1. Chapter 1: Welcome to Linux An intro to UNIX-related operating systems

2. In this chapter … History of Unix GNU-Linux Why Linux?

3. Long ago, in a galaxy far away … Computing power was costly –UNIVAC cost $1 million CPU time was a premium –Most mainframes had less computing power than a calculator on the shelf at Wal-Mart Jobs were submitted into a queue –Only one process at a time – scheduling nightmare

4. What was needed Allow multiple users to access the same data and resources simultaneously Service many users more cheaply than buying each their own machine The ability to run multiple processes at once And do so while maintaining user segregation and data integrity

5. Enter Unix, pride of Bell Labs Originally written in PDP-7 assembly language by Ken Thompson To make it work on multiple architectures (portable), Thompson rewrote Unix in B Dennis Ritchie developed C, and with Thompson, rewrote Unix in C

6. What was so great about it? Multiuser Multiprocess Non-proprietary Economical for business Initially given for free to colleges and universities (great tactic!)

7. Descendents and bastards … Started at Bell Labs Picked up and continued by AT&T (SVR4) UC Berkeley derives BSD Sun Solaris IRIX Minix, XINU Linux

8. What happened? UNIX became commercialized Proprietary code, specialized distributions Costs started to become a hindrance So … let’s make our own Unix …

9. GNU Richard Stallman decides that there should be a free version of Unix available Forms the GNU project – GNU’s Not Unix Writes all of the system programs and utilities to mimic Unix variants Everything but a kernel (Hurd)

10. Final piece Universities trying to teach Unix and OS design can’t afford Unix Andrew Tanenbaum writes Minix Linus Torvalds, dissatisfied with Minix, writes his own – Linux

11. GNU-Linux Torvalds has a perfectly functioning kernel – but no system programs Finds a perfect candidate in GNU Together, the operating system world was changed dramatically

12. Free you say? GNU-Linux is free … Free as in speech, not free as in beer Free to view, copy, modify, and release Profit still to be had from packaging, support, and additional original code

13. Why Linux? Software Hardware Portability Standards $$$

14. Software An almost limitless library of programs Applications, services, utilities Many free, some commercial Source code often available along with pre- built binaries

15. Hardware Supports thousands of peripherals and pieces of hardware Multi-platform: x86, PPC, Alpha, SPARC, MIPS, 64-bit, SMP (multiproc systems) Emulation of hardware for testing and development

16. Portability Entire operating system written in C Shared system libraries available for all supported architectures Code written on one platform can be compiled on any system with minimal, if any, tweaks

17. Standards Much of GNU-Linux already meets POSIX (Portable Operating System Interface for Computer Environments) and Unix System V Interface Definition (SVID) Standardized for commercial and government use

18. And don’t forget … It’s free! (or at least really cheap!) That’s why Linux is often the operating system of choice to teach OS design and Unix courses We’ll be using RedHat Enterprise Linux 4 – not free but a fraction of the cost of Unix

19. Features Overview Multiuser Multiprocess / Multitasking Hierarchical Filesystem BASH Shell command line interface / programming language Many useful utilities built-in Rich networking support