Linux

Linux

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  Brief            History of Linux Brainbehind development Why Linux GNU Why GNU ? Where can you find Linux? Linux is Best!! Core components of Linux File system Drive letter’s Facts about Linux
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  History of UNIX/Linux Unix is a command line operating system developed around 1969 in the Bell Labs  Originally written using C  Unix is designed so that users can extend the functionality • To build new tools easily and efficiently • To customize the shell and user interface. • To string together a series of Unix commands to create new functionality. • To create custom commands that do exactly what we want.  Around 1990 Linus Torvalds of Helsinki University started off a freely available academic version of Unix  Linux is the Antidote to a Microsoft dominated future
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  Brain Behind Developmentof GNU LINUX Ken Thompson and Dennis Ritchie Linus Torvalds Richard Matthew Stallman Developer’s of Unix Developer of Linux Developer of GNU Project
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  Why Linux??       Multitasking : Severalprograms running at the same time. Multiuser : Several users on the same machine at the same time (and no two-user licenses!). Multiplatform : Runs on many different CPUs, not just Intel. Multiprocessor : SMP support is available on the Intel and SPARC platforms Memory Management : Has memory protection between processes, so that one program can't bring the whole system down Open Source : All source code is available, including the kernel and all drivers, the development tools and all user programs; also, all of it is freely distributable.
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  GNU(“GNU’s NOT UNIX”)      GNUis a Unix-like operating system that is free software—it respects your freedom. You can install versions of GNU (more precisely, GNU/Linux systems) which are entirely free software. What we provide. The GNU Project was launched in 1984 to develop the GNU system. The name ―GNU‖ is a recursive acronym for ―GNU's Not Unix!‖. ―GNU‖ is pronounced g'noo, as one syllable, like saying "grew" but replacing the r with n. A Unix-like operating system is a software collection of applications, libraries, and developer tools, plus a program to allocate resources and talk to the hardware, known as a kernel.
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  WHY GNU     The freedomto run the program, for any purpose The freedom to study how the program works, and adapt it to your needs Access to the source code is a precondition for this. The freedom to redistribute copies so you can help your neighbour. The freedom to improve the program, and release your improvements to the public, so that the whole community benefits Access to the source code is a precondition for this.
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  Where you findLinux ??      Mobile Linux Thanks to Google, Linux is a massive success on mobile phones, and is putting open source software into more hands than the desktop revolution ever has. Set-top boxes Set-top boxes are another Linux's success. These are the devices that sit next to your television, typically streaming content from a server, recording digital television or browsing the web. Routers and switches In the big brave world of the enterprise, networking and storage is what Linux does best, and some of this technology has filtered down to the home and small business market Audio engineering There are several high-profile synthesizers that are using Linux because of its stability, low latency and development ease. Desktops , Laptops, Gps , Navigation Systems and many more…..
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        Europe, 1.14% South America, 0.88% NorthAmerica, 0.72% Oceania, 0.72% Africa, 0.45% Asia, 0.34%
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  Linux is best Worksmore faster  Stable  No external Drivers  No illegal software's when you get it for free  Enjoy free and unlimited support  Forget about viruses  Multiple workspaces  No need of external antiviruses/antimalware/firewalls 
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  Flavour’s of Linux       LinuxDesktop Distribution  Ubuntu Linux Laptop Distribution  OpenSuse Linux Enterprise Desktop  SUSE Linux Enterprise Desktop (SLED Linux Enterprise Server  Red Hat Enterprise Linux (RHEL) and SUSE Linux Enterprise Server (SLES) Linux Security-Enhanced Distribution  Backtrack Linux Linux Multimedia Distribution  Ubuntu Studio
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  Core Components Of LinuxSystem
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  Boot loader      This isthe part of the system that is executed first. When you have only one operating system installed, it simply loads the kernel. If you happen to have multiple operating systems or multiple versions of the Linux kernel installed, it allows you to choose which one you want to start. The most popular boot loaders are GRUB (Grand Unified Boot loader) and LILO (Linux Loader). Most users don't need to care about the boot loader, because it is installed and configured automatically.
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  Kernel       The kernel isthe central component of the system that communicates directly with the hardware. In fact, the name "Linux" properly refers to a particular kind of this piece of software. It allows programs to ignore the differences between various computers. The kernel allocates system resources like memory, processor time, hard disk space and external devices to the programs running on the computer. It separates each program from the others, so that when one of them encounters an error, others are not affected. Most users don't need to worry about the kernel in day-to-day use, but certain software or hardware will require or perform better with certain kernel versions.
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  Shell      The shell isa textual interface that allows you to run programs and control the system by entering commands from the keyboard. Without a shell (or something that can replace it, like a desktop environment) it would be hard to make your system actually do something. The shell is just a program - there are several different shells for Linux, each of them offering different features. Most Linux systems use the Bourne Again Shell (Bash). Linux shells support multitasking (running several programs at once).
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  Initramfs      Initramfs, initial ramfile system is the successor of initrd. the initial file system that gets loaded into memory during the Linux start-up process. The Linux kernel mounts it as root file system and starts the init process from it. This will complete certain task before the real root file system is loaded. Initramfs needs to contain all of the device drivers and tools needed to mount the real root file system. The Initramfs is one solution to the chicken-and-egg problem of some mass storage devices and some file systems -- especially cryptographic file systems -requiring complex device drivers to read data from them, when device drivers are normally stored inside the file system in the mass storage device.
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  X Window Server      TheX window server is a graphical replacement of the command shell. It is responsible for drawing graphics and processing input from the keyboard, mouse, tablets and other devices. The X server is network transparent, that is, it allows you to work in a graphical environment both on your own computer as well as on a remote computer that you connect to across a network. The X server that is most used today is X.Org. Most graphical programs will only need the X server to run, so you can use them under any window manager and desktop environment.
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  DRIVE LETTER:     In general,the letters (fd, sd, hd) refer to the device type ('SATA, SCSI/SATA, IDE'), the third letter is for the device order (a the first, b the second, etc) and the numbers refer to the partitions the device has, starting by zero. hd refers to an IDE-type drive sd refers to a SCSI drive in general, but is mostly popular for SATA drives and CD/DVD fd is floppy disk  So for example:    the first (1) partition on your first (a) SATA drive is /dev/sda1 The third (3) partition on your second (b) SATA drive is /dev/sdb3 the second partition (2) of the second (b) IDE hard disk is '/dev/hdb2'
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  File System bin Linux commands var Configurationfiles Error logs External device files tmp media/ mnt Temporary fils dev usr Installed programs Device files Directories home etc
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  Security SELINUX: The United StatesNational Security Agency (NSA), the original primary developer of SELinux, released the first version to the open source development community under the GNU GPL on December 22, 2000 DAC(Discretionary Access Control): Briefly, Unix DAC allows the owner of an object (such as a file) to set the security policy for that object—which is why it's called adiscretionary scheme.
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  RED HAT 6.0  LAB Installation  Basic commands  Package installation  Yum installation
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  Facts You shouldknow !!!!       Linux is not an OS, but it is the kernel, GNU Linux is the OS and it comes in several hundred flavours. Major part of today’s Linux kernel is written in C programming language and assembly language and only 2% of today’s kernel contains code written by Torvalds. A Standard Linux Kernel of today has over 10 Million lines of code and it grows at the rate of 10% every year. About 4500 lines of codes are added and 1500 lines of code are changed everyday. Initially in 1991, Linux kernel version 0.01 was released with 10239 lines of code. 90% of the world’s most powerful supercomputers are using GNU/Linux. Top ten of supercomputers use Linux.] For those who think Linux can’t do Animation – Oscar-winning visual effects of theTitanic by James Cameron came from machines with Linux and Avatar was the last movie completely developed in 3D Applications on Linux platform using Foss Software. Exclaimed! As of January 2010, Linux still only has a 1.02% market share