The Complete Guide To Linux System Administration
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
• 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
• 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 • 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 • 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 • 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 development method – 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
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 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
• 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 • 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 • 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 • 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
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 • Directory relationships – Parent directory – Subdirectory
• Path – List of directories – Absolute path – Relative path • Linux does not have separate drives • 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 – Nautilus – 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 • Command-line prompt consists of: – User name – Name of computer at which you are working – Last directory name in current working directory – $ character
• 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
• 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 /
• 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