Linux introduction, class 1

ACE Course CT01558
Linux Introduction
The Linux OS & OSS
2014Linux Introduction #1 1

 Purpose of an Operating System (OS)
 Key features of the Linux OS
 Origins of the Linux operating system
 Linux distributions and where to find them
 Common uses of Linux in the industry
Linux Introduction #1 2
Agenda
2014

Introduction to Linux
What Is Linux?
 Usually meant to refer to a UNIX-like operating system
 Free implementation of UNIX, cannot be called UNIX
 Implementation of the POSIX specification
 Linux Is Not UniX
Linux refers just to the kernel
 Much of the non-kernel software is GNU
 Other components come from many organizations, groups, &
individuals
2014

Linux Operating System
Linux
kernel
GNU tools,
compiler,
libraries
X graphics :
KDE GNOME
Other:
Apache, Database,
Multimedia
Linux
operating
system
2014

 An operating system (OS) is a collection of software
that manages computer hardware resources and
provides common services for computer programs
 Hardware: physical components inside a computer
 Software: set of instructions or programs that allow
hardware components to manipulate data
Operating Systems
http://en.wikipedia.org/wiki/Operating_system
2014

 Hardware components include:
 Processor (CPU)
 Physical memory (RAM)
 Hard disk drives
 Sound cards, microphones
 Video cards, webcams
 Circuit boards
 Sensors: GPS, gyroscope, magnetometer
Operating Systems (Hardware)
2014

 Software components include:
 Processor (CPU) instructions [math, multi]
 Memory Manager (real or virtual)
 Process Manager
 Scheduling Manager
 Hardware drivers [disk drives, video, sound, sensors]
 Security [user, access control, terminations]
Operating Systems (Software)
2014

 Features include:
 Real-time or Scheduling Manager
 Multi-user
 Multi-tasking
 Networking
 Distributed – supercomputers!
 Embedded http://www.raspberrypi.org/
 The Raspberry Pi is a credit-card sized computer
that plugs into your TV and a keyboard!
 http://www.ouya.tv/ Android gaming console
Operating Systems (Features)
2014

 Two different types of software:
 Applications: programs designed for a specific use
and with which a user interacts
 Command Line Interface or prompt (CLI)
 Graphical User Interface (GUI)
 Desktop tools [calculator, file manager, web browser]
 Operating system software:
 Device Drivers: interacts with hardware
 Abstraction Layer: interacts with user applications via
Application Programming Interface (API)
Operating Systems (Software)
2014

Linux OS Layers

 Graphical user interface (GUI):
 component of an OS that the user can interact with using
the keyboard or the mouse
 System services:
 applications that handle system-related tasks:
 Printing
 Scheduling programs
 Provide network access
Operating Systems (continued)
2014

Operating Systems (GUI)
A Linux graphical user interface
2014

 Name & History
 Creator
 Cost
 License
 Target system type
 http://en.wikipedia.org/wiki/Comparison_of_operating_systems
Operating Systems Comparison

 Linux OS
 Runs a variety of applications on a variety of different
hardware components
 Multiuser and Multitasking OS
 Has the ability to manage thousands of tasks at the
same time
 Allows multiple users to access the system
simultaneously
The Linux Operating System
2014

 Core component is called the Linux kernel
 Written almost entirely in the C programming language
 Software can be used to modify appearance of Linux,
but the kernel is common to all Linux
 Important to understand Linux kernel version
numbers to decide which version is appropriate for
user needs: x86 or 64
Versions of the
Linux Operating System
2014
https://www.kernel.org/

The GNU System
 The GNU system comes from the
Free Software Foundation: FSF.ORG
 Founded by Richard M. Stallman in the 1980s
 Objectives were to create freely distributable UNIX tools
 Software should be free from patents & commercial ownership
 GNU provides many UNIX commands & useful applications
 Linux and GNU were an ideal match in the early 1990s
 Linux kernel needed supporting software
 GNU needed a kernel (it now has the Hurd)
2014

 Open Source Software (OSS):
 Programs distributed and licensed so that the source
code is available, free of charge, to anyone who wants
to examine, utilize, or improve upon it
 Mayor repository sources:
 http://www.gnu.org/
 http://sourceforge.net/
 http://www.fsf.org/
 https://github.com/plans
Licensing Linux
2014

 Implications of OSS:
 Developed very rapidly through widespread
collaboration
 Bugs (errors) are noted and promptly fixed
 Features evolve quickly based on users’ needs
 Perceived value of the software increases because it is
based on usefulness, not on price
Licensing Linux (continued)
2014

Licensing Linux (continued)
2014
http://en.wikipedia.org/wiki/Software_licenses

 GNU Public License (GPL):
 Stipulates that the source code of any software
published under its license must be freely available
 Users who modify the source code must also
redistribute the modified code freely
 Artistic license: OSS license allowing source code to
be distributed freely, changed only at discretion of
original author
Types of Open Source Licenses
2014

 Most closed source software is sold commercially
 Usually bears label of manufacturer, such as Microsoft
or Electronic Arts software
 Freeware: distributed free of charge; source code
usually not available
 Shareware: initially free, but requires payment after a
period of time or for use of certain features
Types of Closed Source Licenses
2014

 Common software available for Linux includes:
 Scientific and engineering software
 Software emulators
 Web servers, Web browsers, and e-commerce suites
 Desktop productivity software
 Graphics manipulation software
 Database software
 Security software
Linux Advantages:
Meeting Business Needs
2014

 Customers using a closed source OS must rely on the
OS vendor to fix any bugs
 Waiting for a hot fix may take weeks or months
 Bugs and security loopholes in OSS programs can be
identified and fixed quickly
 Code is freely available and scrutinized by many
developers
Linux Advantages:
Stability and Security
2014

Linux Advantages: Flexibility for
Different Hardware Platforms
Partial list of hardware platforms on which Linux can run:
– Intel x86, IA-64 – M68K
– MIPS – PA-RISC
– Mainframe (S/390) – SPARC
– ARM, Atom – Ultra-SPARC
– Alpha
– PowerPC: Nintendo,
PS3, Xbox 360
http://en.wikipedia.org/wiki/List_of_Linux_supported_architectures

 Ability to control the inner workings of the OS
 To use Linux as an Internet Web server, compile the
kernel to include only the support needed to be an
Internet Web server
 Results in a much smaller and faster kernel
 Can choose to install only software packages needed to
perform required tasks
 Can use shell and PERL scripts to customize or automate
tasks
Linux Advantages:
Ease of Customization
2014

 Linux documentation can be found on the Internet
 Frequently asked questions (FAQs)
 HOWTO documents
 Linux newsgroups
 Linux User Group (LUG): Open forum of Linux users
who discuss and assist each other in using and
modifying the Linux OS
Linux Advantages:
Ease of Obtaining Support
2014

Linux Advantages:
Cost Reduction
Calculating the Total Cost of Ownership
2014

The History of Linux
Timeline of UNIX and Linux development
2014

 Evolved from Multiplexed Information and
Computing Service (MULTICS)
 The first true multitasking, multiuser OS
 Written in the C programming language
 Portable OS
 OS from which Linux originated
UNIX
2014

 Berkeley Software Distribution (BSD)
 Version of the original UNIX source code
 Common flavors of UNIX today include:
 Sun Microsystems’s Solaris UNIX
 Hewlett-Packard’s HP-UX
 IBM’s AIX UNIX
UNIX (continued)
2014

 First developed by Linus Torvalds in 1991
 Published under the GNU license
 Linux kernel developed collaboratively and centrally
managed
 Hackers developed Linux add-on packages and
distributions
 Linux is simply a by-product of OSS development
Linux
2014

Linux Distributions
http://distrowatch.com/
2014

Linux Distributions
Kernel
GNU
X
Other
Linux
Operating
System
Red
Hat
Mint
Ubuntu
Others
+
+
+
+
Installation tools,
configuration tools,
SUPPORT, etc.
2014

What Is a Linux Distribution?
 A Linux distribution is:
 A preconfigured kernel
 GNU utilities
 X graphical environment (KDE, GNOME)
 Other generic software components (Apache)
 Distributor-specific installation & configuration
 Support
2014

X
 A powerful networked graphical environment
 Developed at MIT, freely distributable
 X.org - complete implementation of X based on the X11R6 standard
 Servers typically do not require graphics
 Some useful system administration tools are graphical
 X graphical tools can be run on a server and displayed remotely
MIT = Massachusetts Institute of Technology
2014

Other Linux Applications
 UNIX software packages have been ported
 UNIX packages are often distributed in source form
 Korn Shell, emacs, zip, chkconfig
 Many server components are generic UNIX software
 Apache, sendmail, BIND, Samba
 Some software components are
 Free implementations of commercial applications
 OpenSSH, OpenMotif, GNUPG
 Internationalization
 Multiple languages
 Unicode support!
2014

 May be customized to provide services for a variety of
companies in a variety of situations
 Workstation services: services used on a local computer
 Server services: services made available for other
computers across a network
 Mobile devices: tablets and cell phones!
 Game Consoles
Common Uses of Linux
2014

What Could Your Net Look Like?
VPN link to remote site
Linux
Web server
Linux
router
Linux mail server
for POP/IMAP
clients
Linux print server
for UNIX clients
Linux DHCP
server
Linux
FTP server
Linux
NFS file server
NIS server
DNS server
Linux
firewall
Linux
VPN gateway
Linux
SMTP server
Linux file and
print server for
Windows clients
To the
Internet
2014

 Linux is well-suited for centrally sharing resources
 More economical to share files and printers over a network
 Inherently fast and light
 A distribution specific to a certain task can be installed on the
central server
 Can share resources with a computer running another OS
File and Print Servers
2014

Navigating Filesystem
 Using Nautilus (Gnome
graphical filesystem
browser)
 Click on “Computer”
icon or
 “Applications”,
“System Tools”, “File
Browser”
2014

 Application server: intermediary between a client
computer and a database
 Database: organized collection of data that is arranged
into tables of related information
 Database Management Systems (DBMS): set of programs
designed to allow for creation, modification, manipulation,
maintenance, and access of information from databases
 Application servers can provide management functionality
Application Servers
2014

 Clustering: combining several smaller computers to
act as one large supercomputer
 Beowulf clustering: most common Linux method of
clustering
 Scalability: the ability for a computer to increase
workload as the number of processors increases
 Clustering computers often results in better scalability
than adding processors to a single computer
Supercomputers
2014

 Scientific and engineering community often needs
customized programs (NASA, NOA)
 OSS programs can be used or modified
 OSS software available for physics, astrophysics,
biophysics, biocomputation, data mining, and many
other scientific and engineering fields
Scientific/Engineering Workstation
2014

 Workstation software designed for end users in office
and home environments
 OSS packages available for:
 Graphics editing software
 Desktop publishing software
 Media software
 Financial software
 Office productivity suites
 Bittorrent clients
Office/Personal Workstation
2014

 Purpose of an Operating System (OS)
 Key features of the Linux OS
 Origins of the Linux operating system
 Linux distributions and where to find them
 Common uses of Linux in the industry
Summary
2014

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Linux introduction, class 1

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Linux introduction, class 1