Introducting Linux

Chapter 1:
Introducing Linux
The Complete Guide To Linux System
Administration

The Complete Guide to Linux System Administration 2
Objectives
• Describe how Linux was created and how it
compares to other operating systems
• List versions of Linux currently available
• Outline the skills required and challenges facing
a system administrator
• Log in and begin using a Linux system

Objectives (continued)
• Explore a Linux file system from the command
line
• Locate additional information about commands
you want to use or learn about

A Brief History
• Popular graphical computers
– Apple Macintosh
– Microsoft Windows
• Linux
– Alternative for people whose computing needs
require something different

Understanding Operating Systems
• Software
– Collection of instructions that control the tasks a
computer performs
– Can be changed without disassembling the
computer and rewiring
• Operating system
– Software that helps other programs control
computer hardware and interact with users

Understanding Operating
Systems (continued)
• Application
– Software program that provides service for
computer user
– Cannot act without “permission” from
operating system

Operating System Functions
• Initialize computer hardware
• Allocate system resources to programs
• Keep track of multiple programs running at same
time
• Provide organized method for all programs to
use system devices

Operating System Functions
(continued)
• Major operating system components:
– Kernel
– Device drivers
– Shell
– Utility programs
– Graphical user interface (GUI)

The UNIX Operating System
• UNIX
– Operating system
– Originally created at AT&T Bell Labs in
early 1970s
– Designed to control networked computers that
were shared by many users
– Features and low cost of Linux effectively driving
UNIX out of market

The Free Software Foundation
and the GNU Project
• Free software foundation (FSF)
– Software itself should not be restricted in
distribution by standard commercial license
agreement
• GNU project
– Completely free version of UNIX
– Written from scratch

The Free Software Foundation and
the GNU Project (continued)
• Software license
– Legal definition of who can use software and how
it can be used
• GNU general public license (GPL)
– Very different from standard commercial software
license
– Author agrees to give away source code
– Anyone is licensed to redistribute it in any form

The Free Software Foundation and
the GNU Project (continued)
• GNU GPL
– Any modifications to the source code must be
licensed under the GPL
– Sometimes called copyleft
– OpenSource
• Refers to software licensed under GPL
• Public domain
– No one has copyright to software
– Not same as GPL

Linux Arrives
• Linus Torvalds
– Decided to create UNIX-like operating system
kernel for IBM-compatible PC
– Solicited help via Internet
– Released Linux kernel under GPL
• Linux development method
– Person identifies need and begins writing program
– Developer announces project on Internet

Linux Arrives (continued)
• Linux development method (continued)
– Others respond and work on different parts of
project
– Person leading project releases software
– People download source code and try program;
send back information about problems
– Developers fix bugs
• Forking
– Creating new project based on existing source
code

Motivating Free Software
Developers
• Why would so many people devote so much
effort to something without expecting any
reward?
– Fills developer’s specific technical need
– Respect of like-minded professionals
– Sense of contribution and community
– Valuable boost to developer’s resume

The Strengths Of Linux
• Stability
• Security
• Speed
• Cost
• Multiprocessing and other high-end features
• Applications

Linux In The Market
• Linux is packaged and sold
• Red hat software
– Current market leader

Linux Distributions
• Linux distribution
– Productized version of Linux
• Includes operating system kernel along with other
components
• System utilities
– Related to managing Linux system
• Price
– Generally between $2 and $100

Linux Distributions (continued)

Red Hat Software
• Fedora distribution
– Free product
• Red Hat Enterprise Linux configurations
– WS (workstation)
– ES (enterprise server)
– AS (application server)
• Red Hat Enterprise Linux
– Sold as subscription service

Red Hat Software (continued)
• Red Hat Enterprise Linux
– Updates from Red Hat Network (RHN)
• Red Hat
– Excels in service and support offered to large
companies using Linux

Hardware Requirements
• Can run on very minimal hardware
• Recommend that computer have minimum of:
– 1 GB of free disk space
– 64 MB of RAM
• For Red Hat Enterprise Linux installations:
– 256 MB of RAM
– 300 MHZ CPU
– 800 MB of free disk space

Version Numbering
• Version numbers assigned to:
– Each release of Linux kernel
– Each component of Linux distribution
– Linux distributions
• Most users select latest available version

Version Numbering (continued)
• Kernel version number components
– Major version number
– Minor version number
• Even indicates production release
• Odd indicates development release
– Patch-level number

Linux Certification
• Industry certification programs
– Red Hat Certified Technician
– Red Hat Certified Engineer
– LPI Certification
– Linux Certified Administrator (LCA) Certification
– Linux+ Certification
– Novell Certified Linux Engineer

Linux Certification (continued)
• Red Hat’s certification program
– Very highly regarded
– Training program consists of three courses

The Work of a System
Administrator
• Linux is increasingly part of information
technology infrastructure of large organizations
• Knowledge of Linux can set you on path to a
fulfilling and profitable career

Careers in Linux
• System administrator
• Network administrator
• Software engineer
• Trainer
• Technical writer
• Product marketing
• Business consultant

The Duties of a System
Administrator
• Role
– Make technology work and continue to work for
those who do “real work” of organization
– Enable others to use technology benefits
• Responsibilities
– Create new user accounts
– Maintain system hardware
– Train end users

The Duties of a System
Administrator (continued)
• Responsibilities
– Keep system running smoothly
– Document system
– Define procedures and policies
– Recover from emergencies
– Plan systems

Ethics, Privacy, and the Law
• Working as system administrator involves many
ethical issues
• Fellow employees count on your work to do
theirs
• Best route to success comes through making
employer successful
• System administrators guild (SAGE)
– www.sage.org

Starting To Use Linux
• Should have access to computer with Linux
installed

Logging In
• Log in
– Identify yourself to operating system so that it
knows:
• You are authorized to use system
• Which parts of system to permit you to access
• User account
– Set of permissions to use system
– Has associated user name and password

Logging In (continued)
• Modes
– Graphical
– Text

Graphical Environments
• Popular desktops
– KDE desktop
– GNOME desktop
• Features
– Taskbar
– Main menu
– Desktop icons
– Multiple overlapping windows

Opening a Terminal Window
• Terminal window
– Resembles console
– Enter commands from keyboard

Exploring the File System

File System Concepts
• Files are organized into directories
• Names are case sensitive
• Names can be long
• Names may contain many different types of
characters
• Can include file extensions
– Not required

File System Concepts (continued)
• Directory relationships
– Parent directory
– Subdirectory
• Path
– List of directories
– Absolute path
– Relative path
• Linux does not have separate drives

File System Concepts (continued)
• Root directory
– Parent of all directories
– /
• /Usr subdirectory
– Contains the greatest number of files and
subdirectories on newly installed systems

Managing Files With
Graphical Utilities
• File manager
– Displays contents of a directory as collection of
icons or file names
– Manage files and directories
– Choose Browse Filesystem on main menu
• Home directory
– Subdirectory where all personal files are stored

Working at a Command Line
• Linux system administrators should be very
comfortable working at command line
– Much faster way to perform most tasks
– Some tasks cannot be use graphical interface
• Commands
– pwd − mv − slocate
– cd − ls − file
– mkdir − cat − cp
– rmdir − touch

(continued)
• Command-line prompt consists of:
– User name
– Name of computer at which you are working
– Last directory name in current working directory
– $ character

(continued)
• Parameters
– Define what command will operate on
• Options
– Alter how command operates
• Timestamp
– Information about date and time when event
occurred

Finding Command Help
• Learn more details
• Explore additional Linux topics

Reading Linux Documentation
• Linux documentation project (LDP)
– HOWTOS
• Linux on the internet
– www.google.com
• Documentation included with software packages
– Software packages provide some documentation
– /Usr/doc
– /Usr/share/doc

Linux Command Information
• Man pages
– Online manual pages
– Man command
• Info page
– Definitive source of information
– Info command

Summary
• Operating system
– Provides interface between computer hardware
and applications run by user
• Linux offers important features, such as:
– Stability
– Speed
– Security
– Flexibility
– Low cost

Summary (continued)
• Several Linux certification programs are available
• Several versions of Red Hat Enterprise Linux
• Most users rely on GUI to log in and use Linux
– Text-only mode also available
• Information in Linux is stored in directories
– Begins with root directory /

Summary (continued)
• Linux files can include file extensions
– Few Linux programs rely on file extensions to
define what file contains
• Information about Linux is available online
– Part of LDP

Introducting Linux

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