Introduction to Linux OS

Linux Operating System

In 1969, Thompson and Ritchie designed and built an OS having an elegant file system, a command interpreter (called shell), and a set of utilities.  In 1973, they rewrote the entire system in C - a high level programming language that was invented by Ritchie himself.

 

The University of California, Berkley (UCB) created a UNIX of its own and was named BSD UNIX (Berkley Software Distribution  UNIX).  These versions became popular worldwide, especially in universities and engineering circles.

 

Sun used the BSD system as a foundation for developing their own brand of UNIX and named it SunOS.  Today, their version of UNIX is known as Sun Solaris.  Similarly, there are other flavors of UNIX developed over a period of time: IBM's AIX, HP-UX, DEC's Digital UNIX and Tru64 UNIX.  Then the Linux wave arrived and most of these vendors are offering Linux too.  Today, most supercomputers run UNIX, and handheld devices are using Linux.

Linux - A Successor of Unix:

Linux was developed having UNIX as a reference model. Therefore, the basic architecture and features of Linux and UNIX are the same. In fact, Linux is also considered as another version of UNIX. The main difference between Linux and UNIX is that Linux is free and open source.  However, various distributors of Linux can charge a price for Linux. In addition, Linux doesn’t involve any licensing issues. 

 

Linux is licensed under the GNU General Public License. This licensing policy states that a person can make any number of copies of software and distribute it freely, or charge a price for it. We can also download Linux free of cost from the Internet. 

Linux and GNU

Although, UNIX finally turned commercial, Richard Stallman and Linux Torvalds (father of Linux) wanted to develop and distribute a free version of UNIX.  Stallman is the founder of Free Software Foundation, formerly known as GNU - a recursive acronym for "GNU's Not Unix."  Many of the important Linux tools were written and supported free by GNU. 

Linux is distributed under the GNU General Public License, which makes it mandatory for developers and sellers to make the source code public.  The most popular GNU/Linux flavors are: RedHat, Caldera, SuSE, Debian and Mandrake.  Linux is particularly strong in networking and cost-effective in setting up an Internet Server or a local internet.

Linux has development tools, such as C, C++, FORTRAN, Pascal and scripting languages such as awk, Perl and Python.  Many of these scripting languages are free of cost.  Moreover, Web Servers (such as Apache) and Web Browsers (such as Netscape) provide their versions that are compatible with Linux, free of cost.

Linux - An Open Source OS:

Linux was developed as a cooperative effort over the Internet, so no company or institution controls Linux. Software developed for Linux reflects this background. Development often takes place when Linux users decide to work on a project together. When completed, the software is posted at an Internet site, and any Linux user can then access the site and download the software.

The potential for Linux-based software is explosive. Linux software development  always takes place in an Internet environment and it is global in scope, enlisting programmers from around the world. The only thing we need to start a Linux-based software project is a web site.

Most Linux software is developed as open source software. This means that the source code for an application is freely distributed along with the application. Programmers over the internet can make their worn contributions to a software’s development, modifying and correcting the source code.