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Chapter - 1 Intoduction

History about Unix and Linux -

This chapter covers the History about Unix , Linux and What exactly SHELL is and what it does for us ..!!!!!! Until Unix and Windows came to industry , Operating system were designed keeping in mind for a particulary machine and hardware. Which were written in a Assembly language ( which is lowlevel language) and unreadble for human . These system were restricted for the hardware they are using for . The dependency was so much that program written for one system won't run on other hardware .later on Ken Thompson and Dennis Ritchie ,of AT &T fame, authored the Unix System.Thompson and Ritchie design and built a small system using a file system , a command line interpreter ( THE SHELL). The plan was to design an operating system which can run on more than one hardware . In 1973 , the operating system was re-written by them in High level language - C which was invented by Dennis Ritchie . Now one of the most strong feature of Unix system is portability.

Unix Second Birth -

U.S. government prevented AT & T from selling the computer Software. The company had no option but to sell the system to Educational and Research institute and they actually sold it with nominal fees but without any support .University of Califonia , Berkley (UCB), created a UNIX which is known as BSD UNIX ( Berkeley Software Distribution). The version of this UNIX became quite popular in universities and engineering colleges . Later , UCB gave up all development work on Unix . Berkley has filled the gaps left behind by AT & T , and later they have re-write the whole operating system in the way they wanted .They have created standard Unix editor vi and popular C shell. later on they have added improved file system feature , standard network distribution a networking protocol software (TCP / IP) that made internet possible .

Some Other flavours of Unix -

Slowly the Unix system became popular in Education and some business unit , Engineers started taking intrest in the UNIX and they have launched commercial relleases of UNIX . Sun Uses the BSD based system as a foundation for thier system and developed their own brand which is known as SUN Solaris . Others too have their own brands like IBM had AIX, HP had HP-UX . Today most of the supercomputers are using UNIX system. Later on the wave of Linux has came which is free and more suitable for the small to large applications.

As each vendor started enhancing the UNIX to create its own version orignal UNIX lost his idetntity .The BSD systems were much different than AT & T system . Later on , AT & T sold its UNIX business to Novell, who later turned over the UNIX trademark to a standards body called X/OPEN , now merged with the Open Group

The UNIX trademark is owned by The Open Group

Birth of Internet -

While the vendors were busy in enhancing their UNIX products , U.S. Defense department DARPA , a wing of this department has engaged some vendors to develope a reliable communication system using computer technology . The brilliant work was done by Vinton Cerf and Robert kahn , they made DARPA's ARPANET network using packet-switch technology to send the data . That has given the birth to TCP/IP - a set of protocol use by internet for communication.

DARPA commissioned UCB to implement TCP/IP on BSD UNIX . ARPANET converted to TCP/IP in 1983 , and in the same year , Berkeley released the first version of UNIX which had TCP/IP built in . The incorporation of TCP/IP into UNIX and its use as the basis of developement were two key factors in the rapid growth of the Internet (and UNIX).

Linux and GNU -

We know that UNIX was finally made commercial , but Richard Stallman and LInus Torvald has different plan . Torvald developed or we can say is the father of Linux, which is nothing but free UNIX system . Stallman runs the Free Software Foundation ( Formerly known as GNU - a recursive acronym stands for "GNU's" Not Unix !) Linux is distributed under GNU General Public Licence which makes it mandtory for developers and sellers to make the source code Public. Linux is particularly strong in networking , internet features and extremly cost effective .The most popular GNU/Linux flavors include RedHat,Caldera,SuSE,Debian and Mandrake.They support Internet servers, multimedia software like java, C,C++ compilers , interpreters like perl , python etc. Browsers like Netscape . Almost all major vendors committed to support Linux and many of them have ported their software to this platform .

Getting Started

- So far we have seen the history of UNIX and different UNIX and Linux Flavours . As we all know UNIX and LINUX systems are strong in their commands and they are very well known as Command base system . rather than discussing , lets run few commands and try to see the usage of these commands . we will see the command structure and detail features about these commands in our next chapter .

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