- OS can be defined as an organized collection of software consisting of procedures for operating a computer.
- OS provides an environment for execution of programs.
- OS acts as an interface between the user and the hardware of the computer system.
Operating system continues interacts with user in two ways.
- Operating system commands
- Enables user to interact directly with the O.S
- Operating System calls
- Provides an interface to a running program and the operating system . system calls in UNIX are written in ‘C’.
History of UNIX
- Ken Thompson at AT & T Bell laboratories designed UNIX in late 1960’s.
- Two versions of UNIX that emerged are AT & T UNIX and BSD Unix.
- In 1989, AT & T and sun Micro Systems joined together and developed system V release 4(SVR 4)
- Two of main standards mainly in use are POSIX and X/open standard. In 1988, MIT formed X consortium developed vendor _ natural X window system.
What is LINUX ?
- An open source UNIX like operating system.
- Initially created by LINUX Torvalds for pc Architecture ports exit for alpha and space processors
- Developer community world – wide contribute to its enhancement and growth.
Features of UNIX
- Multi – User , Multi tasking, time sharing
- File structure
- Strong network Supporting & advanced graphics