MODULE 4
Jan 03, 2016
MODULE 4
“Hello everbody out there using minix – I am doing a (free) operating system just a hobby, won’t be big and professional like gnu) for 386(486) AT clones”
What is Linux?
In 1991, Linus Torvals – 21 years old student.
University of Helsinki, Finland. Developing Linux Kernel as a hobby. He wishes to improve upon the design
of Minix, an educational operating system.
Minix source code serves as the starting point for Torvalds’s Linux project.
In Sept 1991, 1st version of Linux Operating System release
What is Linux?
Linux is a most popular, free open-source operating system.
Free distributed, full featured OS. Available to the public for
examination and modification. Developed based on Unix
What is Linux?
Linux was originally created by Linus Torvalds with the assistance of developers from around the globe.
Linux is free to download and install, edit and distribute.
Linux is a very powerful operating system
Popular throughout the world.
What is Linux?
User of the OS benefits from a community of developers actively debugging & improving the kernel.
Absent of licensing fees and restrictions – ability to completely customize the OS to meet specific needs.
Linux is not centrally produced by a corporation, Linux users can receive technical support for fee from Linux vendors or for free though a community of users.
What is Linux?
Runs on multiple hardware platforms From the smallest to the largest, and
serves a wide variety of needs from servers to movie-making to running businesses to user desktops.
Because of its speed, stability and low cost, Linux became the fastest growing operating system for servers (the computers than run big companies, the Internet, large networks, etc.).
What is Linux?
For all the same reasons Linux has become so popular on servers, to desktop computers.
There are versions of Linux (called distributions) created specifically for desktop use, such as Linspire and Freespire, which give you the stability of Linux, but with the ease of a Windows environment.
Linux Distributions
also known as the GNU/Linux distribution
a family member of the Unix-like software distributions
Linux kernel lies as the basis of these distributions.
Linux distributions are available in different forms because most of the kernels and supporting packages used are combination of open source and free software.
Linux Distribution
This is the reason why they are widely used in embedded systems and for things like booting from a floppy disk
Linux Distribution
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
List of Linux Distribution 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.
List of Linux Distribution 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.
Linux 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
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
GNU and 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
Linux OS
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
Linux OS
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
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
Linux Commands - 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
Linux Command - cp
The cp program copies files and directories. Examples:
cp file1 file2 –copy a single file cp file1 file2 file3 directory –copy
multiple files to a different directory
Linux Command - 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: mv file1 file2–rename a file mv file1 file2 file3 directory–move
files to a different directory
Linux Command - chmod
The chmod Command We use the chmod command to
change the access mode of a file. This command comes in many flavors, but we'll be talking primarily about one of them.
chmod who=permissions filename This gives “who” the specified permissions for a given filename.
Linux Commands
rm The rmcommand deletes (removes) files.
Example: rm filename
rmdir The rmdircommand deletes directories. Example: rmdir directory name
mkdir The mkdircommand is used to create directories.
Example: mkdir directory name
Linux Commands
man Online help for each of the various Linux
commands Linux will display any information you type Example: 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
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
Linux System Administrator 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
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
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 addusercommand, which does that for you
Basic Linux Administration – Linux User 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
Basic Linux Administration – Linux User 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
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
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
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
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
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
OpenOffice –Sun Microsystems office suite http://www.openoffice.org
Samba –Windows connectivity client and server http://www.samba.org
Apache Web Server –the standard on the Internet http://www.apache.org
PHP scripting language –create dynamic web pages http://www.php.net
GIMP –powerful image program comparable to Photoshop http://www.gimp.org
MySQL Database –free, powerful, easy to use http://www.mysql.com