I ntroduction to Linux

1. Introduction to Linux

2. Introduction to Linux • What is Linux, and Who Created it? • GNU and the GPL • Unix/GNU, What is the Difference? • POSIX Compliance • Other POSIX Operating Systems • Uses of Linux • Advantages and Disadvantages

3. What is Linux • Linux is a UNIX clone • It can run on 32 bit and 64 bit hardware • Linux is a true multitasking environment • Fully capable of taking advantage of multiple processors • Can address up to 64 GB of RAM • Partial POSIX Compliance

4. Penguin Power • Linux is free • Anyone can download and compile the source • The code can be modified by anyone provided the modifications are released to the community

5. History • The history of Linux began with Unix in 1969 • Unix was created at Bell Labs with the goals: • Simplicity • Recycleable code • Written in C as opposed to assembly • Development started in 1991 • Linus Torvalds wanted to create a free implementation of UNIX • By 1993 there were 12000 Linux users • Today Linux rivals UNIX in stability and scalability

6. The Kernel • Linux is not an Operating System • Linux is a kernel • A kernel is a program that allocates and controls hardware resources in a system • Linux Distrobutions use the Linux kernel together with the GNU Operating System

7. The Linux Kernel • The Linux kernel is currently maintained by Linus Torvalds and a few hundred other developers • Releases are numbered in a very ordered fashion. • Major.minor.patchlevel • Odd minor numbers are development kernels • Thus • 2.4.20 latest stable kernel • 2.5.67 latest development kernel • Will become the 2.6 kernel

8. Design • The Linux kernel has a monolithic design • The other approach is the microkernel design • Both have their upsides and downsides • Monolithic kernels • Easier to build and design • Generally faster • More recompiles • Less object oriented • Micro kernels • Considered safer • Easier to develop drivers for • Only recompile for upgrades • Generally slower • Much harder to build and design

9. Other *NIX Kernels • The BSD kernel • This is the kernel used by the open source BSD's • FreeBSD, OpenBSD, NetBSD • It is neither GNU nor GPL • The GNU HURD • Hird of Unix Replacing Daemons • Hurd of Interfaces Representing Death • The world's first doubly recursive acronym • Micro kernel • Not very functional

10. Isn't a GNU an Animal? • GNU stands for GNU Not Unix • The goal of GNU • Create a free and complete UNIX-like operating system • This has been in development since 1984 • Towards this goal the GNU project has released: • GCC, GNU Emacs, Bash, to name a few • For more information see the GNU Manifesto • http://www.gnu.org/gnu/manifesto.html

11. What is the GNU GPL? • The GNU General Public License • Ensures that GNU software stays free • This is done through Copy Lefting • Any modification to GPL software is required to be released to the public • Linux is released under the GPL • Due to its restrictive nature the GPL has recently come under fire • http://www.linux.org.uk/GPL.html

12. Does the GPL Matter? • Depends on your point of view • Not as important for users • Very important for developers • Any GPL code that is incorportated into a program makes the entire program GPL • No closed source software can use any GPL software

13. So Unix Costs Money and GNU/Linux is Free • Essentially this is the case • Both have the goals of POSIX compliance • Commercial UNIXes are in general closer • This is generally in implementation, not in use • Commercial UNIXes generally perform better in large systems • But even this is difference is shrinking • The biggest difference is that UNIX is trademarked and must be commericial—not free

14. POSIX? Another Operating System? • Nope, its yet another acronym • Portable Operating System Interface • POSIX is a set of specifications • Describes how the operating system should behave • Both to the user, and to other programs • POSIX was created to combat the plethora of UNIXes that popped up in the 1980, all of which had a different look and feel

15. POSIX cont... • The Open Group controls the UNIX trademark • They also release their own UNIX specification • The latest POSIX specification has been merged with the Open Group's UNIX specification • For more information see: • http://www.pasc.org • http://www.opengroup.org/

16. Other POSIX OSes • IBM AIX • Sun Solaris • SGI IRIX • HP HP--UX • Compaq TRU64 UNIX

17. So Why Should I Use Linux? • As a server platform • few other operating systems can match Linux in: • Performance • Price • Stability • For Developers • Resources: • Linux has a tremendous number of tools available for developers. And they are all free. • For the Desktop • It's fun

18. Advantages • Linux is free • Can't say that enough • It's great for poor college students • Learning Linux means learning UNIX, and UNIX is the largest server platform in the world • Community • The Linux community is very active and helpful • This makes support very rapid

19. But it's hard to learn • Linux is much harder than Windows • It's harder to use than Windows • It lacks all those great automated installation tools • You have to manually configure hardware • There is lots of hardware out there that just won't run in Linux

20. So You Are Ready to Take the Plunge • What do I need to know? • Not all distros are the same • Linux From Scratch is a bad starting place • Internet Resources • www.linux.org • www.tldp.org • www.justlinux.org • www.desktoplinux.org • What distro should I start with? • Redhat • Mandrake • Suse

21. Some Linux Basics • File System • Linux is much more hierarcal than Windows • Everything starts at the root • / • Boot -- contains the kernel and system map • Bin -- contains the basic system binaries • Dev -- all the device entries • Etc -- can't think of any other place to put it • Home -- where all the users live • Lib -- system libraries • Mnt -- place to mount filesystems • Proc -- system information • Root -- the root user's home • Sbin -- system binaries • Usr -- where user accessible programs go • Var -- logs and such

22. Basics cont... • CLI • The command line interface • Bash is the most common shell • The CLI in Linux is quite useable • Navigation • ls -- lists files and directories • cd -- changes directories • rm -- removes files • Navigation switches • Most programs have options that you can pass to them via switches, for ex. ls -h gives you all the options that ls can take and what they do

23. 6 Runlevels • Level 0 • Halt • Level 1 • Single User mode • Level 2 • Reserved • Level 3 • Full Mulituser • Level 4 • Reserved • Level 5 • Xwindows • Level 6 • Reboot

24. XWindows • Linux Graphical Environment • Invoked via the startx command • Two major environments • KDE • Gnome • The difference is primarily in philosophy • Redhat trys to erase the differences with Bluecurve • Does everything Windows does and more

25. A Few Good Distros • Redhat • Mandrake • Suse • Lycoris • Gentoo • Knoppix

26. Hat's off • Redhat • Pros • Easy install • Tons of graphical tools • Great hardware support • One of the most mature distros • Cons • It's slow • Their stock kernel is somewhat bloated • Installs files in non-standard directories • Not customizeable

27. Drako • Mandrake • Based on Redhat • Modified to suit desktop systems more than Redhat • Supports that funky DVD Decoder Card you have to use • More on the edge than Redhat • Uses a modified kernel

28. Tame the Lizard • Suse • Pros • Avoids much of the bloat of Redhat and Mandrake • Great hardware support • The easiest Linux installation I have ever had • Cons • Still hard to customize

29. Perfection • Gentoo • Pros • Builds Linux from scratch, optimizing for the architecture of your PC • Blazing speed • Highly customizeable • User Forums are a great place for support • Runs Quake and Unreal Tournament 2003 out of the box • Has a kernel specifically modified for gamers • Cons • Can be overwhelming • Takes a long time to build • Do not trip over the power cable while it is building

30. Knoppix • Self contained • Can boot almost any pc that supports cdrom booting • Settings can be stored locally or on USB pen drive • Great to learn on • Does not require resizing partions or wiping drives