"I M LINUX"(Introductory module on Linux)

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WHAT IS LINUX

Linux an open source operating system. Its source code can be used freely, freely modified, and redistributed, both commercially and non-commercially, by anyone under licenses such as the GNU General Public License

HISTORYEVENTS LEADING TO CREATION

HISTORY- EVENTS LEADING TO CREATION

The Unix operating system was conceived and implemented by Ken Thompson and Dennis Ritchie (both of AT&T Bell Laboratories) in 1969 and first released in 1970. Its availability and portability caused it to be widely adopted, copied and modified by academic institutions and businesses. But it was not freely distributed.

In 1983, Richard Stallman started the GNU project. His idea was that unlike other products, software should be free from restrictions against copying or modification in order to make better and efficient computer programs. With his famous 1983 manifesto that declared the beginnings of the GNU project

HISTORY- CONT’D

HISTORY- CONT’D

MINIX, a Unix-like system intended for academic use, was released by Andrew S. Tanenbaum in 1987. MINIX was free and designed for education in computer science. Students of Computer Science all over the world read the codes to understand the very system that runs their computer.

THE CREATION OF LINUXIn 1991 while attending the University of Helsinki, Torvalds, curious about the operating systems and frustrated by the licensing of MINIX limiting it to educational use only (which prevented any commercial use), began to work on his own operating system which eventually became the Linux kernel. In order to make the Linux available for commercial use, Torvalds initiated a switch from his original license (which prohibited commercial redistribution) to the GNU GPL.

FEATURES OF LINUX

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Here are some basic and major features of Linux.

Free and Open source code for all: All source code of Linux is available, including the whole kernel and all drivers, the development tools and all user programs; also, all of it is freely distributable. Plenty of commercial programs are being provided for Linux without source, but everything that has been free, including the entire base operating system, is still free.

Multiuser: Several users can logon to the same machine at the same time There is no need to have separate user licenses.

Multitask: Several programs can run at the same time.

Multiplatform: runs on many different CPUs, not just Intel.

Networking: Linux supports networking and many network protocols like TCP, IPv4, IPv6, etc.

FEATURES OF LINUX

WHY LINUX IS BETTERForget about virusesLinux hardly has any viruses. A Linux virus is not impossible to get. However, Linux makes it very hard for this to happen, for several reasons:

Most people use Microsoft Windows, and pirates want to do as much damage (or control) as possible: therefore, they target Windows.

More eyes make fewer security flaws. Linux is Open source software, which means that any programmer in the world can have a look at the code (the "recipe" of any program), and help out, or just tell other developers

Is your system unstable?Have you ever lost your precious work because Windows crashed? Do you always shut down your computer the proper way, or do you sometimes just switch it off because Windows has gone crazy and doesn't let you do anything anymore? Have you ever gotten the "blue screen of death" or error messages telling you that the computer needs to be shut down for obscure reasons?

When a system crashes, it needs to be shut down or restarted. Therefore, if your computer can stay up and running for a long time, no matter how much you use it, then you can say the system is stable. Well, Linux can run for years without needing to be restarted (most internet servers run Linux, and they usually never restart). Of course, with heavy updates, it still needs to be restarted (the proper way). But if you install Linux, and then use your system as much as you want, leaving your computer on all the time, you can go on like that for years without having any trouble.

Don't pay for your operating systemUnless you obtained Windows illegally, you probably paid for it. Linux completely free of charge. Of course, some companies are making good business by selling support, documentation, hotline, etc., for their own version of Linux, and this is certainly a good thing. But most of the time, you won't need to pay a cent.

Need new software? Don't bother searching the web, Linux gets it for you.If you want to check out a new piece of software in Windows, you'll need to: Search the web to find which piece of software suits your needs. Find a web site that allows you to download it. Maybe pay for it. Actually download the software. Install it. Sometimes reboot your computer.

That's a lot of work to just try out something new.

With Linux, everything is much simpler. Linux has what is called a "package manager": each piece of software is contained in its own "package". If you need some new software, just open the package manager, choose the package and install it.

Forget about driversImagine you want to install Windows on a whole new, untouched, computer. For each little piece of hardware you'll have to find the latest driver (or use a CD), install it, and reboot from time to time. Video card, sound card, keyboard, mouse, motherboard chipset, etc. (better do the video card driver first or you're stuck with your high-end screen showing a very low resolution mode). And that comes after an already rather long installation of Windows itself.

Linux doesn't need separate drivers. All the drivers are already included in the Linux kernel, the core of the system, and that comes with every single Linux installation. This means:

A very fast and standalone installation process. Once you're done, you have everything you need to start working (including the software you'll be using,.

Out-of-the-box ready peripherals.

FILE SYSTEM HIERARCHY STANDARDThe Filesystem Hierarchy Standard (FHS) defines the main directories and their contents in Linux operating systems.

/ Primary hierarchy root and root directory of the entire file system hierarchy./boot Contains the boot loader. It contains everything required for the boot process/etc Contains all the configuration files like DNS, Proxy, Apache and other programs./home Contains the home directory of a normal user./root Contains the home directory of the super user, i.e., root./bin Contains commands that may be used by both the system administrator and by users./sbin Utilities used for system administration (root-only commands) are stored in /sbin, /usr/sbin, and /usr/local/sbin. /sbin contains binaries essential for booting, restoring, recovering, and/or repairing the system in addition to the binaries in /bin.

/lib The /lib directory contains those shared library images needed to boot the system and run the commands in the root filesystem, ie. by binaries in /bin and /sbin./usr Secondary hierarchy for read-only user data; contains the majority of multi-user utilities and applications./mnt or /media In Linux, all the removable devices like cdrom, pen drive, external hard disk, etc, are mounted /mnt or /media directory. Both are temporary mounting point and their work are same./var contains variable data files. This includes spool directories and files, administrative and logging data, and transient and temporary files./dev Directory is the location of device files. /tmp Temporary files./opt This directory is reserved for all the software and add-on packages that are not part of the default installation.

Linux has two interfaces: 1. Command Line Interface (CLI) 2. Graphical User Interface (GUI)It has 7 virtual consoles, by pressing Alt+Ctrl+f1 to Alt+Ctrl+f7, we can switch from one console to another.

Alt+Ctrl+f1 – 1st consoleAlt+Ctrl+f2 – 2nd consoleAlt+Ctrl+f3 – 3rd consoleAlt+Ctrl+f4 – 4th consoleAlt+Ctrl+f5 – 5th consoleAlt+Ctrl+f6 – 6th consoleAlt+Ctrl+f7 – 7th console

Command Line User Interface

Graphical User Interface

Accessing / or root drive graphically

Opening a Terminal

Root is by default an administrator name in Linux.

After login, when you open a terminal. You see the following prompt.

Here, root is admin name, localhost is the system name, tild(~) indicates the home directory (this implies, root is in his home directory) and # indicates authorized use, that means, root has the authority to access the particular directory. Incase of a normal user, it will show $ prompt.

BASIC COMMANDS AND GETTING HELP

whoami - print effective userid.date - print or set the system date and time.cal - displays a calendar.pwd - print name of current/working directory.ls –l - list directory contents with details.cd - Change the working directoryclear - Clear the screen

Getting help:-whatis (command) - searches a set of database files containing short

descriptions of system commands for keywords and displays the result on the standard output.

which (command) - Displays where a particular program in your path is located.

man (command) - manual pages from the Linux Documentation Project.

info (command) - read Info documents.command --help - for more help.

WORKING WITH FILES & DIRECTORIES

Creating a file

Copying a file

Moving a file

Removing a file

(To remove a file forcefully, add –f between command and file, then it wont ask you for the confirmation)

Renaming a file

In Linux everything is file. You should know how to edit a file. Later in the module you will understand how to edit a file using gedit and vi editor.

WORKING WITH DIRECTORIES

Creating a directory

Creating sub-directories

Creating multiple directories

Copying a directory

(To remove a directory forcefully, add –f between command and directory, then it wont ask you for the confirmation)

Moving a directory

Removing a directory

To remove an empty directory, type command

Renaming a directory

(To remove a directory forcefully, add –f between command and directory, then it wont ask you for the confirmation)

THANKS

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