Opensource

                                        What is Linux?

 History of UNIX :

• UNIX is an Operating System (OS).
• UNIX was developed about 40 years ago i.e., 1969 at AT&T Bell Labs by Ken Thompson
  and Dennis Ritche.
• It is a Command Line Interpreter.
• It was developed for the Mini-Computers as a time sharing system.
• UNIX was the predecessor of LINUX.

History of LINUX: 

• LINUX was created by Linus Torvalds in 1991. 
• LINUX is a open source.
•  LINUX is a variant of UNIX.

Why LINUX/UNIX?

• LINUX is free.
• Can view and edit the source code of OS
• It is fully customizable.
• 30Years to get the bugs
• Important in shared environments and critical applications
• LINUX has better security structure.
• High Portability
• Easy to port new H/W Platform
• Written in C which is highly portable

Kernel:

• Kernel is the heart of the operating system.
• It is the low level core of the System that is the interface between
  applications and H/W.
• Functions
• Manage Memory, I/O devices, allocates the time between user and
   process, inter process communication, sets process priority

 Shell:

• The shell is a program that sits on the as an interface between users and kernel
• It is a command interpreter and also has programming capability of its own.
• Shell Types
• Bourne Shell (sh) (First shell by Stephen Bourne)
• C Shell(sh)
• Korn Shell (ksh)
• Bourne Again Shell(bash)

File System:

• Linux treats everything as a file including hardware devices. Arranged as a
  directory hierarchy.
• The top level directory is known as “root (/)”.