and developing code across the Internet with developers all over the globe forms the community for most open source projects.

3 C's of Open Source

How is Linux Used

Linux Os are used mainly for following purposes

1.        Personal Workstation
2.     Educational Purpose
3.     File and Print Server
4.        Internet Service Provider
5.       Three-tier Client/Server
6.     Turnkey System

How is Linux Used

Linux Certification Programs

What are the Linux Certification Programs are there

 Industry certification programs

–       Red Hat Certified Technician

–       Red Hat Certified Engineer

–       LPI Certification

–       Linux Certified Administrator (LCA) Certification

–       Linux+ Certification

–       Novell Certified Linux Engineer

Linux Certification Programs

Before Linux OS

–        In 80’s, Microsoft’s DOS was the dominated OS for PC

    – single-user, single-process system

–     Apple MAC is better, but expensive

–     UNIX is much better, but much much expensive. Only for                    minicomputer for commercial applications

–     People was looking for a UNIX based system, which is cheaper           and can run on PC

–     Both DOS, MAC and UNIX are proprietary, i.e., the source code of           their kernel is protected

–        No modification is possible without paying high license fees

Before Linux OS

Linux KDE in Tamil Language

●Latest release 2.2 contains Tamil language

●KDE is the first complete Tamil desktop environment

●Tamil is the first Indian language to appear in KDE

●Uses Unicode internally and TSCII fonts for display

●About 120 applications translated

●Major hurdles in translating applications into Tamil already crossed

●The effort established synergy between the translators and Tamil scholars

●With the release of version 2.2 in August, the Tamil desktop will be commercially available from major Linux vendors in the near future

Linux KDE in Tamil Language

What is GCC In Linux

GCC, an acronym for GNU Compiler Collection, is a compiler generation framework which generates production quality optimizing compilers from descriptions of target platforms. It follows an open development model whereby its source is available for all for inspection and modification. It supports a wide variety of source languages and target machines (including operating system specific variants) in a ready-to-deploy form. Besides, new machines can be added by describing instruction set architectures and some other information (eg. calling conventions).

Novices may want to see the  Wikipedia introduction to GCC. For experts, the GCC page contains a wealth of information including installation instructions, reference manuals (which include users' guides as well as details of GCC internals), a set of frequently asked questions, a wiki page for the developers of GCC, additional reading material, and several mailing lists for more detailed issues and queries. Anexcellent description of GCC internals can also be found on Wikipedia.

"When Richard Stallman announced the first public release of GCC in 1987, few could have imagined the broad impact that it has had. It has prototyped many language features that later were adopted as part of their respective standards — everything from "long long" type to transactional memory. It deployed an architecture-neutral automatic vectorization facility, OpenMP, and Polyhedral loop nest optimization. It has provided the toolchain infrastructure for the GNU/Linux ecosystem used everywhere from Google and Facebook to financial markets and stock exchanges. We salute and thank the hundreds of developers who have contributed over the years to make GCC one of the most long-lasting and successful free software projects in the history of this industry."

Source Fr5om IIT Bombay

What is GCC In Linux

FOSS Security Features

Open source software are very powerful and strong security. Thats why now a days Linux Os are used for Servers

Some of the common Features foss:

1. Iptables
2. ConnTrack
3. Anti-sniff
4. SniffIt
5. Roots
6. Security focus, instead of user-friendliness

Now a days Hacking attempts on servers are frequent, malware, trojans and viruses are commonplace and tools to help the hacker are readily available. No software is 100% immune from security vulnerabilities but the open source process itself delivers superior security performance

FOSS Security Features

About Open Source Licensing

·        Licensing is a key part of open source software.

·        There are many open source licenses.

·        Choosing the right license for software is important.

·        All open source licenses have to be submitted for approval by the Open Source Initiative (OSI).

·        The approved license list is at http://opensource.org /licenses/alphabetical

What is Open Source Software Licensing