A simple presentation to understand what Linux is

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2.  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
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3.  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
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4.  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
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5.  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
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6.  Linux is not an Operating System
 Linux is a kernel
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➲ Linux Distrobutions use the Linux kernel
together with the GNU Operating System
➲ A kernel is a program that allocates and controls
hardware resources in a system

7.  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
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8.  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
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9.  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
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10.  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
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11.  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
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12.  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
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13.  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
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14.  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
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15.  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/
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16.  IBM AIX
 Sun Solaris
 SGI IRIX
 HP HP--UX
 Compaq TRU64 UNIX
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17.  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
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18.  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
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19.  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
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20.  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
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21.  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
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22.  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
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23.  Level 0
 Halt
 Level 1
 Single User mode
 Level 2
 Reserved
 Level 3
 Full Mulituser
 Level 4
 Reserved
 Level 5
 Xwindows
 Level 6
 Reboot
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24.  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
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25.  Redhat
 Mandrake
 Suse
 Lycoris
 Gentoo
 Knoppix
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26.  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
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27.  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
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28.  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
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29.  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
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30.  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
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