Module 4 INTRODUCTION TO LINUX OPERATING SYSTEMS

Chapter Overview CMPF112: Computing Skills2 Introduction and History of Linux Linux Systems and Distributions Manipulating Linux GUI Linux Command-line Interface Overview of Linux Software and Tools Basic Linux Administration

Introduction and History of Linux

What is Linux? An operating system Free, open source, software A community CMPF112: Computing Skills4

Introduction Unix was developed in the mid-1970s when minicomputers and mainframe were popular The problem with Unix is its inaccessibility by programmers and developers The earlier commercial versions of Unix were costly, sometimes costing more than a pc hardware Linux began by Linus Torvalds at the University of Helsinki, Finland Linux today was developed with assistance of programmers worldwide CMPF112: Computing Skills5

History Developed as project of Linus Torvalds, student at University of Helsinki Based on Minix, small Unix OS First release in 1991 with version 0.02 Version 1.0 was released in 1994 Current stable version is CMPF112: Computing Skills6

History Richard StallmanLinus Torvalds

Linux Systems and Distributions

Linux OS Distributions Many different distributions Private: –Usually specialized Firewall Minimal install Floppy disk Linux Language specific CMPF112: Computing Skills9

Linux OS Distributions (cont.) Linus Torvalds created Linux and distributed early versions across the Internet for the enjoyment of many hardcore hackers Today, Linux is distributed in many ways, including CD-ROMs, tapes, Internet and even inside diskettes A Linux distribution has the utilities and other programs in Unix CMPF112: Computing Skills10

Linux OS Distributions (cont.) Linux is constantly evolving and hardware support is frequently updated Not many hardware are compatible with Linux But the compatibility of hardware has improved since Linux gain more popularity nowadays CMPF112: Computing Skills11

Linux OS Distributions (cont.) Corporate: –Continually improving installs –Larger device and standard support –Large amount of packages (programs) – usually 3-4 CDs worth Big names: Red Hat, Mandrake, SuSE CMPF112: Computing Skills12

List of Linux Distributions There are a number of Linux distributions across the world A few most popular distributions: –RedHat – The most popular Linux. Evolving fast with great GUI’s and other auto-detect facilities and tools. Latest version : RedHat 9.0 –Slackware – The first Linux distribution created. Inherited from the real Linux from Linus Torvalds. Quite tedious to master but good for research purposes.urce software –Mandrake – Competitors to RedHat. Has good GUI’s and good for servers. Easy to master and has many online help. –Lindows – It has most Linux and Windows capabilities. Evolving fast to compete Microsoft Windows. The good news is : it is FREE –UnitedLinux – A combination of Slackware, SuSE and Caldera. Competitor for RedHat and big threat for Windows. –Other distributions such as : SuSE, Caldera, Debian, OpenLinux, FreeBSD, etc. CMPF112: Computing Skills13

The OS “Linux” refers to the kernel, the core of the OS The kernel is what actually makes the computer run Developed under the GNU General Public License CMPF112: Computing Skills14

GNU General Public License Sponsored by the Free Software Foundation A method for a program author to provide the code yet protect it from becoming proprietary Any program developed under this license can be changed at will However, no money can be charged for the code itself, it must be freely available Can charge for support, development and distribution costs CMPF112: Computing Skills15

GNU & Linux Tools GNU stands for “GNU’s Not Unix” Richard Stallman created the foundation to help write free versions of the Unix software tools Linux benefits from most of these tools, which is why often you’ll see GNU/Linux CMPF112: Computing Skills16

Overview of Linux Features

Linux OS: Details Multitasking OS –Every application has their own memory space –The kernel keeps track of everything Multiuser –One computer can serve the needs of many users at once –Each user can have different settings for the same application –Standard Unix/Linux concept CMPF112: Computing Skills18

Networking Unix built the Internet All networking protocols are supported (IPv4, IPv6, Wireless, NFS, SMB…) Web servers, file servers, firewalls, NAT machines to name a few CMPF112: Computing Skills19

Some Added Features Programmable shells –Linux is the most flexible OS available where programmers can write their own programs inside Linux shells Device independence under Linux –Linux is device independence as well as Unix –Programmers all around the world developed drivers of many hardware for Linux CMPF112: Computing Skills20

Windows Interface Since no one company controls everything, there are numerous desktop environments Each is just as interface to the X window system tools The two most popular are KDE and GNOME Most window managers have features like multiple desktops per user CMPF112: Computing Skills21

CMPF112: Computing Skills22 Windows Interface (cont.) KDE

Windows Interface (cont.) CMPF112: Computing Skills23 GNOME in Red Hat 9

Linux Command-line Interface

Linux Command Lines ls The ls command is used to list the contents of a directory. It is probably the most commonly used Linux command. It can be used in a number of different ways. Here are some examples: –ls – list the files in the working directory –ls /bin – list the files in the /bin directory (or any other directory you want to specify) –ls –l – list the files in the working directory in long format –ls –l /etc /bin – list the files in the /bin directory and the /etc directory in long format –ls –la – list all files (even ones with names beginning with a period character, which are normally hidden) in the parent of the working directory in long format CMPF112: Computing Skills25

ls command

Linux Command Lines (cont.) cp The cp program copies files and directories. Examples: me]$ cp file1 file2 – copy a single file me]$ cp file1 file2 file3 directory – copy multiple files to a different directory CMPF112: Computing Skills27

Linux Command Lines (cont.) mv The mv command performs two different functions depending on how it is used. It will either move one or more files to a different directory, or it will rename a file or directory. Examples: me]$ mv file1 file2 – rename a file me]$ mv file1 file2 file3 directory – move files to a different directory CMPF112: Computing Skills28

Linux Command Lines (cont.) rm The rm command deletes (removes) files. Example: me]$ rm file rmdir The rmdir command deletes directories. Example: me]$ rmdir directory mkdir The mkdir command is used to create directories. Example: me]$ mkdir directory CMPF112: Computing Skills29

Linux Command Lines (cont.) man Online help for each of the various Linux commands Linux will display any information you type Example: me]$ man ls – it will show description of ls command more Display a screenful of a text file You can look through a text file without invoking an editor, printing the file, or trying to pause the terminal as it displays the file CMPF112: Computing Skills30

Linux System Administrator Every aspect of the system can fall within the realm of a system administrator Entire books have been written about just the software side, and for most system administrators, hardware, networks, and even programming fall into their laps Almost every user, and many administrators, never see what is happening as the system is booting CMPF112: Computing Skills31

Linux System Administrator (cont.) Those who do, often are not sure what is happening. From the time you flip the power switch to the time you get that first login prompt, dozens of things must happen, many of which happen long before the system knows that it’s running Linux Knowing what is happening as the system boots and in what order it is happening is very useful when your system does not start the way it should CMPF112: Computing Skills32

Overview of Linux Software and Tools

The Boot Process The process of turning on your computer and having it jump through hoops to bring up the OS is called booting, which derives from the term bootstrapping The process a computer goes through is similar among different computer types, whether it is a PC, Mac, or SPARC Workstation CMPF112: Computing Skills34

LILO – The Linux Loader This is basically a set of instructions to tell the OS how to boot That includes what OS to boot and from what partition, as well as a number of different options If LILO is installed in your master boot record, it can be used to boot basically any OS that you can install on that hardware Actually, most of the work was done by the boot loaders of the respective OS, but LILO was used to load start the boot process CMPF112: Computing Skills35

User Accounts Users gain access to the system only after the system administrator has created user accounts for them These accounts are more than just a user name and password; they also define the environment the user works under, including the level of access he/she has CMPF112: Computing Skills36

User Accounts (cont.) Users are added to Linux systems in one or two ways. –You could create the necessary entries in the appropriate file, create the directories, and copy the start-up files manually –Or, you could use the adduser command, which does that for you CMPF112: Computing Skills37

adduser command Adduser command useradd [-c comment] [-d home_dir] – [-e expire_date] [-f inactive_time] [-g initial_group] [-G group[,...]] [-m [-k skeleton_dir] | -M] [-n] [-o] [-p passwd] [-r] [-s shell] [-u uid] login

Linux Community Linux is by its nature a community The OS and applications only move forward by the help of many Help is a “HOW-TO” or a mailing list away Google.groups are an excellent source of information Linux Documentation Project is a huge resource of “HOW-TO” documents – written by the community CMPF112: Computing Skills39

Linux Software Thousands of programs already run on Linux Office suites, games, web development tools are probably the most lacking, although more are always developed StarOffice/OpenOffice is now available and very versatile CMPF112: Computing Skills40

Basic Linux Administration

Linux Users Root –Controls all system files –Only user that can do “anything”, even look at/delete another users’ files –Usually the only user that can install most programs Normal users –Each has a “home” directory –Files are separated from other users –Cannot edit system data/configuration –Often can’t even see system data CMPF112: Computing Skills42

Basic File Structure Hard disk is divided into partitions –Usually a minimum of 2: / (root) and /home –Idea is to keep user data and system data separated to prevent problems Users: 2 minimum –Super user (root) –At least one “regular” user CMPF112: Computing Skills43

Source Distribution Installation Requires source files, easily downloadable Knowledge of command line interface Installation of basic compiler 95% of all programs are compiled with GNU C++ compiler, freely available Understanding of the file system, where to place files File/Directory Permissions CMPF112: Computing Skills44

File Permissions Every file and directory has three sets of permissions –Read (r) – can read the file –Write (w) – can write, change and delete the file –Execute (x) – an executable script/file Permissions can then be set for three different groups –User – the person that owns (created) the file –Group – the group the user belongs to –Others – everyone else CMPF112: Computing Skills45

File Permissions (cont.) CMPF112: Computing Skills46

Useful Programs OpenOffice – Sun Microsystems office suite – Samba – Windows connectivity client and server – Apache Web Server – the standard on the Internet – CMPF112: Computing Skills47

Useful Programs (cont.) PHP scripting language – create dynamic web pages – GIMP – powerful image program comparable to Photoshop – MySQL Database – free, powerful, easy to use – CMPF112: Computing Skills48